Der Einflu� von �nderungen des Urin-pH auf die Ausscheidung von Aminos�uren an der isoliert perfundierten Rattenniere

Braun, W.; Zschaler, W.; Weiss, C

doi:10.1007/bf00536798

Cited by 10 publications

(9 citation statements)

References 23 publications

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“…Furthermore, it will be necessary to rule out the possible influence of decreased tubular amino acid transport by substances retained in the extracellular fluid, and other factors which based on results of micropuncture studies seem important from this aspect [3][4][5]7,[10][11][12]14,17],…”

Section: Discussionmentioning

confidence: 99%

Renal Clearance of Amino Acids in Patients with Severe Chronic Renal Failure

Nádvorníková

Schück

Malý

et al. 1978

Nephron

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The renal clearance of 21 amino acids was investigated in 5 patients with chronic renal failure (inulin clearance ≈ 5–10ml/min) during the 6-week administration of a low-protein diet. The results were compared with values obtained in 6 volunteers. The renal clearance of all investigated amino acids (with the exception of Asp, His, Tau) did not differ significantly from healthy controls. The excretion fraction (amino acid clearance /inulin clearance 100) was in all investigated amino acids significantly higher than incontrols with the exception of Tau. The excretion fractions of Asp, Ser, Cys, Tyr, His, Thr, Tau and Gly were, on average, above 20%.The findings suggest that the fractional reabsorption of amino acids in residual nephrons is decreased.

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Section: Discussionmentioning

confidence: 99%

Renal Clearance of Amino Acids in Patients with Severe Chronic Renal Failure

Nádvorníková

Schück

Malý

et al. 1978

Nephron

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“…Except for the studies of Braun and Zschaler [1] and Weiss et al [20], the pre liminary observations of Maack et al [7], and our previous studies [13], the renal han dling of amino acids by perfused rat kidneys has not been evaluated. In one study [1], it was found that the amino acid clearance rose with the rising pH and that at a pH of 8, several amino acids were excreted in quan tities exceeding their filtered load.…”

Section: Discussionmentioning

confidence: 99%

“…In one study [1], it was found that the amino acid clearance rose with the rising pH and that at a pH of 8, several amino acids were excreted in quan tities exceeding their filtered load. Unfortu nately, even at urinary pH values lower than 6 the clearance of several amino acids was between 10 and 30% of the filtered load sug gesting an impairment oftubular function in their experimental model.…”

Section: Discussionmentioning

confidence: 99%

“…It is unlikely, however, that the near-normal amino acid perfusate concentrations used in this study would have induced these changes. Finally, it should be noted in passing that the defect in urinary acidification that may be mani fested by perfused kidneys [1,8] or that the abnormal vitamin D metabolism in chronic renal failure [14] could have contributed to enhance the clearance of amino acids.…”

Section: Discussionmentioning

confidence: 99%

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Functional Adaptation to Reduction in Renal Mass: Renal Handling of Amino Acids by Isolated Perfused Remnant Rat Kidneys

Pérez¹,

Epstein²,

Rietberg³

et al. 1981

Kidney Blood Press Res

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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.

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“…No studies investigating an effect of altered pH on amino acid reabsorption of the proximal convoluted tubule have been undertaken and only one study of the effect of altered acid/base conditions on renal amino acid clearances in the rat had been reported (Braun, Zschaler and Weiss, 1967). This study, in the isolated perfused rat kidney, showed that the clearances of amino acids from all transport groups rose dramatically when an increasingly alkaline vascular perfusate was used and clearances reached 200% of the glomerular filtration rate (GFR) in some cases.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Chronic Acid/Base Disturbances on Renal Amino Acid Clearances in the Rat

Galicek

Seow

1981

Aust J Exp Biol Med

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Summary.Since the few data available concerning the effect of acid/base disturbances on renal amino acid reabsorption were conflicting, and there were sound theoretical reasons for an effect, we have studied the clearance of endogenous amino acids in the rat in vivo under control conditions and after induction of either metabolic acidosis or alkalosis by administration of NH4CI or NaHCO3, respectively. The effectiveness of treatment was assessed by examination of plasma and urinary levels of HCO3, Cl, Na and K. It was found that the renal clearance of amino acids, measured during acidosis or alkalosis, did not differ from those found under control conditions, the majority of values being less than t% of the glomerular filtration rate. Thus, the amino acid reabsorptive mechanism appears unaffected by changes in the pH of the glomerular filtrate and/or by changes in tubular hydrogen ion secretion which would accompany such disturbances. These data are thus in agreement with findings during acidosis in man and in both acidosis and alkalosis in the dog. The findings are contrary to earlier reports from in vitro studies in the rat, and suggest the presence of severe functional impairment in the isolated perfused kidneys used in these earlier studies where very large changes in amino acid clearance were obtained.

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Der Einflu� von �nderungen des Urin-pH auf die Ausscheidung von Aminos�uren an der isoliert perfundierten Rattenniere

Cited by 10 publications

References 23 publications

Renal Clearance of Amino Acids in Patients with Severe Chronic Renal Failure

Renal Clearance of Amino Acids in Patients with Severe Chronic Renal Failure

Functional Adaptation to Reduction in Renal Mass: Renal Handling of Amino Acids by Isolated Perfused Remnant Rat Kidneys

The Effect of Chronic Acid/Base Disturbances on Renal Amino Acid Clearances in the Rat

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