Comparison of serum beta 2-microglobulin and 24 hour urinary creatinine clearance as a prognostic factor in multiple myeloma

A new staging system for multiple myeloma (MM) has utilized serum concentrations of beta2-microglobulin (Sbeta2M) and albumin as important prognostic factors for survival. Since Sbeta2M is an indicator of glomerular filtration rate, we compared the prognostic values of Sbeta2M and 24-hr urinary creatinine clearance (Ccr) in patients with MM. We retrospectively reviewed the records of 170 MM patients from January 1996 to November 2003 whose 24-hr urinary Ccr was available at the time of diagnosis. We found that pretreatment Sbeta2M was inversely related to Ccr (Spearman's correlation coefficient=-0.787). In univariate analysis, the hazard ratio (HR) of death was 1.043 (p<0.001) for Sbeta2M and 0.985 (p<0.001) for Ccr. Multivariate analysis showed that Sbeta2M (HR 1.030, p=0.010) and Ccr (HR 0.993, p=0.059) were significant prognostic factors in patients' survival. In conclusion, 24-hr urinary Ccr may be utilized for staging of patients with MM.     

Serum Cystatin C is a Potential Endogenous Marker for the Estimation of Renal Function in Male Gout Patients with Renal Impairment

Serum creatinine level is the most commonly used indices for assessment of glomerular filtration rate (GFR), even though these indices have been shown to have some limitations in clinical practice. We investigated the diagnostic efficacy of serum cystatin C compared to that of serum creatinine levels and identified the relating factors associated with changes in serum cystatin C levels in gout patients with renal impairment. A total of 68 gouty patients with renal impairment were enrolled in this study. Diagnostic efficacy of serum cystatin C levels was evaluated through non-parametric receiver operating characteristic (ROC) analysis. The risk factors for changes in serum cystatin C levels were confirmed using multivariate regression analysis. With 24-hr urine creatinine clearance (Ccr) as the reference for GFR, 1/cystatin C (r=0.702, P<0.001) showed a significantly higher correlation with Ccr than 1/creatinine (r=0.665, P<0.001). Multivariate correlation analysis demonstrated that the clinical parameters for increased serum cystatin C are a higher stage of chronic kidney disease, older age, use of allopurinol, and lower high density lipoprotein-cholesterol. The area under the curve (AUC) at ROC plots identified that of serum cystatin C was significantly greater than that of serum creatinine (AUC 0.804 of cystatin C and AUC 0.745 of creatinine). The study suggests that serum cystatin C is a reliable endogenous marker for the assessment of renal function or GFR in gout patients with renal impairment.     

The effect of saline infusion and hemorrhage on glomerular filtration pressure and single nephron filtration rate

Summary Single nephron filtration rate (GFRs) and effective glomerular filtration pressure (EFP) measured as the difference between intratubular stop-flow (SFP) and free-flow pressures (FFP), were determined in control rats and following saline infusion or hemorrhage. Infusion of isotonic or 4% NaCl increased EFP and GFRs without significantly affecting TF/P inulin. These findings could not be related to changes in arterial blood pressure. Controlled bleeding produced a marked decrease in EFP and in GFRs, again without significant change in TF/P-inulin. In both infusion and hemorrhage the change in GFRs was disproportionately greater than the change in EFP. Analysis of the components of the filtration process suggests that elevation of EFP is attended by an increase in permeability of the filtering membrane. This sensitive dependence of GFRs upon EFP, combined with a demonstrated constancy of total kidney GFR (GFR_T) over a wide range of urine concentrations and flow rates, connotes a close regulation of EFP in this experimental animal.Supported by Deutsche Forschungsgemeinschaft.     

Function of juxtamedullary nephrons in normotensive and chronically hypertensive rats

Summary The function of juxtamedullary nephrons was investigated by micropuncture of long loops of Henle at the exposed papilla in normal rats and in the untouched kidney of rats with experimental hypertension (unilateral Goldblattclip). With increasing blood pressure (range from 90–190 mm Hg) a continuous rise in juxtamedullary single nephron glomerular filtration rate was observed. Juxtamedullary single nephron GFR averaged 60×10^–6 ml/min/g K.W. in the control group (mean arterial blood pressure 116 mm Hg) and 114×10^–6 ml/min/g K.W. in the hypertensive group (mean arterial blood pressure (164 mm Hg). There was no change in superficial single nephron GFR (30×10^–6 ml/min/g K.W.) but a slight increase in total kidney GFR from 1.07 to 1.28 ml/min g K.W. In both the normotensive and the hypertensive animals, tubular fluid-to-plasma (TF/P) inulin ratio and intratubular flow rate in the descending limb of the long loops of Henle were not statistically different from those found in the ascending limb. Intratubular flow rate in the hypertensive rats was twice as high as in the controls; the mean TF/P inulin ratios in the two groups did not differ from each other. Appearance time of lissamine green in the long loops of Henle and in the collecting ducts was shortened in the hypertensive animals. It is concluded that there is no autoregulation of glomerular filtration rate in juxtamedullary nephrons. The increased juxtamedullary GFR may contribute to the elevated urinary excretion of the unclipped kidney in hypertensive rats.This paper was presented before the German Physiological Society, Mainz, March 1969 [11].     

Development of glomerular filtration rate and electrolyte and osmolal clearance in the late-embryonic and newly hatched chicken

Summary Techniques have been developed for collection of urine in embryonic and newly hatched chickens for the purpose of studying the development of renal function.The reliability of EDTA-⁵¹Cr as a substitute for inulin-¹⁴C in the determination of GFR was studied. Since inulin and EDTA-⁵¹Cr clearances in the hatched chicken averaged 1.61±0.23 (S.E.) ml/min per kg body weight and 1.58±0.27 ml/min per kg body weight, respectively, EDTA-⁵¹Cr clearance was considered a suitable measure of GFR.GFR increased significantly in the first few days after hatching. Filtration rate was 0.068±0.008 (S.E.) ml/min per g kidney weight in the embryo and increased to 0.148±0.008 ml/min per g shortly after hatching. By nine days after hatching GFR had risen to 0.290±0.015 ml/min per g, a value comparable to that reported for the adult.Clearances of sodium, potassium, chloride and total osmolyte also increased with age. When these clearances were corrected for changing glomerular filtration rates the embryonic chicks were found to excrete a greater percentage of the filtered load. These results show that adult levels of glomerulo-tubular balance are not attained until after hatching.A preliminary report of this work has already been published [3].     

The effects of running, environment, and attentional focus on athletes' catecholamine and cortisol levels and mood

This study was designed to examine some of the psychoneuroendocrine effects of exercise-induced emotional experiences and the mediating effects of environmental setting and subjects' attentional focus. Trained runners were tested during an outdoor run and two indoor treadmill running conditions. Excretions of catecholamines and Cortisol significantly increased after all running conditions but not after a control condition. Results indicate that patterns of endocrine and concomitant emotional change through exercise differ when environmental setting and attentional focus are altered in such a way that a normally pleasant task such as running becomes tedious and negatively evaluated. These findings support the notion that setting, attention, and cognitive appraisal may alter the emotional experience associated with physical exercise.     

Theoretical analysis of the transient thermal clearance method for regional blood flow measurement

In the noninvasive transient thermal clearance method a metal plate at room temperature is attached to the investigated skin. The plate is thermally insulated from the environment, and so the tissue temperature, after an initial decrease, is increased at a rate which depends both on heat convection by blood and on tissue thermal conductivity. The corresponding bioheat conductivity equation is solved and the dependence of plate temperature on time and on blood flow discussed. It is shown that, for an appropriate choice of metal and plate thickness, regional blood flow can be derived from temperature/time curves.     

Single glomerular filtration rate of superficial and Juxta-medullary nephrons in the rat during different types of arterial hypertension

Summary The single nephron glomerular filtration rate (SNGFR) of superficial (S) and juxtamedullary (JM) nephrons were measured using¹⁴C-ferrocyanide infusion technique in rats under 3 different states of hypertension: acute hypertensions obtained either by bilateral carotid clamping (CC) or by contralateral renal ischemia (CI), and chronic Goldblatt hypertension. The juxtaglomerular index (JGI) was determined on the experimental kidneys.During acute hypertensions the JGI was normal, the granularity being more marked for the superficial than for the deep cortex. SNGFRs were higher in the JM (CC=39.2±3.4 SE nl/min; CI=41.0±4.5) than in the S (CC=30.3±2.5 CI=30.3±3.0) nephrons. These values are not different from those of normal rats. In the untouched kidney of Goldblatt rats the JGI was equal to zero. There was a general increase in SNGFRs. This increase was more marked for the S than for the JM nephrons, and the SNGFRs equalized in these two categories of nephrons (S=73.0±8.4; JM=74,7±8.2).From these observations, it is suggested that the renin content of the juxtaglomerular apparatus may play some role in the absolute value and intrarenal distribution of SNGFRs.This work was supported in part by a grant D.G.R.S.T. No. 7172 2726.Chargé de recherches à l'INSERM.     

Effects of leg covering in humans on muscle activity and thermal responses in a cool environment

Thermal responses and muscle performance in humans were studied during rest and exercise in a cool environment with different clothing distributions over the legs. Nine female subjects were exposed to 5°C wearing shorts (SS), trousers with long legs (LL) or trousers with one long leg and one short leg (LS: LSc covered leg, LSu uncovered leg). The subjects also wore T-shirts and long-sleeved shirts. The subjects were seated for 60 min and after this they performed light stepping exercise for a further 60 min. Rectal temperature (T _re) and skin temperature from seven (LL, SS) or nine sites (LS) were measured continuously. Surface electromyography (EMG) from three muscles (biceps femoris, gastrocnemius and tibialis anterior) were recorded during the exercise from six subjects. Integrated EMG (iEMG) and mean power frequency (MPF) were used to describe muscle activity. The T _re was virtually unchanged during rest in every ensemble, whereas during exercise T _re was significantly lower in SS than in LL. Mean skin temperature decreased during rest in every ensemble, being significantly lower in SS than in LL. After the rest period local T _sk of thigh and calf were significantly lower in SS than in LL and they were also lower in LSu than in LSc. At the beginning of the exercise the iEMG of the tibialis anterior muscle in SS and LL averaged 84 (SEM 7) and 64 (SEM 3) V (P < 0.05), respectively. Respective values for LSu and LSc were 86 (SEM 9) and 66 (SEM 6) V (P < 0.05). The MPF of the tibialis anterior muscle was significantly higher in LL 102 (SEM 5) Hz than in SS 90 (SEM 5) Hz (P < 0.05) and similarly the MPF of the gastrocnemius muscle was also higher in LL 111 (SEM 5) Hz than in SS 100 (SEM 5) Hz (P < 0.05). It was concluded that exposing bare legs to a cool environment enhanced the motor unit activity in relation to covered legs. This would suggest that wearing shorts in a cool environment may, at the beginning of exercise, result in higher (about 25%) EMG activity and this may reflect increased muscle strain in comparison with wearing long trousers. Our results showing a unilateral increase in EMG activity during unilateral cooling suggest that the increase of strain is restricted to the uncovered part of the limb.     

The independent roles of temperature and thermal perception in the control of human thermoregulatory behavior

The present study independently evaluated temperature and thermal perception as controllers of thermoregulatory behavior in humans. This was accomplished using a self-paced exercise and heat stress model in which twelve physically active male subjects exercised at a constant subjective rating of perceived exertion (16, ‘hard - very hard’) while their face was thermally and non-thermally cooled, heated, or left alone (control trial). Thermal cooling and heating were achieved via forced convection, while non-thermal cooling and heating were accomplished via the topical application of menthol and capsaicin solutions. Evidence for thermoregulatory behavior was defined in terms of self-selected exercise intensity, and thus exercise work output. The results indicate that, in the absence of changes in temperature, non-thermal cooling and warming elicited thermal sensory and discomfort sensations similar to those observed during thermal cooling and warming. Furthermore, the perception of effort was maintained throughout exercise in all trials, while the initial and final exercise intensities were also similar. Thermal and non-thermal cooling resulted in the highest work output, while thermal warming the lowest. Non-thermal warming and control trials were similar. Heart rate, mean skin and core (rectal) temperatures, and whole body and local (neck) sweat rates were similar between all trials. These data indicate that changes in temperature are not a requirement for the initiation of thermoregulatory behavior in humans. Rather, thermal sensation and thermal discomfort are capable behavioral controllers.     

The effects of incremental submaximal exercise on circulating leukocytes in physically active and sedentary males and females

To study the effects of exercise on circulating leukocytes and leukocyte subsets, physically active (n = 32) and sedentary (n = 32) male and female subjects were randomly assigned to an exercise or control condition. Exercise involved a continuous incremental protocol consisting of cycling for three periods of 6 min at power outputs corresponding to 55%, 70% and 85% maximal oxygen uptake ( . Blood samples were drawn from a venous catheter at baseline, and at 6 min, 12 min, and 18 min after beginning the exercise and 2 h following completion of exercise. Resting- and exercise-induced alterations in total leukocytes were independent of gender and subject fitness level. Relative to baseline, each increment in workload resulted in a rapid increase in the number of circulating leukocytes. Increases in neutrophils, lymphocytes and monocytes accounted for the exercise-induced leukocytosis. With regard to lymphocytes, exercise resulted in a significant increase in the number of T cells (CD3⁺), T helper cells (CD4⁺), T suppresser (CD8⁺) and natural killer (NK) cells (CD3^–/CD16⁺/CD56⁺). The largest percentage increase occurred in the NK cell population. The CD4⁺: CD8⁺ ratio decreased (P < 0.001) throughout exercise due to a larger increase in the number of CD8⁺ cells relative to CD4⁺ cells. An exercise-induced neutrophilia, lymphocytopenia, and eosinophelia was observed 2 h into recovery. Exercise resulted in significant increases in plasma epinephrine and norepinephrine levels. There was no indication of a hypothalamic-pituitarty-adrenal response during exercise. The results indicate that the rapid, albeit transient, alteration in the number of circulating leukocytes during and following an acute progressive incremental exercise test are independent of gender and fitness.     

中国南方地区正常人群血清肌酐水平的变化其临床意义

目的： 探讨中国南方地区正常人群各年龄阶段的血清肌酐水平变化,并初步建立酶学检测中国人群血清肌酐的参考范围。方法: 采用酶法检测2 000例不同年龄阶段的健康人群血清肌酐水平,其中男性1 200例,女性800例,年龄从1个月至80岁,通过统计学方法分析各年龄阶段人群的血清肌酐水平。结果: 正常人群的血清肌酐水平随年龄增长而增高,在同一年龄组中,两性之间的血清肌酐水平存在显著差异。10岁以下的男女血清肌酐分别为(26.67±7.84、25.20±6.40)μmol/L;11-20岁组分别为(68.26±12.74、54.72±7.78)μmol/L; 21-30岁组分别为(77.74±8.09、57.17±8.18)μmol/L; 31-40岁组分别为(79.35±10.36、55.65±9.07)μmol/L;41-50岁组分别为(81.21±12.86、62.40±10.91)μmol/L;51-60岁组分别为(79.49±11.54、61.11±12.65)μmol/L;61-70岁组分别为(83.87±16.74、60.62±11.47)μmol/L;年龄大于71岁组分别为(96.61±25.26、64.55±12.01)μmol/L。结论: 不同年龄正常人群的血清肌酐水平存在显著的差异;在同一年龄阶段,男女之间也存在显著的差异,在临床诊断中应该建立对应的参考标准。     

Glomerular Filtration Rate Measured by 51Cr-EDTA Clearance: Evaluation of Captopril-Induced Changes in Hypertensive Patients with and without Renal Artery Stenosis

INTRODUCTION:

Renal artery stenosis can lead to renovascular hypertension; however, the detection of stenosis alone does not guarantee the presence of renovascular hypertension. Renovascular hypertension depends on activation of the renin-angiotensin system, which can be detected by functional tests such as captopril renal scintigraphy. A method that allows direct measurement of the baseline and post-captopril glomerular filtration rate using chromium-51 labeled ethylenediamine tetraacetic acid (⁵¹Cr-EDTA) could add valuable information to the investigation of hypertensive patients with renal artery stenosis. The purposes of this study were to create a protocol to measure the baseline and post-captopril glomerular filtration rate using ⁵¹Cr-EDTA, and to verify whether changes in the glomerular filtration rate permit differentiation between hypertensive patients with and without renal artery stenosis.

METHODS:

This prospective study included 41 consecutive patients with poorly controlled severe hypertension. All patients had undergone a radiological investigation of renal artery stenosis within the month prior to their inclusion. The patients were divided into two groups: patients with (n=21) and without renal artery stenosis, (n=20). In vitro glomerular filtration rate analysis (⁵¹Cr-EDTA) and ^99mTc-DMSA scintigraphy were performed before and after captopril administration in all patients.

RESULTS:

The mean baseline glomerular filtration rate was 48.6±21.8 ml/kg/1.73 m² in the group wuth renal artery stenosis, which was significantly lower than the GFR of 65.1±28.7 ml/kg/1.73m² in the group without renal artery stenosis (p=0.04). Captopril induced a significant reduction of the glomerular filtration rate in the group with renal artery stenosis (to 32.6±14.8 ml/ kg/1.73m², p=0.001) and an insignificant change in the group without RAS (to 62.2±23.6 ml/kg/1.73m², p=0.68). Scintigraphy with technetium-99m dimercapto-succinic acid (DMSA) did not show significant differences in differential renal function from baseline to post-captopril images in either group.

CONCLUSIONS:

Captopril induced a decrease in the GFR that could be quantitatively measured with ⁵¹Cr-EDTA. The reduction is more pronounced in hypertensive patients with RAS.     

The effects of passive heating and head-cooling on perception of exercise in the heat

The capacity to perform exercise is reduced in a hot environment when compared to cooler conditions. A limiting factor appears to be a higher core body temperature (T (core)) and it has been suggested that an elevated T (core) reduces the drive to exercise, this being reflected in higher ratings of perceived exertion (RPE). The purpose of the present study was to determine whether passive heating to increase T (core) would have a detrimental effect on RPE and thermal comfort during subsequent exercise in the heat and whether head-cooling during passive heating would attenuate these unpleasant sensations of an elevated T (core) during subsequent exercise in the heat. Nine physically-active, non-heat-acclimated volunteers [6 males, 3 females; age: 21 +/- 1 year, [Formula: see text] 50 +/- 9 ml kg(-1).min(-1), peak power output: 286 +/- 43 W (mean +/- SD)] performed two 12-minute constant-load cycling tests at 70% [Formula: see text] in a warm-dry environment (34 +/- 1 degrees C, relative humidity <30%) separated by a period of passive heating in a sauna (68 +/- 3 degrees C) to increase T (core). In one trial, subjects had their head and face cooled continually in the sauna (HC), the other trial was a control (CON). Passive heating increased T (core) by 1.22 +/- 0.03 degrees C in the CON and by 0.75 +/- 0.07 degrees C in the HC trial (P < 0.01). Passive heating increased weighted mean skin temperature (T (msk)) in both the CON and HC trials (P < 0.01), however, head-cooling lowered T (msk) during passive heating (P < 0.05). Exercise time following passive heating was reduced in both the CON and HC trials (P < 0.05). Passive heating increased RPE (P < 0.01), however, RPE was lower following passive heating with head-cooling (P < 0.05). There was a significant correlation between T (core) and RPE (r = 0.82, P < 0.001). In conclusion, our results suggest increased RPE during exercise in the heat is primarily due to the increase in T (core). Furthermore, head-cooling attenuates the rise in T (core) and the effect on RPE is proportional to the rise on T (core).     

Effect of exercise on thermal comfort during hypothermia

Subjective measures of thermal comfort were made in 12 male subjects who exercised intermittently during reduction of core temperature. Cold discomfort was found to be inversely proportional to work rate in the range studied of up to 65% aerobic capacity. This relationship was independent of the effect of the exercise on body temperatures. It occurred while core temperature fell and mean skin temperature either fell, remained steady at low levels or rose again towards normal. Possible mechanisms are reviewed and it is concluded that this effect of voluntary exercise, like that of shivering, is psychological.     

The effect of the rate of heat storage on serum heat shock protein 72 in humans

Hsp72 concentration has been shown to be higher in the serum (eHsp72) of runners with symptoms of heat illness than in non-ill runners. Recently, it has been suggested that the rate of heat storage during exercise in the heat may be an important factor in the development of heat stroke. Therefore, we compared the effect of two rates of heat storage on eHsp72 concentration during exercise in which subjects reached the same final core temperature. We hypothesized that with a lower rate of heat storage the increase in eHsp72 would be attenuated compared to a higher rate of heat storage. Nine heat acclimated subjects performed two exercise trials in a counterbalanced order in the heat (42°C, 30% relative humidity). The trials consisted of walking on a treadmill (~50% VO ₂ peak) dressed in military summer fatigues until rectal temperature reached 38.5°C. A high rate of heat storage (HS, 1.04 ± 0.10 W m⁻² min⁻¹, mean ± SE) occurred when subjects walked without cooling. To produce a lower rate of heat storage (LS, 0.54 ± 0.09 W m⁻² min⁻¹) subjects walked while wearing a water-perfused cooling vest underneath clothing. eHsp72 increased pre- to post-exercise (P < 0.05) but there was no difference (P > 0.05) in eHSP between the two rates of heat storage (LS 1.25 ± 0.73 to 2.23 ± 0.70 ng ml⁻¹, HS 1.04 ± 0.57 to 2.02 ± 0.60 ng ml⁻¹). This result suggests that eHsp72 is a function of the core temperature attained rather than the rate of heat storage.     

Effects of prostaglandin E2 on excretion and reabsorption of sodium and fluid in rat kidneys (micropuncture studies)

Summary The effects of i.v. infusions of Prostaglandin E₂ on renal excretion of sodium and fluid were investigated in rats. Increasing diuresis was observed at infusion rates from 10 to 100 ng/min·100 g BW. Higher rates depressed the arterial blood pressure and urinary excretion rates. At 100 ng PGE₂/min·100 g BW urinary flow rate increased approximately 3 times and sodium excretion approximately 8–10 times above the control level. The urine/plasma concentration ratio of Na averaged 1.7 compared with 0.5 in controls. Potassium excretion, however, was only slightly enhanced.The effects on sodium and fluid excretion were not correlated with changes of total kidney GFR. Single nephron GFR of superficial nephrons remained unchanged during the PGE₂ infusion.Fractional proximal reabsorption of sodium and fluid, calculated from endproximal tubular fluid/plasma concentration ratios of Na and Inulin, were not inflenced by PGE₂. Transtubular net movements, calculated from split drop half time, were not significantly affected, too. Tubular transit time, however, was shortened, and fractional proximal reabsorption was decreased, when calculated fromt1/2 andT. This, too, indicates thatt1/2 andT do not always sufficiently define the fractional reabsorption.The normal decrease of the TF/P ratio of Na along the distal convolution is reduced under the influence of PGE₂. Approximately 2% of the filtered Na remain unreabsorbed in the distal convolution in addition to the amount found in controls. The high Na concentration in the final urine is established in the collecting ducts by an ADH like action.Preliminary reports of the results were presented in part at the 33rd meeting of the Deutsche Pharmakologische Gesellschaft in Heidelberg 1970.     

The influence of glomerular and interstitial factors on the serum creatinine concentration in renal amyloidosis

Summary 48 cases of renal amyloidosis (grade I–IV) were investigated morphologically (point-counting method). Statistically significant positive correlations exist between relative interstitial volume and serum creatinine concentration at the time of biopsy. In amyloidosis there are furthermore connections (positive rank correlations) between the extent of glomerular amyloidosis and renal insufficiency, although single cases of grade III show normal serum creatinine concentrations if the interstitium is not enlarged. With regard to interstitial alterations only fibrosis, not amyloid masses, seems to influence renal function, especially in the case of predamaged glomeruli (grade II to IV). The diminished renal function — reduction of the glom. filtr. rate — may be explained in the case of interstitial fibrosis by slowing of renal blood flow caused by a decreasing cross-sectional area of postglomerular vessels.Renal insufficiency seems to depend upon both the glomerular and the interstitial factor, but in grades II–IV the interstitial fibrosis is thought to be of more importance for renal function.Supported by the Deutsche Forschungsgemeinschaft     

The effect of exercise training on restraint ulcers in rats

The effect of chronic treadmill running on susceptibility to restraint-cold-induced ulcers was studied in two strains of rats: Long-Evans and Sprague-Dawley. Runners were progressively trained for 8 weeks, reaching a rate of 1 mph for 1 hr daily, 5 days per week after the 4th week. Walkers were exposed to the treadmill environment 3 days per week (0.2 mph for 10 min). Sedentary groups remained in their home cages. After 8 weeks the rats were starved for 24 hrs, immobilized in restraint cages and placed in the refrigerator (5° C) for 4 hrs. Animals were then sacrificed and their stomachs examined for ulcerative lesions. No significant differences in number of ulcers or ulcer indexes per stomach were found between groups within each rat strain or between strains. These results suggest that treadmill running provides no protection against gastric ulceration induced by restraint-cold stress. The complex variables involved in ulcer research are discussed and suggestions presented for future work on the anti-ulcer effect of exercise.Supported in part by the University of Nebraska Research Council Summer Fellowship.     

Effect of barbiturates on GFR and fluid reabsorption along proximal convoluted tubules and loops of henle in rats

Summary In the present study we investigated the possibility that GFR and fluid reabsorption are systematically altered by dose and/or structure of different barbiturate compounds. The results show that filtration and absorption rates are identical in rats anaesthetized with 100 or 150 mg/kg BW. Elevating the administered amount by intravenous injections of inactin did not alter renal functions compared to values measured immediately before the additional administration. No differences of GFR and absorption rates were noted when the effect of inactin, amytal, and nembutal in doses necessary to induce and maintain anaesthesia was compared. Absolute and fractional absorption was observed to decrease by 20 to 25% in the first 3 h after induction of anaesthesia independent of the anaesthetic used. Our results suggest that filtration and absorption rates are not systematically modified by specific anaesthetic effects, at least not when doses are kept close to the necessary minimum.Work performed during tenure of an Alexander von Humboldt-Dozentenstipendium.