Intraperitoneal atrial natriuretic peptide increases peritoneal fluid and solute removal

BACKGROUND: Atrial natriuretic peptide (ANP) is a hormone with well-known diuretic and vasodilating properties. Recently it was reported that ANP could increase the peritoneal fluid formation and increase peritoneal solute clearance. This study investigated the effect of ANP on peritoneal fluid and solute transport characteristics. METHODS: Eighteen male Sprague-Dawley rats were divided into three groups. A four-hour dwell study using 25 mL 2.27% glucose dialysis solution with 50 microg/kg ANP (N = 6, H-ANP) or 5 microg/kg ANP (N = 6, L-ANP) or without ANP (N = 8, control) and frequent dialysate and blood sampling was done in each rat. Radiolabeled human albumin (RISA) was added to the solution as an intraperitoneal volume marker. RESULTS: The intraperitoneal volume was significantly higher in the H-ANP group as compared with the control group and the L-ANP group. The drainage volume was 26.2 +/- 1.1, 25.5 +/- 0.7, and 29.8 +/- 0.8 mL for the control, L-ANP, and H-ANP groups, respectively (P < 0.01). This was related to significant differences in the peritoneal fluid absorption rates (K(E); estimated as the RISA elimination coefficient): 39 +/- 3, 38 +/- 3, and 19 +/- 4 microL/min, and in the direct lymphatic absorption rate (K(EB); estimated as the clearance of RISA from dialysate to blood): 7 +/- 1, 6 +/- 1, and 4 +/- 1 microL/min for the control, L-ANP, and H-ANP groups, respectively (all P < 0.01). No differences were found in the intraperitoneal volume, K(E), and K(EB) between the control group and the L-ANP group. The diffusive mass transport coefficient (K(BD)) for urea, sodium, potassium, and total protein did not differ among the three groups. However, the glucose D/D(0) was significantly higher, and the K(BD) for glucose was significantly lower in the H-ANP group as compared with the other two groups. Solute clearances (+175% for sodium and +26% for potassium) were significantly increased in the H-ANP group, mainly as a result of the increased fluid removal in this group. CONCLUSIONS: Our results suggest that ANP may decrease peritoneal fluid absorption (by 51%, partially because of decreasing the direct lymphatic absorption), resulting in a significant increase in peritoneal fluid removal and small solute clearances. While the basic diffusive permeability of the peritoneal membrane was not changed, the peritoneal glucose absorption was retarded by adding ANP to peritoneal dialysate, perhaps through interaction of ANP with glucose metabolism.     

Plasma calcitonin gene-related peptide and atrial natriuretic peptide levels during resection of pheochromocytoma.

Calcitonin gene-related peptide (CGRP) and atrial natriuretic peptide (ANP) are potent hypotensive agents. To determine if they play a counterregulatory role in catecholamine excess in patients with pheochromocytoma, plasma levels were measured in four patients undergoing resection of sporadically occurring tumors. Each patient was prepared with phenoxybenzamine hydrochloride (Dibenzyline); two patients also received propranolol. Blood was obtained for plasma levels of epinephrine, norepinephrine, CGRP, and ANP at induction of anesthesia, skin incision, tumor manipulation, tumor removal, and 24 hours after operation. Baseline plasma norepinephrine and epinephrine levels were markedly elevated and increased significantly with tumor manipulation and decreased significantly 24 hours after operation. CGRP and ANP levels were slightly elevated throughout but did not change significantly with tumor manipulation or early after tumor resection. Circulating CGRP and ANP do not appear to have an acute counterregulatory role in catecholamine excess in patients with pheochromocytoma but may exert some influence on postoperative hypotension after tumor removal.     

Cardiac function and cardiovascular hormone balance during hemodialysis with special reference to atrial natriuretic peptide

Echocardiographically determined left ventricular function and cardiovascular hormone balance were assessed before and after hemodialysis in 10 patients who had been on hemodialysis for 4 months to 15 years. Plasma levels of atrial natriuretic peptide (ANP), antidiuretic hormone (ADH), renin activity and aldosterone were determined. All patients had vector- and echocardiographic evidences of slight to moderate left ventricular hypertrophy. The body weight decreased 2.0 kg (3.3 +/- 0.5%) with dialysis. Nine out of ten patients showed a slightly reduced ejection fraction that normalized after dialysis (p less than 0.05). Left atrial and ventricular systolic dimensions were around the upper reference limit before dialysis with a decrease after dialysis (p less than 0.05 and p less than 0.02, respectively). The levels of ANP decreased with dialysis from 2-17 times to 1 to 15 times the upper reference value in nine out of the ten patients. In the whole group the decrease was 117 +/- 35% (p less than 0.005). A significant regression was obtained between percentage decrease of body weight and percentage change of ANP (r = 0.67; p less than 0.05). The plasma concentration of ADH did not change following dialysis but the mean value was significantly higher than the mean value of the reference group of the laboratory (p less than 0.05 before and p less than 0.005 after dialysis). Renin activity and aldosterone levels were low and did not change during dialysis. In conclusion, the slight left ventricular hypertrophy may partly be a response to volume overload with hyperdynamic circulation and partly to metabolically depressed myocardial function.(ABSTRACT TRUNCATED AT 250 WORDS)     

Central blood volume, atrial natriuretic peptide and intermittent hemodialysis

OBJECTIVE: Hypotension and decreased serum atrial natriuretic peptide (ANP) in response to hemodialysis have both been attributed to a decrease in central blood volume. The aim of this study was to test whether circulatory performance and serum ANP were related to changes in central blood volume, in conjunction with hemodialysis with loss of plasma volume. MATERIAL AND METHODS: Ten uremic patients without cardiopulmonary symptoms were investigated before, immediately after and 2 h after a regular dialysis session. Bolus indocyanine green dilution was used for the measurements of central blood volume, cardiac output and stroke volume. Serum ANP was analyzed using a radioimmunoassay technique. RESULTS: Hemodialysis resulted in a 3.8 +/- 1.3 kg decrease in weight and an increase in hemoglobin concentration, while central blood volume, stroke volume, cardiac output, blood pressure and serum ANP fell in parallel. Two h after dialysis, central blood volume recovered to its pre-dialytic level, whereas weight, plasma volume, stroke volume, blood pressure and serum ANP stayed at low levels. There were strong correlations between serum ANP and hemoglobin concentration, stroke volume, cardiac output and blood pressure, but not between serum ANP and central blood volume. Correlations between central blood volume and plasma volume, stroke volume, cardiac output, and blood pressure were also weak. CONCLUSIONS: The close correlation between circulatory performance and serum ANP implies a reduction in preload in response to dialysis. The lack of correlations between central blood volume and circulatory performance and serum ANP suggests that the compliance in the central vasculature is increased in response to dialysis.     

Plasma levels of atrial natriuretic peptide in severe burn injury

Atrial natriuretic peptide (ANP) plays a part in the regulation of volume homeostasis and possibly, in the pathophysiology of water and electrolyte disorder. Patients with serious burn injuries risk huge body fluids losses, which are compensated for by perfusion. Blood volume and the renin and aldosterone system are also disturbed. This study measured plasma ANP and vasoactive intestinal polypeptide (VIP) in patients with >20% total burned surface area (TBSA), at admission and 24 h post-admission.Eleven patients (mean age 46.5 years, 8 males) with a mean TBSA of 34.5% were sampled. Standard treatment was given. Eleven closely age-matched volunteers were used as controls. A specific ELISA method suitable for the measurement of ANP and VIP was used.ANP was higher (p<0.0001), while VIP was lower (p=NS) in patients' samples compared to controls. While the level of VIP was higher at 24 h post-admission, mean ANP level remained about the same. The increased levels of plasma ANP may result from volaemic disturbances during resuscitation, low VIP levels, the increase in pulmonary resistance or post-burn stress.     

Plasma atrial natriuretic peptide and natriuretic response to water immersion in patients with nephrotic syndrome.

Eight nonnatriuretic (daily Na excretion less than 50 mEq), 4 natriuretic (daily Na excretion greater than 50 mEq), and 4 steroid-responsive nephrotic patients, and 12 normal controls were studied with a 4-hour water immersion with measurements of electrolytes, plasma atrial natriuretic peptide (ANP), plasma renin activity (PRA), and plasma aldosterone (PA) [corrected]. Four nonnatriuretic patients further received 25 g albumin infusion, with a subsequent 2-hour water immersion study. The results are as follows: (1) In the nonnatriuretic patients, the extremely low basal Na excretion rate, high PRA, and PA levels indicated a state of active Na retention. In spite of the water-immersion induced suppression of PRA and PA and a comparable magnitude of plasma ANP increment, the natriuretic response to water immersion was blunted in the nonnatriuretic patients. (2) In the natriuretic patients, water immersion resulted in a similar magnitude of natriuresis but a higher degree of plasma ANP increment in comparison to the normal controls. (3) Natriuretic and plasma ANP responses to water immersion were not different between the steroid-responsive patients and normal controls. (4) The increase in plasma ANP and the suppression of PRA and PA after 25 g albumin infusion did not result in natriuresis until the further suppression of PRA and PA and the further stimulation of plasma ANP by subsequent water immersion. The above results indicate that the natriuretic and plasma ANP responses to water immersion are related to the basal Na status in nephrotic patients.(ABSTRACT TRUNCATED AT 250 WORDS)     

Plasma atrial natriuretic peptide and endothelin levels in acute poststreptococcal glomerulonephritis

Plasma levels of atrial natriuretic peptide (ANP) and of endothelin (ET) were significantly elevated (87.7±13.9 pg/ml and 79.7±10.8pg/ml, respectively) during the acute phase of acute poststreptococcal glomerulonephritis (APSGN). Plasma renin levels were normal, fractional excretion of sodium (FE_Na) was 0.5±0.1% and creatinine clearance (C _Cr) averaged 82.2±18.3 ml/min per 1.73 m². In the recovery phase of the disease (n=12), levels of ANP (23.6±6.7 pg/ml) and ET (43.1±2.4 pg/ml) fell and were not significantly different from those measured in 11 control subjects. FE_Na increased to 1.3±0.1% andC _Cr to 113.5±12.1 ml/min per 1.73 m² (all values mean ± standard error). ANP did not correlate with PRA, blood pressure,C _Cr or FE_Na. There was an inverse relationship between the ET level and FE_Na in the acute phase of the disease (r=0.489,P<0.05), but no significant correlation between ET and blood pressure, PRA,C _Cr or ANP was found. We suggest that, despite the sodium retention, the increased ANP level in APSGN indicates unresponsiveness of the kidneys to ANP; the increased ET levels may contribute to this.     

Plasma atrial natriuretic peptide concentration and renin activity during overhydration with 1.5% glycine solution in conscious sheep

We estimated the changes of fluid compartment volumes and concomitant effects on plasma atrial natriuretic peptide (ANP) and plasma renin activity (PRA) for up to 4 hr after intravenous infusion of 57 ml/kg of 1.5% glycine solution over 40 min in six conscious ewes. Infusions of the same volumes of isotonic saline served as controls. Glycine infusions resulted in a four-fold increase and saline in a doubling of the plasma ANP concentration, despite a more pronounced volume expansion from saline. The ANP level remained significantly elevated for 2 hr after glycine infusion. This result suggests that glycine has a specific ANP-stimulating effect which may contribute to the hypovolemia, hypotension, and natriuresis seen in the “transurethral resection (TUR) syndrome”. The PRA decreased by about 50% in response to both infusions. However, PRA returned to the baseline level at the end of the glycine infusion, whereas it remained depressed during the entire follow-up period after saline infusion. This is in accordance with a pure volumetric influence on renin release, since calculations of fluid distribution between different compartments suggested that, in contrast to the effect of saline, only a small amount of irrigant water remained in the extracellular fluid after glycine administration. The urea and creatinine clearances increased only in response to isotonic saline. Glycine infusion was even followed by reduction of the creatinine clearance. © 1994 Wiley-Liss, Inc.     

Plasma alpha-human atrial natriuretic peptide and volume status in chronic haemodialysis patients

The relationship between inferior vena cava diameter (VCD), collapse-index (CI) determined by echography, and alpha-human atrial natriuretic peptide (alpha-h-ANP) concentrations were studied in 19 chronic haemodialysis patients. A significant correlation was found between VCD and alpha-h-ANP before dialysis (r = 0.78; P less than 0.0001). No such correlation was found between CI, left atrial diameter and left ventricular end-diastolic diameter, and alpha-h-ANP values. In nine patients who according to vena cava indices were hypervolaemic before dialysis (group I), alpha-h-ANP concentrations were significantly greater than in ten normo- or hypovolaemic patients (group II): 392.8 +/- 134.1 pg/ml and 168.0 +/- 62.5 pg/ml respectively. Although the same amount of fluid was ultrafiltrated in both groups, alpha-h-ANP decreased significantly in group I only, whereas in group II the decrease was not significant: 392.8 +/- 134.1 to 185.2 +/- 81.7 (P less than 0.001); 168.0 +/- 62.5 to 130.0 +/- 59 respectively. After achieving normovolaemia alpha-h-ANP concentrations in patients with a mitral valve insufficiency grade I was doubled compared to normovolaemic patients without mitral valve insufficiency, suggesting that alpha-h-ANP release will also occur from the left atrium. In the latter group alpha-h-ANP values were approximately doubled compared to healthy controls. The highly significant correlation between VCD before dialysis and changes in alpha-h-ANP during dialysis with fluid removal underlines the value of vena cava diameter in estimating volume status.     

Biological activity of endogenous atrial natriuretic peptide during cardiopulmonary bypass

To evaluate the effect of cardiopulmonary bypass (CPB) on atrial natriuretic peptide (ANP) biological activity in patients undergoing cardiac operations, we conducted a prospective study. Ten patients undergoing mitral valve surgery were enrolled. Plasma levels of ANP and cyclic guanosine monophosphate (cGMP), hemodynamic variables, and renal function parameters were assessed perioperatively. The molar ratio of cGMP to ANP (as a marker for ANP biological activity) decreased significantly (p < 0.05) during CPB despite similar plasma ANP levels. The ratio correlated inversely with the duration of CPB (r = -0.85, p = 0.002). The ratio also correlated with fractional sodium excretion (r = 0.65, p = 0.04) and correlated inversely with pulmonary vascular resistance (r = -0.79, p = 0.009) and atrial filling pressure (r = -0.84, p= 0.003) postoperatively. CPB decreased the molar ratio of cGMP to ANP, which may represent ANP biological activity, such as vasodilation and natriuresis. The phenomenon may contribute to water-sodium retention and pulmonary hypertension after cardiac surgery.     

Plasma atrial natriuretic factor (alpha ANF) during hemodialysis (HD) and hemofiltration (HF).

Plasma concentrations of immunoreactive alpha ANF were measured before, during, and after 3 hours of hemodialysis (HD) and hemofiltration (HF). In seven healthy subjects plasma alpha ANF concentrations were measured to serve as controls. Highly elevated pre-treatment alpha ANF levels were obtained in the HD group (286 +/- 52 pg/ml, mean +/- SE), and in the HF group (275 +/- 48 pg/ml) as compared with the controls (40 +/- 3 pg/ml). The effect of both HD and HF on the alpha ANF concentration was not significant after the first hour of treatment. However, a significant decrease was obtained after the second (HD = 244 +/- 49, HF = 140 +/- 17) and third hours (HD = 244 +/- 48, HF = 135 +/- 15) (p less than 0.05) in both treatments. A steeper decline in the alpha ANF concentration was notable during HF compared with HD. There was a significant difference (p less than 0.05) when both modalities were compared at the end of treatment. A correlation (r2 = 0.98, p less than 0.001) was noted between changes in the alpha ANF levels and the ultrafiltration (UF) volumes only during HF. Plasma alpha ANF concentrations at the filter outlet were lower than at the inlet in both groups. It is concluded that the plasma alpha ANF concentrations are highly elevated in chronic renal failure patients. Despite the decrease in these concentrations during HD and HF it did not reach the normal plasma level. Monitoring of plasma alpha ANF may be a useful indicator for the extracellular volume status during HD and HF treatments.     

Cardiovascular effects of human atrial natriuretic peptide during renal transplantation

BACKGROUND: We evaluated the cardiovascular effects of human atrial natriuretic peptide (hANP) in the recipients of renal transplantation. METHODS: Anesthesia was maintained by inhalation of nitrous-oxide and isoflurane in oxygen, with epidural block. The recipients were divided into three groups; one group received no hANP infusion as control and the other groups received continuous infusion of hANP at the rate of either 0.05 microg x kg(-1) x min(-1) or 0.1 microg x kg(-1) x min(-1). Intravenous infusion of hANP was started at the anastomosis of renal artery after the fresh frozen plasma was loaded to achieve PCWP over 17 mmHg. In each group, we examined cardiovascular changes by using a pulmonary artery catheter and transesophageal echocardiography. The measurements were done before and after 15 minutes of hANP infusion. RESULTS: In comparison with control, the decreases in PCWP and CVP were significant in the 0.1 microg x kg(-1) x min(-1) group. An increase in CI and the reduction of CVP were significant in 0.05 microg x kg(-1) x min(-1) group, when compared with control group. In the 0.1 microg x kg(-1) x min(-1) group, the reductions of PCWP and CVP and MAP were significant, but the significant increase in CI was characteristic in the 0.05 microg x kg(-1) x min(-1) group. CONCLUSIONS: We conclude that the low-dose infusion of hANP in the recipients of renal transplantation is useful for the optimal anesthetic care because of the cardiovascular improvement.     

Plasma concentration and renal effect of human atrial natriuretic peptide in nephrotic syndrome

To elucidate the pathophysiological role of atrial natriuretic peptide (ANP) in nephrotic syndrome, the plasma level of ANP and renal response to exogenous human alpha-ANP (alpha-hANP) were measured in untreated adult patients with idiopathic nephrotic syndrome (NS) and compared with those of normal volunteers (NL). The plasma concentration of immunoreactive ANP (ir-ANP) in NS (112 +/- 9.8 pg/ml, n = 9, mean +/- SE) was not significantly different from that in NL (98 +/- 8.0 pg/ml, n = 13). However, a significant positive correlation was observed between the plasma ir-ANP level and blood volume in NS (r = 0.714, p less than 0.05). In an infusion study with synthetic alpha-hANP (25 to 100 ng/kg/min), the urine flow rate increased from 0.67 +/- 0.08 to 7.11 +/- 1.08 ml/min in NL (n = 5, p less than 0.01) and from 0.64 +/- 0.16 to 2.88 +/- 0.70 ml/min in NS (n = 9, p less than 0.05) and the urinary sodium excretion increased from 115 +/- 16 to 466 +/- 62 microEq/min in NL (p less than 0.01) and from 51 +/- 8 to 207 +/- 58 microEq/min in NS (p less than 0.01). The absolute and percent changes in urine flow rate and the absolute change in sodium excretion were lower in NS (p less than 0.05) than in NL. The percent change in sodium excretion in NS did not differ from that in NL. In 2 patients with high plasma ir-ANP concentrations, however, infusion of ANP induced poor sodium excretion (59 and 95 microEq/min at 100 ng/kg/min ANP infusion, respectively). Hemodynamic and renal parameters such as blood pressure, pulse rate and creatinine clearance were similarly affected in both NL and NS. We also found that the urinary excretion of protein was significantly increased in NS (p less than 0.05) during infusion of alpha-hANP. Our data suggest that the plasma level of ir-ANP is regulated by blood volume status, and that the renal responsiveness to ANP, at least in part, contributes to water and sodium retention in NS.     

Plasma concentration of atrial natriuretic peptide in different phases of Korean hemorrhagic fever

Korean hemorrhagic fever (KHF) is an epidemic viral disease characterized by high fever, hemorrhagic tendency and renal failure, and by hemorrhages of right atrium and renal medulla as well as necrosis of anterior hypophysis. Plasma immunoreactive atrial natriuretic peptide (irANP) levels of 15 patients in the oliguric phase was 94.8 +/- 8.4 pg/ml (mean +/- SEM), 80% higher than of the normal control group (53.0 +/- 4.7 pg/ml; n = 28). In the diuretic phase it declined to 63.7 +/- 5.3 pg/ml (n = 26). Plasma renin activity (PRA) in the oliguric phase was 19.0 +/- 1.3 ng AI/ml/h, and in the diuretic phase 5.3 +/- 0.9 ng AI/ml/h, significantly higher than the control value (2.5 +/- 0.1 ng AI/ml/h). Elevations of irANP and PRA were not correlated in each group. Also systemic blood pressure as well as heart beats were significantly increased in the oliguric phase. These findings suggest that the increased irANP may have resulted from increased circulatory volume and that the ANP secretory process may not be affected by the disease.     

Changes in plasma atrial natriuretic peptide concentration during heart transplantation.

Examination of changes in plasma atrial natriuretic peptide (ANP) concentrations during heart transplantation may provide important information about factors influencing plasma ANP in patients with severe heart failure. Serial changes in plasma ANP during heart transplantation, and atrial content of ANP in native and donor atria, were measured in 12 patients. Preoperative plasma ANP was elevated in all patients (387 +/- 77 pg/mL), whereas atrial content of ANP in native atria was reduced (0.36 +/- 0.082 micrograms/mg protein). Preoperative plasma ANP did not correlate with hemodynamics, but was negatively correlated with creatinine clearance (r = -0.76, P < .01). Intraoperative plasma ANP prior to transplantation was strongly correlated with intraoperative plasma ANP after transplantation (r = 0.84, P < .001). Although postoperative plasma ANP was reduced from preoperative plasma ANP by 75%, these two measurements were also significantly correlated (r = 0.70, P < .02). Postoperative plasma ANP was not correlated with hemodynamics, but was negatively correlated with both creatinine clearance (r = -0.65, P < .05) and content of ANP in the native atria (r = -0.75, P < .01). Multiple linear regression analysis suggested that up to 85% of the variability of early postoperative plasma ANP could be accounted for by the variability in these latter two parameters. The decrease in native atrial ANP content, in the context of elevated plasma ANP concentration, is consistent with prior animal studies suggesting that severe heart failure induces cellular adaptations favoring accelerated ANP synthesis and secretion (with resultant reduction in tissue content).(ABSTRACT TRUNCATED AT 250 WORDS)     

Cardiovascular effects of human atrial natriuretic peptide during pediatric renal transplantation

BACKGROUND:We evaluated the cardiovascular effects of human atrial natriuretic peptide (hANP) in the pediatric recipients undergoing renal transplantation. METHODS: Anesthesia was maintained by inhalation of nitrous-oxide and isoflurane in oxygen. Intravenous infusion of hANP at a rate of 0.05 microg x kg(-1) x min(-1) was started on the anastomosis of the renal artery after the fresh frozen plasma had been loaded to achieve PCWP above 17 mmHg. We examined cardiovascular changes by using a pulmonary artery catheter and transesophageal echocardiography. The measurements were done before and after 15 minutes of hANP infusion. RESULTS: An increase in CI and a reduction in PCWP were significant. CONCLUSIONS: The low-dose infusion of hANP was useful in pediatric recipients undergoing renal transplantation for the optimal anesthetic care in view of the improvement of cardiovascular functions.     

Plasma alpha-human atrial natriuretic polypeptide levels during surgery for pheochromocytoma]

We measured plasma alpha-human atrial natriuretic polypeptide (alpha-hANP) and catecholamine concentrations during anesthesia and surgery for pheochromocytoma in five patients ranging in ages from 19 to 69. Plasma catecholamine concentrations and systemic blood pressure increased extremely during surgical manipulation of the tumor, while plasma alpha-hANP levels did not change even during surgical manipulation or after removal of the tumor as compared with preanesthetic values. Our findings suggest that plasma alpha-hANP levels were unchanged during anesthesia and surgery for human pheochromocytoma.