摘要:

To date, the renal handling of amino acids by remnant kidneys remains undefined. We have determined the renal handling of eight amino acids using the isolated perfused rat kidney. 6 normal and 22 partially infarcted rat kidneys (16 stage III [contra-lateral kidney removed], and 6 stage II [contralateral kidney left intact] were evaluated at perfusate amino acid concentrations approximately ten times normal plasma levels. Despite the reduction in glomerular filtration rate, the urinary excretion of most amino acids in remnant kidneys tended to exceed that of controls. Fractional amino acid excretion by both stage II and III kidneys tended to be or was higher than that of controls. The findings indicate that the fractional reabsorption of amino acids by residual nephrons of remnant kidneys is decreased. Our observations suggest that the changes are unrelated to a functional adaptation to the uremic environment.

ISSN:1420-4096    

DOI:10.1159/000172822

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

The suitability of some commonly used experimental procedures for studying the effect of chronic alterations of sodium excretion on lithium clearance was examined in Wistar rats and Sprague-Dawley rats. The animals were maintained on diets with standardized sodium content for 10 days before the investigation. Urine flow and clearance values were measured in (1) awake unoperated rats, (2) awake catheterized rats and (3) anaesthetized rats of both strains. Awake unoperated and awake catheterized Wistar rats showed almost identical urine flows and clearances of sodium and lithium. Amytal anaesthetized Wistar rats showed significantly depressed urine flows and clearances of sodium, lithium and inulin as compared with awake rats. Awake unoperated and awake catheterized Sprague-Dawley rats showed almost identical clearance values but the urine flow rates were increased about fivefold in the awake catheterized Sprague-Dawley rats. Amytal anaesthetized catheterized Sprague-Dawley rats showed unchanged urine flows and clearance values as compared with awake rats. Inactin anaesthesia reduced the urine flows and clearance values in both Wistar rats and Sprague-Dawley rats. It is concluded that anaesthesia and surgery affect the kidney function to different degrees in different rat strains, amytal anaesthetized Sprague-Dawley rats being the least influenced. If exposure of the kidney is unnecessary, awake catheterized Wistar rats offer a suitable experimental procedure for determination of urine flow and urinary clearances of sodium and lithium.

ISSN:1420-4096    

DOI:10.1159/000172823

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

Renal handling of H2O, Na, and K during H2O diuresis was studied in the same healthy subjects on two occasions, after the administration of either 5 mg of the sulfonylurea, glipizide, or a placebo. Following glipizide, there was no significant overall change in creatinine clearance and the calculated rate of distal Na + K delivery (CH2O + C(Na+K)) in 9 individuals. However, the clearance of free water (CH2O) and the mean fraction of Na + K reabsorbed at the diluting site increased significantly from 8.5 ± (SEM) 0.8 to 9.8 ± (SEM) 0.8 ml/min/100 ml GFR (p < 0.02) and from 55 ± (SEM) 6 to 67 ± (SEM) 7% (p < 0.05), respectively. The mean rate of total Na and K excretion fell following glipizide (p < 0.05). Our results, in conjunction with the results from similar type studies, suggest that ingestion of glipizide and other sulfonylureas that lack antidiuretic properties increase CH2O, at least in part, by augmenting ion reabsorption at the diluting sites of the neph

ISSN:1420-4096    

DOI:10.1159/000172824

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

Rat tubuli were isolated both by the method of Krisko and by a modified method of Cook and Pickering; renal tubular basement membrane (TBM) was isolated by sonic disruption and by the method of Carlson. Using electron microscopy after negative staining, TBM of rat kidney isolated under these different conditions was shown to be a fine meshwork. Strands of the meshwork were interwoven, apparently enclosing pores to make up whole basement membrane. These findings are compared with our previous observation that glomerular and alveolar basement membranes were made up of a similarly fine meshwork.

ISSN:1420-4096    

DOI:10.1159/000172825

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

The effect of external Ca2+ on p-aminohippurate (PAH) transport was examined using rat kidney cortical slices. External Ca2+ increased the initial rate of PAH uptake, markedly enhanced its maximal accumulation at steady-state conditions and depressed the efflux. Kinetic studies revealed that increasing external Ca2+ from 0 to 2.5 mM resulted in an increase in the Vmax of transport, while the apparent Km values remained constant. When the intracellular Na+ levels of the slices were equal, PAH accumulation was increased in the presence of Ca2+.A divalent cation such as Ba2+, Mn2+ or Sr2+ enhanced PAH accumulation to at least the same degree as Ca2+. While Mg2+ had no effect, La3+ exhibited a little stimulatory effect on the PAH accumulation. We suggest that the stimulatory action of Ca2+ on PAH accumulation is in part dissociated from that of Na+ gradient and that Ca2+ can be substituted by Ba2+, Mn2+ and Sr2+ with regard to the stimulation of PAH accumulation.

ISSN:1420-4096    

DOI:10.1159/000172826

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

The relationship between renin activity in renal venous plasma and in renal interstitial fluid, as reflected in the hilar lymph, was observed. Control measurements in 28 dogs demonstrated that renin levels in the hilar lymph were 3.5 ± (SEM)0.4 times higher than in renal venous plasma and 6.1 + 1.0 times higher than in arterial plasma. Renin activity was increased to varying levels by raising ureteric pressure and by the administration of different doses of furosemide. Under all conditions, the changes in renin activity in renal venous plasma and in the interstitium, as reflected in the hilar lymph, were in parallel although often more marked in the hilar lymph. Thus, the study shows that under conditions of increased renin release, the interstitial renin activity rises in consort with increases in arteriovenous plasma differences. This increase in interstitial renin activity occurred even under circumstances when renal blood flow is known to increase, thereby suggesting that angiotensin generated in the interstitium may have little effect on the cortical arteriolar caliber

ISSN:1420-4096    

DOI:10.1159/000172827

出版商:S. Karger AG    

年代:1981

数据来源: Karger

ISSN:1420-4096    

DOI:10.1159/000172828

出版商:S. Karger AG    

年代:1981

数据来源: Karger

ISSN:1420-4096    

DOI:10.1159/000172829

出版商:S. Karger AG    

年代:1981

数据来源: Karger

ISSN:1420-4096    

DOI:10.1159/000172821

出版商:S. Karger AG    

年代:1981

数据来源: Karger