摘要:

Brush border membranes (BBM) have been prepared from fresh samples of normal human kidney cortex and compared to that from mouse, rat, and rabbit. Human BBM presents a sodium dodecyl sulfate gel electrophoresis protein pattern similar to that of the animal species with 22 proteins having the same molecular weight (MW). Incubation with inorganic 32P reveals a phosphate-binding protein (MW 78,000) common to the animal species. However, the binding capacity is lower in man: 4.3 ± 2.2 pmol Pi/mg protein compared to 9.9 ± 2.1, 29.7 ± 4.3, and 31.1 + 5.2 in rabbit, mouse, and rat, respectively. The MW of the binding protein corresponds to that of the monomer of alkaline phosphatase. Alkaline phosphatase activity follows the same increasing order in the four species. The Na gradient-dependent Pi uptake by human BBM vesicles is low: Vmax is 0.90 + 0.05 nmol/mg/ 20 s compared to 1.3 + 0.1, 1.5 + 0.2, and 5.2 + 0.2 in rabbit, mouse, and rat, respectively. However, the Km values are within the same range for the four speci

ISSN:1420-4096    

DOI:10.1159/000172925

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

Cortical and juxtamedullary glomeruli of the human kidney were isolated by sieving. Verapamil, a calcium inhibitor, was added to a suspension of the glomeruli. The vasomotor response was measured by a video analyser. We were thus able to determine the modiñcation of the cortical and juxtamedullary glomeruli surface area. Only the cortical glomeruli became vasodilated in response to the calcium inhibitor

ISSN:1420-4096    

DOI:10.1159/000172926

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

The study of diabetic nephropathy in experimental animals generally relies on the chemical induction of the diabetic state. Streptozotocin is commonly employed to that end; however, streptozotocin has an inherent nephrotoxic potential. We studied the effects of both streptozotocin, and diabetes on the kidneys of rats given streptozotocin 60 mg/kg, which was sufficient to induce severe diabetes. Our studies, which utilized both transmission and scanning electron microscopy, considered the pharmacokinetics of streptozotocin in renal tissue, as well as the effect of insulin treatment. Renal tissue kinetics were altered by occluding the renal hilum of one kidney during, and for 5 min after, the administration of streptozotocin. We found that, in contrast to alloxan, streptozotocin caused no detectable renal injury at the dose employed. Previously described renal epithelial papillomas were identified, and were not influenced by altering the renal tissue kinetics of the drug. We conclude that no ‘protection’ procedure is necessary for the kidney when the streptozotocin model of diabetes is employed. In this regard streptozotocin may have greater utility than allo

ISSN:1420-4096    

DOI:10.1159/000172927

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

Whole kidney and single nephron function was compared in dogs during a stepwise lowering of renal perfusion pressure (PP) induced by aortic clamping (C) or hemorrhagic hypotension (HH). In C, renal vascular resistance (RVR) decreased with decreasing PP, the decrease being due to a drop in afferent resistance (RA) only. HH was associated with a rise in RVR due in the first phase mainly to an increase in RE, later to both RA and RE. There was a decrease in total kidney blood flow (RBF), glomerular filtration rate (GFR), glomerular and peritubular capillary pressure, and proximal tubular pressure. In C, RBF and GFR showed no significant difference at PPs 17 and 13 kPa. However, single nephron pressures were slightly but significantly lowered. In both groups, glomerular capillary hydraulic pressure (GCP) was significantly higher when calculated as SFP + πA (stop flow pressure + systemic arterial plasma oncotic pressure) than when measured directly by puncturing glomerular capillaries after ablation of a small layer of superficial cortex. This difference disappeared at PP 8 kPa. Ultrafiltration coefficient (Kf) seemed to increase with decreasing PP

ISSN:1420-4096    

DOI:10.1159/000172928

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

The role of kinins in the hypertensive response to acute renal artery constriction (RAC) was examined in the dog. RAC resulted in an increase in systemic arterial pressure (SAP) from 144 ± 6 to 155 ± 4 mm HG (p < 0.05). Simultaneously, arterial plasma bradykinin decreased from 2.3 ± 0.2 to 1.4 ± 0.1 ng/ml (p 0.05). At the same time urinary kallikrein decreased from 55 ± 6 to 33 + 4 milliesterase units (mEU)&slash;min (p < 0.05), while urinary kinin decreased from 3.2 + 0.4 to 1.9 + 0.3 ng/min (p < 0.05). There was a significant correlation between the decrease in arterial bradykinin and the rise in SAP induced by RAC (p < 0.01). Administration of the dipeptidyl hydrolase inhibitor SQ20881 during RAC reduced angiotensin-converting enzyme levels from 578 + 86 to 10 + 0.0 mU/ml (p < 0.005). There was an associated increase in arterial bradykinin (1.4 + 0.1 to 5.8 ± 0.8 ng/ml, p < 0.001), renal venous bradykinin (2.0 + 0.4 to 5.7 ± 0.5 ng/ml, p < 0.005), and urinary kinin (1.9 ± 0.3 to 5.0 ± 0.7 ng/min, p 0.05). These results suggest that (1) decreases in circulating BK may potentiate the vasoconstrictor effect of angiotensin II and contribute to the hypertension induced by RAC, and (2) urinary kallikrein is an unreliable marker of changes in plasma bradykinin in this model of hy

ISSN:1420-4096    

DOI:10.1159/000172929

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

Previous studies from this laboratory have demonstrated a phosphaturic response to hydrocortisone. The present micropuncture studies were undertaken to localize this glucocorticoid-induced effect along the nephron. Adult female Sprague-Dawley rats were used and parathyroidectomized 3 h before the micropuncture. The animals were infused with modified Ringer solution (either without or with phosphate). Hydrocortisone increased both the end-proximal transtubular concentration gradient of inorganic phosphate, (TF&slash;P)Pi, and the fractional delivery of Pi at the end of the proximal convolution significantly. The absolute reabsorption of Pi decreased from 95.1 ± 29.5 (mean ± SD) to 59.7 ± 28.2 pmol/min (p < 0.005) and the absolute reabsorption of Pi/single nephron glomerular filtration rate from 2.34 ± 0.59 to 1.35 ± 0.54 pmol/nl (p < 0.001) during Pi-Ringer infusion. It is concluded that the glucocorticoid-induced phosphaturia is primarily a result of the inhibition of the reabsorption of Pi in the proximal tu

ISSN:1420-4096    

DOI:10.1159/000172930

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

N-Acetyl-β-D-glucosaminidase (NAG) activities in urine, kidney, and plasma were compared in an age-matched group of male and female ds mice. In males, the NAG activity in the kidney was significantly higher (p < 0.001), and the urinary NAG activity (unit/g creatinine) was 8-fold higher than those for females, while plasma NAG levels were significantly lower (p < 0.001). These findings indicate that when using urinary NAG activity to detect drug nephrotoxicity in mice, the different basal levels between males and females should be considered before drug administration

ISSN:1420-4096    

DOI:10.1159/000172931

出版商:S. Karger AG    

年代:1984

数据来源: Karger