Effects of dialysis and transplantation on red cell Na pump function in renal failure

Ion pumping by the erythrocyte Na, K-ATPase has been measured using ouabain-sensitive 86Rb flux in 11 non-dialysed patients with chronic renal failure (CRF), 13 patients on haemodialysis (HD), 13 patients on peritoneal dialysis (CAPD) and 15 patients with functional transplants (FT). Flux measurements were performed in plasma and simultaneous estimates of specific 3H-ouabain binding were made. The results indicate that, compared to normal controls, Na,K pump flux was reduced by 21% in CRF (p less than 0.01), 30% in HD (p less than 0.01), 15% in CAPD (p less than 0.02), and was normal in FT. Mean specific ouabain binding sites per cell (+/- SEM) were; controls 366 +/- 16; CRF, 290 +/- 16; HD, 344 +/- 17; CAPD, 321 +/- 18; FT, 345 +/- 26. Calculation of mean turnover rate per pump site indicated that patients on HD showed a 30% reduction compared to controls (influx 55 K ions/s versus 79 K ions/s, p less than 0.01). Cross-incubation experiments suggest that the lowered pump flux seen in the CRF and HD groups was due to plasma factors. This work shows that erythrocyte Na,K pump number is reduced in CRF, while patients on maintenance HD have normal pump numbers per erythrocyte but reduced pump turnover.     

Mechanisms of PKC-dependent Na+ K+ ATPase phosphorylation in the rat kidney with chronic renal failure

The present work was designed to study Na+ K+ ATPase alpha1-subunit phosphorylation in rats with chronic renal failure (CRF) in comparison with normal rats. Na+ K+ ATPase alpha1-subunit phosphorylation degree was measured by binding the McK-1 antibody to dephosphorylated Ser-23 in microdissected medullary thick ascending limb of Henle (mTAL) segments. In addition, the total Na+ K+ ATPase alpha1-subunit expression and activity were also measured in the outer renal medulla homogenates and membranes. CRF rats showed a higher Na+ K+ ATPase activity, as compared with control rats (18.95 +/- 2.4 vs. 11.21 +/- 1.5 micromol Pi/mg prot/h, p < 0.05), accompanied by a higher total Na+ K+ ATPase expression (0.54 +/- 0.04 vs. 0.27 +/- 0.02 normalized arbitrary units (NU), p < 0.05). When McK-1 antibody was used, a higher immunosignal in mTAL of CRF rats was observed, as compared with controls (6.3 +/- 0.35 vs. 4.1 +/- 0.33 NU, p < 0.05). The ratio Na+ K+ ATPase alpha1-subunit phosphorylation/total Na+ K+ ATPase alpha1-subunit expression per microg protein showed a non-significant difference between CRF and control rats in microdissected mTAL segments (2.11 +/- 0.12 vs. 2.26 +/- 0.18 NU, p = NS). The PKC inhibitor RO-318220 10(-6) M increased immunosignal (lower phosphorylation degree) in mTAL of CRF rats to 128.43 +/- 7.08% (p < 0.05) but did not alter McK1 binding in control rats. Both phorbol 12-myristate 13-acetate (PMA) 10(-6) M and dopamine 10(-6) M decreased immunosignal in CRF rats, corresponding to a higher Na+ K+ ATPase alpha1-subunit phosphorylation degree at Ser-23 (55.26 +/- 11.17% and 53.27 +/- 7.12% compared with basal, p < 0.05). In mTAL of CRF rats, the calcineurin inhibitor FK-506 10(-6) M did not modify phosphorylation degree at Ser-23 of Na+ K+ ATPase alpha1-subunit (100.21 +/- 3.00% compared with basal CRF). In control rats, FK 506 10(-6) M decreased the immunosignal, which corresponds to a higher Na+ K+ ATPase alpha1-subunit phosphorylation degree at Ser-23. The data suggest that the regulation of basal Na+ K+ ATPase alpha1-subunit phosphorylation degree at Ser-23 in mTAL segments of CRF rats was primarily dependent on PKC activation rather than calcineurin dependent mechanisms.     

The alteration of QT dispersion in hemodialysis subjects

OBJECTIVE: We attempted to observe the alterations in QTd and QTcd in chronic renal failure (CRF) patients before and after hemodialysis (HD) to determine the relevant determinants of QTc duration in HD. METHODS: The HD was carried out 2 or 3 times/week in a standard setting for 4-4.5 h. No drug therapy was applied during HD, except for isotonic NaCl infusions and sodium heparin. Maintenance drug therapy, including digitalis, antihypertensive, anti-anginal, and beta-blocking agents, was not changed. In the study, we investigated the alterations in QTd and QTcd in 68 CRF patients before and after HD with 12-lead ECG. Plasma Na(+), K(+), ionized Ca, creatinine, urea nitrogen, and hemoglobin were also controlled before and after HD. RESULTS: In our study QTd and QTcd significantly increased at the end of HD (p < 0.01). Plasma Na(+) and K(+) decreased, and ionized Ca increased after HD (p < 0.05, 0.01). Plasma Na(+), K(+), ionized Ca levels, ultrafiltration volume and myocardial ischemia appear to be the main determinants of QTc duration in HD, not hypertension, gender, patient age, or duration of chronic HD. CONCLUSION: Changes in plasma Na(+), K(+) and ionized Ca, the ultrafiltration volume and presence of ischemic heart disease in HD have significant effects on QTcd. ECG data demonstrate that the risk of arrhythmia could be higher with decreased plasma Na(+) and K(+), increased ionized Ca, the presence of ischemic heart disease and an increased ultrafiltration rate during HD. These results might provide some valuable references for proper HD programs.     

ICG pulse spectrophotometry for perioperative liver function in hepatectomy

BACKGROUND: The indocyanine green (ICG) clearance test has been used to estimate liver functional reserve before hepatectomy. However, changes in ICG clearance after hepatectomy have not been investigated, and their extent remains unknown. PATIENTS AND METHODS: The ICG(K) value, signifying the ICG elimination rate constant, was measured with pulse-dye densitometry before operation and 1, 2, 3, 5, and 7 days postoperatively in 22 patients who underwent liver resection of various extent. CT volumetry was used to calculate the residual liver volume ratio. The relationship between the pre- and postoperative ICG(K) value and the residual liver volume ratio was examined statistically. RESULTS: There was a significant drop in ICG(K) value, from 0.193 +/- 0.011 before operation to 0.160 +/- 0.013 on Postoperative Day 1, and then it remained significantly low at the postoperative examination times. The residual liver volume ratio was 70.2 +/- 5.4%. The estimated ICG(K) value, calculated by the preoperative ICG(K) value and the residual liver volume ratio, showed a significant correlation with the actual postoperative value (r = 0.859 on Postoperative Day 1, P < 0.0001). In five patients with prolonged jaundice, the estimated ICG(K) value was significantly lower than in those without it (0.077 +/- 0.028 versus 0.153 +/- 0.012, P = 0.0136). CONCLUSIONS: The perioperative ICG(K) value measured by pulse-dye densitometry revealed a significant decrease in ICG(K) after operation depending on the reduction in liver volume, and the estimated ICG(K) based on the residual liver volume was useful in predicting postoperative morbidity.     

Impedance cardiography: a potential monitor for hemodialysis

BACKGROUND: Impedance cardiography (ICG) technology has improved dramatically, and at least one device now can give a measurement of fluid status by using thoracic fluid content (TFC), along with cardiac output (CO) and cardiac index (CI). With a built-in sphygmomanometer cuff, it can also provide blood pressure (BP) and systemic vascular resistance index (SVRI). A currently available small portable ICG that provides reliable measures of fluid status could be an ideal noninvasive monitor for hemodialysis (HD), with the potential of helping avoid significant hemodynamic instability during HD. METHODS: A case series of patients with chronic renal failure was studied while undergoing HD using ICG (BioZ, CardioDynamics, Int. Corp., San Diego, CA). Parameters recorded at 15-min intervals included TFC, CI, BP (systolic, diastolic, and mean arterial), SVRI, and heart rate. Using the Pearson method, the percentage changes in each of the parameters during the HD session were correlated to the amount of fluid removed (FR), normalized to body weight. RESULTS: Forty-one patients were enrolled, but six patients were excluded due to incomplete data; therefore, 35 patients (13 men and 22 women) formed the basis of the analysis. The age range was 28 to 87 (mean 55.1 +/- 16.1) years. The amount of FR was 2.88 +/- 1.13 L (37.3 +/- 14.6 ml/kg). TFC decreased in all patients during the HD session (average reduction 12.7 +/- 8 kohms(-1)); whereas all other hemodynamic parameters showed both increases and decreases. The correlation of change in TFC with FR was moderate (r = 0.579, P = 0.0003); other hemodynamic parameters showed a poor correlation with FR. Neither the standard hemodynamic parameters nor the ICG device's special parameters were able to identify the five patients in this series who experienced significant hemodynamic instability or intradialytic hypotension. CONCLUSION: TFC, measured easily and noninvasively using ICG, correlates with the amount of fluid removed during HD. In comparison with the other hemodynamic parameters measured, TFC changed most consistently with fluid removal. Whether or not serial TFC measurements in a given patient at different HD sessions can guide the extent of FR will require additional study. This compact, easily operated, and nonobtrusive ICG device with the capability for continuously providing the standard hemodynamic parameters plus CO, TFC, and standard limb lead electrocardiography could replace current monitoring systems.     

Acute effects of hemodialysis on erythrocyte sodium fluxes in uremic patients

The acute effects of both acetate and bicarbonate hemodialysis on erythrocyte transmembrane sodium fluxes were investigated in 15 patients with chronic uremia. We observed a significance (p less than 0.01) stimulation of the Na+,K+ pump in both procedures, with a significant correlation to the amount of fluid removed during hemodialysis (r = 0.56, p less than 0.03). Outward Na+ cotransport fluxes significantly rose (p less than 0.05) after acetate hemodialysis and decreased (p less than 0.05) after bicarbonate hemodialysis. Minor and not significant pre- and posthemodialysis bidirectional changes were observed as regards the intraerythrocyte Na+ and K+ concentration, passive Na+ and K+ permeability, and Na+,Li+ countertransport. Hemodialysis may acutely affect the erythrocyte sodium pump and cotransport fluxes, possibly through the modulation of hormonal factors triggered by the extracellular volume changes.     

Hemodialysis and red cell cation transport in uremia: role of membrane free fatty acids

Active and facilitated cation transport in erythrocytes of uremic patients may be improved acutely by hemodialysis, although the mechanisms remain unknown. As nonesterified fatty acids (NEFA) can affect Na+ pump activity in vitro, changes in plasma and red cell membrane NEFA content following a single hemodialysis procedure were examined and compared with acute changes in erythrocyte cation flux rates in 34 hemodialysis patients. In nonsodium-loaded cells, small changes in Na+ pump flux with dialysis did correlate with changes in intracellular Na+ content (r = 0.59; N = 17; P less than 0.01). On average, neither maximal Na+ pump activity nor Na+/Li+ counter-transport flux improved with dialysis, but Na+/K+/Cl- cotransport rates rose 25% post-dialysis (P less than 0.02). Plasma NEFA levels rose 87% following hemodialysis but erythrocyte membrane NEFA content declined by 23% (P less than 0.001). Importantly, 24 of the 34 subjects studied had a decrease in erythrocyte membrane NEFA content of greater than 10%, and in these patients, the fall in membrane NEFA correlated with an increase in ouabain-sensitive Na+ efflux (r = 0.564; P less than 0.01). The effects of hemodialysis on both erythrocyte NEFA content and Na+ pump flux could be reproduced by incubating pre-dialysis cells in fatty acid-free albumin. We conclude that acute changes in membrane NEFA may modulate active cation transport in uremic erythrocytes.     

Variations in the disappearance rate of indocyanine green

Time-associated changes in the disappearance rate of indocyanine green from the blood (K.ICG) as an index of liver function, were studied. Blood was drawn 5 times at 3-minute intervals from 32 patients. Early, intermediate, and late K.ICG values were 0.087 +/- 0.040, 0.082 +/- 0.038, and 0.076 +/- 0.033 min-1, respectively, showing serial decreases. When blood was drawn 8 times at 2-minute intervals from 22 other patients, the means of the K.ICG values at 11 time points showed a nearly linear relationship (r = -0.986). These findings indicated that K.ICG is approximated by a linear function of time, K(t) = -K'.t + K0. According to this function, K.ICG is considered to decrease by 1.96% every minute. The K.ICG value determined by the conventional method is, therefore, a mean disappearance rate of 15 minutes, and K0 is considered to reflect the initial reaction speed.     

Regulation of the Na+/H+ antiporter in patients with mild chronic renal failure: effect of glucose.

BACKGROUND: The aim of this study was to determine the glucose-dependent regulation of the sodium-proton-antiporter (Na+/H+ antiporter) in patients with mild chronic renal failure (CRF). METHODS: We measured plasma glucose concentrations, plasma insulin concentrations, plasma C peptide concentrations, arterial blood pressure, cytosolic pH (pHi), cellular Na+/H+ antiporter activity, and cytosolic sodium concentration ([Na+]i) in 19 patients with CRF and 41 age-matched healthy control subjects (control) during a standardized oral glucose tolerance test. Intracellular pHi, [Na+]i, and Na+/H+ antiporter activity was measured in lymphocytes using fluorescent dye techniques. RESULTS: Under resting conditions, the pHi was significantly lower, whereas the Na+/H+ antiporter activity was significantly higher in CRF patients compared with controls (each P < 0.0001). The oral administration of 100 g glucose significantly increased the Na+/H+ antiporter activity in CRF patients from 13.35 +/- 1.26 x 10-3 pHi/second to 16.44 +/- 1.37 x 10-3 pHi/second after one hour and to 14.06 +/- 1.36 x 10-3 pHi/second after two hours (mean +/- SEM, P = 0.008 by Friedmans's two-way analysis of variance). In controls, the administration of 100 g glucose significantly increased the Na+/H+ antiporter activity from 4.23 +/- 0.20 x 10-3 pHi/second to 6.00 +/- 0.56 x 10-3 pHi/second after one hour and to 6.65 +/- 0.64 x 10-3 pHi/second after two hours (P = 0.0003). The glucose-induced enhancement of the Na+/H+ antiporter activity was more pronounced in CRF patients compared with controls (P = 0.011). Resting [Na+]i was not significantly different between the two groups. CONCLUSIONS: CRF patients show an intracellular acidosis leading to an increased Na+/H+ antiporter activity. In addition, high glucose levels exaggerate the differences in Na+/H+ antiporter activity already present between cells from patients with mild CRF and those from control subjects.     

Hyperhomocysteinemia in chronic renal failure patients: relation to tissue factor and platelet aggregation

BACKGROUND: A moderate increase in plasma total homocysteine (t-hcy) is considered to be an independent risk factor for cardiovascular disease (CVD) in general population. One of the mechanisms by which hyperhomocysteinemia contributes to cardiovascular risk has been explained to be the increased thrombotic potential. Elevated t-hcy levels were also reported in chronic renal failure patients because the renal function is a major determinant of serum t-hcy levels. PATIENTS AND METHODS: We measured serum hcy and ADP-induced platelet aggregation and plasma tissue factor as a major activator of the coagulation cascade in hemodialysis (HD), peritoneal dialysis (PD) and early stage chronic renal failure (early stage CRF) patients who are not receiving dialysis and compared with those of control. In addition, we also determined serum vitamin B12 and folat levels which are the important factors regulating the metabolism of t-hcy. RESULTS: Hcy levels in all patient groups were significantly higher (HD: 20.42 +/- 1.91 micromol/l, PD: 35.47 +/- 6.30, early stage CRF: 24.39 +/- 3.06) than the normal levels (10.74 +/- 0.74) in spite of standard multivitamin supplementation. The highest t-hcy values were found in peritoneal dialysis patients. Vitamin B12 levels in hemodialysis/peritoneal dialysis patients and folat levels in hemodialysis/early stage CRF patients were also significantly above those of control. On the other hand, the significant elevations in plasma tissue factor concentration were found in all patient groups (HD: 331.4 +/- 31.3 pg/ml, PD: 306.0 +/- 30.0, early stage CRF: 277.2 +/- 25.5 and Control: 69.5 +/- 13.5). t-hcy levels were positively correlated with creatinine (r: 0.791 p < 0.002) and tissue factor levels (r: 0.526 p < 0.05) in only early stage CRF group. The association between t-hcy and tissue factor persisted after these two parameters were adjusted for creatinine (r: 0.649 p < 0.05). On the other hand the same correlations were not observed in dialysis patient groups. In spite of the high tissue factor levels, ADP-induced platelet aggregations were found to be lower in all patient groups (HD: 102.6 +/- 6.7, PD: 98.6 +/- 7.6 and Early stage CRF: 84.9 +/- 7.6) than controls (154.9 +/- 13.7). CONCLUSION: These results suggest that hyperhomocysteinemia and increased tissue factor level are present in patients with renal failure, despite supplementation with vitamin B6 and B12 and folat. However, elevated levels of these thrombogenic factors are not linked with platelet aggregation.     

Increased levels of soluble TNF-alpha receptors and cellular adhesion molecules in patients undergoing bioincompatible hemodialysis

BACKGROUND: The study aimed to differentiate the effects of hemodialysis (HD) and chronic renal failure (CRF) on the levels of circulating tumor necrosis factor-alpha (TNF-alpha) and TNF-alpha receptors p55 and p75, soluble vascular cell adhesion molecule-1 (sVCAM-1), intercellular adhesion molecule-1 (sICAM-1), soluble endothelial-leukocyte adhesion molecule-1 (sE-selectin) and sP-selectin in 18 patients on regular HD treatment with cuprophane membrane in relation to 15 non-dialyzed CRF patients and 15 healthy controls. METHODS: The serum concentrations were determined with standard ELISA assays. RESULTS: Blood serum p75 and p55 were approximately tenfold increased in CRF (36.7 +/- 6.2 and 27.1 +/- 5.6 ng/ml) and HD patients (45.6 +/- 18.4 and 28.7 +/- 5.9 ng/ml) before the HD session (HD 0), during (HD 20) the session (45.7 +/- 18.4 and 28.5 +/- 7.3 ng/ml) and after (HD 240) the HD session (52.1 +/- 17.4 and 30.9 +/- 8.2 ng/ml) in comparison to control values (5.6 +/- 1.3 and 2.4 +/- 0.8 ng/ml, respectively) (p < 0.01). The highest increment of p75 at the end of HD session (HD 240) was also significantly higher than at preceding time points (HD 0 and 20) (p < 0.05). However, the remaining study parameters did not change during an HD session. Also, there were no relevant changes in TNF-alpha levels if (HD 0) 22.7 +/- 21.5 ng/ml and (HD 240) 21.1 +/- 18.9 ng/ml were compared. Chronic HD status was related to the increase of sVCAM-1 and sICAM-1 levels. Prior to HD, T0 sVCAM-1 and sICAM-1 concentrations were 2,180.4 +/- 761.8 and 567.3 +/- 218.8 ng/ml, during HD (T20): 2,172.7 +/- 759.2 and 602.3 +/- 379.9 ng/ml, and after HD (T240): 2,401.6 +/- 756.4 and 648.3 +/- 183.5 ng/ml, respectively (p < 0.05 vs. controls and CRF patients). sVCAM-1 and sICAM-1 serum levels (1,262.2 +/- 472.9 and 165.6 +/- 50.4 ng/ml) were similar in CRF patients and healthy controls (854.4 +/- 241.5 and 217.6 +/- 74.2 ng/ml, respectively). Even though serum sE- and sP-selectin in CRF patients did not differ from the control (39.8 +/- 21.3 vs. 42.1 +/- 18.9 ng/ml and 187.9 +/- 66.9 vs. 198.8 +/- 62.2 ng/ml, respectively), their levels were increased in HD patients up to 111.9 +/- 54.6 and 453.2 +/- 231.1 ng/ml in patients prior to HD, 118.7 +/- 66.2 and 350.8 +/- 114.8 ng/ml during the HD session and then 132.3 +/- 61.1 and 368.3 +/- 126.6 ng/ml, respectively, after its completion (p < 0.05 in comparison with CRF patients and controls). CONCLUSIONS: The increased circulating TNF-alpha receptors appear more associated with the uremic milieu than HD-related systemic inflammation, whereas increased soluble cellular adhesion molecules in patients undergoing bioincompatible HD may be related to the enhanced systemic inflammation specifically due to maintenance HD.     

Hepatic plasma flow during sodium nitroprusside-induced hypotension in humans

Changes in hepatic plasma flow (HPF) during sodium nitroprusside (SNP) induced hypotension were studied in 14 patients undergoing intracranial aneurysm surgery under neurolept anesthesia. Patients were monitored with the use of a radial artery catheter and a thermistor-tipped Swan-Ganz catheter. Hypotension was induced with incremental increases in the rate of SNP infusion until a stable mean arterial pressure (MAP) 35-55 mmHg had been achieved. In one group (Group A) of 10 patients, indocyanine green (ICG) clearance was determined simultaneously with hemodynamic variables, before and during SNP hypotension. In a second group (Group B) of four patients, a catheter was inserted into a hepatic vein to determine the ICG hepatic extraction (HE) coefficient. In Group A, MAP decreased from 73 +/- 10 (SD) to 41 +/- 9 mmHg, while cardiac index (CI) decreased in six patients and increased in four patients. However, the mean value of CI did not change significantly. The mean value of ICG clearance was not significantly affected by SNP hypotension. Nevertheless, a positive linear correlation existed between individual variation in CI and ICG clearance (r = 0.96). On the other hand, no correlation was noted between the change in MAP and ICG clearance. In Group B patients, the ICG HE coefficient remained unchanged during SNP hypotension, suggesting that ICG clearance varies only according to the variation in HPF. In conclusion, this study demonstrated that HPF did not decrease, despite a range of 20-60% decrease in blood pressure when CI is maintained during SNP hypotension.     

Albumin is the major plasma protein target of oxidant stress in uremia.

BACKGROUND: Patients with uremia are exposed to increased oxidative stress. Examination of the oxidation of individual plasma proteins may be useful in establishing specific pathways of oxidative stress in vivo and in determining functional consequences of oxidant stress exposure. We therefore examined oxidative modification of plasma proteins by carbonyl formation using Western blot immunoassay and enzyme-linked immunosorbent assay (ELISA) techniques in patients with chronic renal failure (CRF) and on chronic hemodialysis therapy (HD). METHODS: Plasma was obtained from 25 HD, 20 CRF, and 20 healthy volunteers, derivatized with 2,4 dinitrophenylhydrazine (DNP) and electrophoresed on duplicate 4 to 12% gradient sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) gels, transferred to nitrocellulose, and stained for DNP for carbonyls and amido black for protein content. Data are recorded as DNP area/protein area and are reported in densitometry units. Total plasma carbonyls were determined by ELISA. RESULTS: Plasma albumin is substantially more oxidized in HD than in healthy volunteers (1.22 +/- 0.14 densitometry units vs. 0.60 +/- 0.08, P = 0.002). There were no significant differences in oxidation of plasma transferrin, immunoglobulin, and fibrinogen in HD versus healthy volunteers. In CRF patients, plasma albumin is more oxidized compared with normal volunteers (1.36 +/- 0.20 densitometry units vs. 0.94 + 0.08, P = 0.09). There were no differences in oxidation of plasma transferrin, fibrinogen, and immunoglobulin in CRF patients versus healthy volunteers. An increased plasma protein carbonyl concentration in CRF patients compared with healthy volunteers was confirmed by ELISA (0.31 +/- 0.07 vs. 0.04 +/- 0.01 nmol/mg protein (P = 0.001). CONCLUSION: Albumin is the major plasma protein target of oxidant stress in CRF and HD patients.     

Improvement of leucocytic Na+ K+ pump activity in uremic patients on low protein diet.

Leucocytic Na+ K+ pump activity was assessed in 20 patients with advanced renal failure. Na+ K(+)-ATPase activity was reduced when compared with the values obtained from normal subjects (101.8 +/- 48.6 versus 165.13 +/- 8.9 microM of Pi hr-1.g-1; P less than 0.001) and the mean 86Rb uptake by U 937 cells was depressed by 38% after the addition of patients' sera. Subsequently, patients were put on a diet providing 0.3 g protein/kg body weight daily and supplemented with ketoacids. After three months of dietary treatment Na+ K(+)-ATPase activity increased to 142 +/- 48.3 (P less than 0.01) and reached normal values at the sixth month (162.8 +/- 54.70 microM of Pi hr-1.g-1; P less than 0.001) whereas 86Rb uptake increased by 23 percent when compared to initial values. These data suggest that among the different mechanisms which have been advanced to explain the defects in the Na+ pump observed in uremic patients, circulating inhibitors deriving from alimentary protein intake may affect cation transport.     

Longitudinal study of apoptosis in chronic uremic patients

Uremia is associated with a state of immune dysfunction, increasing infection and malignancy rates. Dysregulation of homeostasis may be directly related to abnormal apoptosis regulation, a process which is crucial for the maintenance of the biologic system. Abnormal apoptosis rates (ARs) have been reported in the literature. We performed a longitudinal study over a 10-week period in three groups of uremic subjects-hemodialysis (HD), peritoneal dialysis (PD), and predialysis chronic renal failure (CRF). Our results showed that ARs were consistent over the observed period. Monocytes extracted from HD and CRF subjects had higher ARs compared to PD and controls (HD: 26.06 +/- 8.82; CRF: 26.96 +/- 12.81; PD: 14.77 +/- 5.87; C: 11.42 +/- 4.60) when placed in culture medium. The plasma of HD and CRF subjects when incubated with U937 cells had a stronger apoptogenic potential compared with PD and controls (HD: 26.08 +/- 11.39; CRF: 24.87 +/- 9.07; PD: 12.13 +/- 4.51; C: 11.69 +/- 4.02). Inflammatory markers (C-reactive protein [CRP], procalcitonin) and cytokines (interleukin [IL]-1beta, IL-2, IL-10) had a generally poor correlation except for tumor necrosis factor (TNF)-alpha (p < 0.001). The phagocytic ability of U937 cells when incubated with the various plasma demonstrated impaired response in the HD and CRF subjects (HD: 27.56 +/- 6.67; CRF: 30.24 +/- 9.08; PD: 36.55 +/- 9.80; C: 40.04 +/- 6.98). These results suggest continuous renal purification, such as in continuous ambulatory peritoneal dialysis (CAPD), may have advantages over intermittent therapies in regulating apoptosis and maintaining biologic function and homeostasis.     

Spinal cord sodium, potassium, calcium, and water concentration changes in rats after graded contusion injury

Spinal cord Na, K, Ca, and H2O changes were measured 6 h after graded contusion injuries in 40 Sprague-Dawley rats. A 10 g weight was dropped 1.25 cm (n = 6), 2.5 cm (n = 7), 5.0 cm (n = 6), or 7.5 cm (n = 7) onto the thoracic spinal cord of 26 rats. An additional 10 rats served as laminectomy controls and 4 rats were unoperated controls. At 6 h after surgery or injury, the spinal cords were rapidly cut into 4 mm segments, weighed to obtain tissue wet weights (W), dried for 14-16 h at 97 degrees C in a vacuum oven (30 mmHg), and reweighed for tissue dry weights (D). Water concentrations ([H2O]d) were estimated from (W-D)/D in units of ml/g D. Ionic concentrations ([Na]d, [K]d, and [Ca]d) of the tissue samples were measured by atomic absorption spectroscopy with units of mumol/g D. Ionic shifts (delta [Na]d, delta [K]d, delta [Ca]d) were calculated by subtracting laminectomy control values from those measured in injured cords. Laminectomy alone significantly increased [Na]d and [H2O]d compared to unoperated controls. Mean +/- standard deviations of [H2O]d, [Na]d, [K]d, and [Ca]d were, respectively, 1.95 +/- 0.07, 182.6 +/- 5.9, 277.2 +/- 11.8, and 12.1 +/- 1.4 in unoperated controls; 2.12 +/- 0.08, 238.6 +/- 9.2, 277.8 +/- 9.2, and 11.7 +/- 1.1 in laminectomy controls. At the impact site, [K]d fell by 14-37% and [H2O]d rose by 14-24%, [Na]d by 13-64%, and [Ca]d by 65-137% of laminectomy control values. delta [Na]d, delta [K]d, and delta [Ca]d correlated linearly with impact velocities; [Ca]d increased by 1.0% per cm/sec (r = 0.995, p less than 0.005), [Na]d increased 0.67% per cm/sec (r = 0.950, p less than 0.01), and [K]d decreased 0.34% per cm/sec (r = 0.964, p less than 0.01). Neither delta [H2O] nor delta [Na]d + delta [K]d consistently predicted impact velocity. [Na]d + [K]d correlated with [H2O]d with a slope of 177.4 mumol/ml (r = 0.697, p less than 0.005). Since Na and K constitute greater than 95% of tissue inorganic ions, the slope approximates net ionic shift per ml of water entry or the ionic osmolarity of edema fluid. These results indicate that increasing contusions produce graded ionic shifts and that edema does not predict contusion severity. These data support our hypothesis that net ionic shifts cause edema in injured spinal cords.     

Effects of pneumonectomy on pulmonary input impedance

The long-term effects of pneumonectomy on the pulmonary circulation quantifiable through pulmonary input impedance analysis were studied. Excision of the left lung was performed in purebred beagle dogs aged 6 to 10 weeks (n = 6 group I) or 1 year (n = 8 group II). Unoperated beagles served as controls (n = 8 group III). When the dogs were 5 years of age, pulmonary pressure and flow were measured and the impedance spectra calculated. Characteristic impedance (Zo) (indicative of changes in proximal vessel physical properties) and pulmonary vascular resistance (PVR) (indicative of the distal response) were estimated. In group III the cardiac output (CO) was 1.7 +/- 0.4 L/min, mean pressure 16 +/- 5 mm Hg, PVR 605 +/- 448 dyne-sec/cm, and Zo 204 +/- 76 dyne-sec/cm. Group I results exhibited bimodal distributions that were not statistically different from results of groups II or III; four dogs had spectra comparable to those of group III, while two dogs had developed moderate hypertension and high PVR and Zo. Group II results were more normally distributed, and comparison with group III indicated statistically significant differences (P less than 0.05) in CO (1.1 +/- 2 L/min), PVR (1396 +/- 573 dynes-sec/cm), and Zo (543 +/- 273 dynes-sec/cm). Doubling of PVR and Zo in group II indicated that proximal vessel compliance and peripheral perfusion radius had not increased following pneumonectomy in adult beagles. Group I results indicate that marked facilitory adaptation can occur when pneumonectomy is performed in puppies; however, the adaptation may not be based on true lung growth and, therefore, may not be sustained indefinitely.     

Influence of haemodialysis and left ventricular failure on peripheral A(2A) adenosine receptor expression.

BACKGROUND: Haemodialysis (HD) sometimes accelerates left ventricular failure (LVF). As adenosine (ADO) is strongly implicated in cardiovascular functions, particularly via A(2A) receptor activation and as changes of peripheral A(2A) receptors mirror changes occurring in the cardiovascular system, we examined the influence of HD and LVF on both ADO plasma concentration and the expression of A(2A) receptors (i.e. Bmax, K(D) and mRNA amount) of peripheral blood mononuclear cells. METHODS: This cross-sectional study included 61 chronic renal failure (CRF) patients: 41 without LVF (24 haemodialysed and 17 undialysed) and 20 with LVF (9 haemodialysed and 11 undialysed). Ten LVF patients without CRF and 10 healthy subjects were also examined. RESULTS: (i) Bmax values of CRF patients without LVF were significantly decreased in undialysed patients compared with haemodialysed patients, and compared with controls (69 +/- 25 vs 98 +/- 33 vs 180 +/- 60 fmol/mg of protein, P < 0.05). Bmax values of CRF patients with LVF were lower in undialysed patients than in haemodialysed patients (60 +/- 27 vs 101 +/- 27 fmol/mg of protein, P < 0.05). Bmax values of LVF patients without CRF were lower than in controls (51 +/- 19 vs 180 +/- 60 fmol/mg of protein). (ii) A(2A) mRNA expression was increased in haemodialysed patients compared with controls (20.2 +/- 0.75 vs 17.6 +/- 1.3, P < 0.05). (iii) ADO plasma levels were high in haemodialysed patients and further increased during the HD sessions. CONCLUSION: The number of A(2A) receptors was decreased by CRF with or without LVF. However, this decrease was less important in haemodialysed patients. The changes in peripheral A(2A) receptor expression suggest a significant inflammatory response to HD and heart or kidney failure. Whether these changes do reflect alterations in cardiomyocytes needs further investigation.     

Skeletal muscle water and electrolytes in chronic renal failure. Effects of long-term regular dialysis treatment

Skeletal muscle water, Cl, Na and K were studied in 24 patients with predialysis chronic renal failure (CRF) and in 16 patients under regular dialysis treatment (RDT) for 8-16 years; 35 healthy controls were also examined. Total Cl, Na and water (Clm, Nam, TW) were high in both CRF and RDT groups (p less than 0.001); high TW in CRF was due to both extra (ECW) and intracellular (ICW) fractions, which were calculated from Cl space; in RDT only ECW was increased and ICW was normal. Muscle K was diminished in CRF, in reference to both muscle fat free dry solids and ICW, and it was slightly but significantly higher than normal in RDT. The findings demonstrate that high cell volume and low intracellular K observed in CRF are fully corrected by long-term hemodialysis, probably because these abnormalities are mainly related to cell function disturbances due to uremic state. On the contrary, the persistence of high total Cl, Na and muscle ECW seems to be an expression of expanded extracellular fluid volume.     

Modulation of pulmonary NA+ pump gene expression during cold storage and reperfusion

BACKGROUND: Reperfusion injury with pulmonary edema continues to be a major complication after lung transplantation. Alveolar fluid homeostasis is regulated by Na+/K+-ATPase activity on the basolateral surface of alveolar epithelial cells. Intact Na+/K+-ATPase is essential to the resolution of pulmonary edema. We characterized the effects of cold ischemia and reperfusion on expression of Na+/K+-ATPase mRNA and protein. METHODS: Baseline values for Na+/K+-ATPase mRNA and protein were determined from freshly harvested lungs with no cold storage time or reperfusion (group I). Group II lungs were analyzed after cold storage times of 12 or 24 hr without subsequent reperfusion. Group III lungs were analyzed after cold storage times of 12 or 24 hr with subsequent reperfusion. Lungs were flushed with either Euro-Collins (EC) or University of Wisconsin (UW) solution in each group. All samples were quantified for Na+/K+-ATPase mRNA and Na+/K+-ATPase protein. Physiological parameters including oxygenation and compliance were also measured. RESULTS: There were no significant differences in the level of mRNA and protein for samples that were cold stored without reperfusion (group II). With reperfusion (group III) there was a significant increase in the level of the Na+/K+-ATPase mRNA after 12 hr of storage for both EC and UW. After 24 hr of storage and subsequent reperfusion, lungs flushed with EC had significantly decreased Na+/K+-ATPase protein and mRNA, although lungs preserved with UW maintained their increased levels of Na+/K+-ATPase protein and mRNA. CONCLUSIONS: Our data suggest that ischemia-reperfusion injury results in an initial up-regulation of Na+/K+-ATPase mRNA. With prolonged injury in lungs preserved with EC, the level of the mRNA decreased with a corresponding decrease in the Na+/K+-ATPase protein. The different response seen in EC versus UW may be explained by better preservation of pump function with UW than EC and correlates with improved physiological function in lungs preserved with UW solution.