摘要:

Since the discovery of the steroid hormone aldosterone nearly 35 years ago, our knowledge on the cellular actions of aldosterone is still incomplete. Most of the present physiological and biochemical knowledge about the antinatriuretic action was revealed by investigations on amphibian tight epithelia, in particular the toad urinary bladder. Less biochemical information was obtained from mammalian tissue such as microdissected renal tubules and cultured cells. In our opinion, it is questionable whether de novo synthesis of cell proteins – induced by aldosterone – can explain all of the hormonal effects to increase the Na+ transport. In the present paper we try to analyze the wide and contradictory field of biochemical data about the action of aldosterone on the increase in Na+ transport in renal cells in an attempt to incorporate this information into an extended working hypothesis. We suggest distinguishing principally between an early and a late biochemical response phase. We speculate that aldosterone may act by a two-step mechanism: the early and late aldosterone-induced prote

ISSN:1420-4096    

DOI:10.1159/000173139

出版商:S. Karger AG    

年代:1987

数据来源: Karger

摘要:

The intrarenal kallikrein-kinin system was studied during the acute phase of renovascular hypertension induced by renal artery constriction and during teprotide inhibition of kininase II in the dog. Kallikrein-like activity measured by both kininogenase and esterolytic assays, was increased during renal artery constriction (p < 0.5) and (p < 0.01). The administration of teprotide resulted in a further increase of renal cortical kallikrein-like activity and inhibited kininase II activity (p < 0.01). Following the inhibition of kininase II, the plasma concentration of kininogen was also significantly decreased (p < 0.0l). These results suggest that kininase II inhibition may increase levels of intrarenal and plasma kinins and that decreased degradation of kinin peptides may contribute significantly to the acute hypertensive effect of teprotide.

ISSN:1420-4096    

DOI:10.1159/000173140

出版商:S. Karger AG    

年代:1987

数据来源: Karger

摘要:

In previous intravital microscopic studies of the hydronephrotic split kidney a narrow segment in the efferent arteriole at its origin from the glomerulus was observed. In the present study in vivo techniques were combined with transmission electron microscopy of thin sections to investigate the structural basis for the luminal narrowing. At the point where the efferent arteriole leaves Bowman’s capsule prominent endothelial cells were found to bulge into the lumen of the vessel. These cells participate in the overall narrowing of the lumen at this site and appear to be responsible for the in vivo picture. However, the principal basis for the narrowing seems to be an extrinsic constriction of the vessel, possibly by extraglomerular mesangial cells located at the exit level. It is suggested that the outflow portion of the efferent arteriole may be an important site of control of glomerular blood flo

ISSN:1420-4096    

DOI:10.1159/000173141

出版商:S. Karger AG    

年代:1987

数据来源: Karger

摘要:

The effect of three aminoglycosides – gentamicin, netilmicin and amikacin – on renal acid excretion was studied in male rats treated with doses equivalent to those clinically used. The amikacin and netilmicin groups showed no important changes in the values of glomerular filtration rate (GFR), effective renal plasma flow (ERPF) and U/P inulin ratio during normal and acidotic conditions. The gentamicin group, however, showed a clear tendency to decreases in these functional parameters even in normal conditions, a finding that reinforces the concept that gentamicin is more nephrotoxic than other aminoglycosides. During normal conditions net acid excretion (BH) did not change with any of the three tested drugs. However, after an acute acid load BH markedly fell regardless of the antibiotic used. The capacity to elevate the urine-blood pCO2 was preserved after an alcaline overload, suggesting that the distal tubule was not significantly affected by aminoglycoside treatment. These data suggest that the clinical use of aminoglycosides during metabolic acidosis deserves close attention due to the possible deleterious effect that can emerge as the result of an inappropriate retention of acid lo

ISSN:1420-4096    

DOI:10.1159/000173142

出版商:S. Karger AG    

年代:1987

数据来源: Karger

摘要:

To examine the effects on protein and electrolyte reabsorption of reducing the energy supply to the proximal tubules, an inhibitor of the citric acid cycle, maleate (600 mg · kg-1), was administered to anesthetized dogs during continuous ethacrynic acid infusion. One hour after infusion, maleate reduced renal oxygen consumption from 128 ± 3 to 48 ± 6 µmol·min-1. Comparisons at similar GFR showed that maleate reduced bicarbonate reabsorption by 65%, chloride reabsorption by 60% and phosphate reabsorption by 90%. Tubular reabsorption of lysozyme, determined by the ‘trapped-label’ method, was reduced by 97%. Total protein excretion in urine increased from 0.12 to 1.0 mg·min-1 and was not associated with a significant increase in brush border and lysosome marker enzymes. However, by superimposing a carbonic anhydrase inhibitor, acetazolamide (100 mg·kg-1), electrolyte reabsorption was slightly further reduced but protein excretion increased to 2.7 mg·min-1, coincidentally with a dramatic increase in enzyme excretion: approximately 20-fold in the brush border enzymes, alanine aminopeptidase and alkaline phosphatase, and 10-fold in the lysosomal enzymes, acid phosphatase and N-acetyl-β-glucosaminidase. Our data indicate that maleate stops protein reabsorption without signs of acute tubular damage, whereas subsequent administration of acetazolamide results in tubular desquamation and alb

ISSN:1420-4096    

DOI:10.1159/000173143

出版商:S. Karger AG    

年代:1987

数据来源: Karger

摘要:

The effect of varying concentrations of substrate-free albumin (SFA) in the absence of exogenous substrate was investigated in the isolated perfused rat kidney. Consistent with starling relationship, there was a progressive decrease in glomerular filtration rate (GFR), from 778 ± 36to41 ± 17 µl/min · g, and a progressive increase in fractional sodium reabsorption (%TNa+), from 31.1 ± 0.9 to 82.6 ± 2.3%, when the mean SFA concentration in the perfusate was increased from 3 to 10 g/dl. Perfusate flow rate (PFR) remained constant at 30 ml/min · g as the GFR decreased. When the mean perfusate SFA concentration was decreased from 3 g/dl to 0, the anticipated decrease in %TNa+ occurred but the increase in GFR did not. PFR was also reduced by one half when SFA was not present in the perfusion medium. The reason for the anomalous behavior of GFR and PFR when SFA was omitted from the perfusion medium is not

ISSN:1420-4096    

DOI:10.1159/000173144

出版商:S. Karger AG    

年代:1987

数据来源: Karger

ISSN:1420-4096    

DOI:10.1159/000173145

出版商:S. Karger AG    

年代:1987

数据来源: Karger

ISSN:1420-4096    

DOI:10.1159/000173146

出版商:S. Karger AG    

年代:1987

数据来源: Karger

ISSN:1420-4096    

DOI:10.1159/000173138

出版商:S. Karger AG    

年代:1987

数据来源: Karger