摘要:

This study evaluates the direct effects of verapamil (5 µg/kg/min) or nifedipine (0.32 µg/kg/min) when infused into one renal artery for 2 h. The role of calcium in the systemic and renal vascular effects of angiotensin II (1 µg/i.v.bolus) was examined in each period.Renal blood flow was increased 11% by verapamil and 29% by nifedipine. Unlike other vasodilators, these drugs markedly increased GFR (by 75% with verapamil and 50% with nifedipine), and both caused a profound natriuresis, which outlasted the renal hemodynamic changes. Further, they abolished the renal vascular responses to angiotensin II. These major direct effects on renal function and hemodynamics suggest that: (a) calcium blockers may affect the determinants of GFR differently from other vasodilators, and (b) they may interfere with proximal tubular Na+ transpo

ISSN:1420-4096    

DOI:10.1159/000172955

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

The direct action of angiotensin II on renal glomeruli was quantified by measuring extracellular space in isolated, decapsulated rat glomeruli using 14C-inulin. The glomerular inulin space significantly decreased when treated with 0.1 nM to 1 µM of angiotensin II. The decrease was dose-dependent and blocked by 1-Sar, 8-Ile angiotensin II. Since the glomerular intracapillary space seems to occupy the majority of the extracellular (inulin) space in decapsulated glomeruli, these results suggest that angiotensin II decreases the glomerular intracapillary volume. This action of angiotensin II may lead to a reduction in glomerular filtering surface area, and thus, in the ultrafiltration coefficient

ISSN:1420-4096    

DOI:10.1159/000172956

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

The mouse strain C57BL is characterized by a high urinary fractional excretion of taurine. Hypertaurinuric [tau(-)] C57BL mice and three normal taurine ‘excretors’ [tau(+)] – Swiss, A/J, and C3H – were compared. Clearance experiments showed that fractional excretion of taurine was 4-8 times higher in C57BL relative to the other strains. Transport studies performed in brush border membrane vesicles, isolated from C57BL and C3H mouse renal cortex, showed that D-glucose uptake was similar in both strains while the taurine uptake appeared to be faster in tau(+) than in tau(-) mice. This difference was observed only in the presence of an inwardly directed NaCl gradient. The comparison of kinetic parameters showed a significant difference of apparent Km values: 90.8 ± 11.4 µM in tau(+) mice vs. 129.5 ± 17.1 µM in tau(-) mice. Jmax were not significantly different in both strains. These observations suggest a lower affinity of the taurine brush border membrane carrier in the hypertaurinuric strain as compared to the normotaurinuric mice. It is concluded that, in addition to a possible alteration of peritubular taurine efflux described by Rozen et al. (1983), a defect of taurine transport at the luminal membrane cannot be excluded and could account for the hypertaurinuria of the

ISSN:1420-4096    

DOI:10.1159/000172957

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

In order to decide whether foot process abnormalities in nephrotic states are the cause or the consequence of proteinuria, the polycation protamine has been applied to isolated perfused rat kidneys and functional parameters and morphology have been compared. With 110 μg/ml protamine the albumin clearance ratio increased from 2.0 + 0.7 × 10-3 in controls to 14.8 + 6.9 × 10-3 10-20 min after application and even to 98.0 + 30.8 × 10-3 after 50-80 min. Micropuncture samples collected from early proximal tubules with pressure control were used to calculate the sieving coefficient which correlated with albumin clearance ratios (controls: 1.8 +1.0 × 10-3; after 10-20min: 11.8 ± 6.4 × 10-3; after 50-80 min: 52.0 + 8.5 × 10-3). Glomerular filtration rate decreased in the early beginning from 1.1 ± 0.2 ml x min-1 ×g-1 kidney to 0.7+ 0.2 ml × min-1 ×g-1 kidney, but remained constant throughout the whole experiment. Despite the markedly increased albuminuria there were no changes in glomerular foot process morphology with the protamin

ISSN:1420-4096    

DOI:10.1159/000172958

出版商:S. Karger AG    

年代:1984

数据来源: Karger

ISSN:1420-4096    

DOI:10.1159/000172959

出版商:S. Karger AG    

年代:1984

数据来源: Karger

ISSN:1420-4096    

DOI:10.1159/000172960

出版商:S. Karger AG    

年代:1984

数据来源: Karger

ISSN:1420-4096    

DOI:10.1159/000172961

出版商:S. Karger AG    

年代:1984

数据来源: Karger

ISSN:1420-4096    

DOI:10.1159/000172954

出版商:S. Karger AG    

年代:1984

数据来源: Karger