摘要:

After restoring plasma volume to conscious levels, glomerular pressures and flows governing single nephron glomerular filtration rate (SNGFR) were measured in Munich-Wistar rats possessing surface glomeruli accessible to micropuncture. Although the mean glomerular transcapillary hydraulic pressure difference in these euvolemic rats was similar to that observed in hydropenic animals, initial glomerular plasma flow rate and SNGFR were at least 50% higher than in hydropenic rats. Nevertheless, filtration pressure equilibrium was generally achieved in euvolemic rats, as in hydropenic rats. Afferent and efferent arteriolar resistances were found to be lower in euvolemic than hydropenic rats, suggesting more potent vasoconstrictor forces in the latter group.

ISSN:1420-4096    

DOI:10.1159/000172653

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

The effects of intrarenal arterial (6.5 µg/kg/min) and intravenous (33 µg/kg/min) administration of propranolol on sodium excretion and renal hemodynamics were studied in anesthetized dogs. Heart rate, plasma renin activity and renal plasma flow were reduced by propranolol administered by either route. Blood pressure was reduced following intravenous infusion. Urinary sodium excretion was reduced by propranolol. This reduction was inversely correlated with the basal state of sodium excretion, and was also correlated with the reduction of glomerular filtration rate, effective renal plasma flow and blood pressure. We suggest that the antinatriuretic effect of propranolol is due to the reduction of glomerular filtration rate and of hydrostatic pressure in the proximal tubule, although additional factor(s) are not completely ruled ou

ISSN:1420-4096    

DOI:10.1159/000172654

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

We studied the effect of varying the sodium concentration on the tissue swelling and metabolism of renal cortical slices from control and acidotic rats. Lowering the sodium concentration in the incubation medium caused increased tissue swelling and depressed glutamine uptake, ammoniagenesis and gluconeogenesis in slices from both control and acidotic rats.

ISSN:1420-4096    

DOI:10.1159/000172655

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

Phosphoenolpyruvate carboxykinase (PEPCK) in the renal cortex shows the expected increase in activity but oxal acetate decarboxylase and malic enzyme, two other enzymes capable of providing precursors for use in the total oxidation of glutamine by the kidney, showed no change in their activity as a result of metabolic acidosis in rats. 3-Mercaptopicolinic acid, a substance which inhibits PEPCK, caused a 23% decrease in the oxidation of glutamine to CO2 by kidney cortical slices in vitro. 3-Mercaptopicolinic acid in vivo had anomalous effects on gluconeogenesis but consistently inhibited ammoniagenesis by kidneys of normal as well as acidotic rats.

ISSN:1420-4096    

DOI:10.1159/000172656

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

The effects of indomethacin on hemodynamic and excretory alterations produced by acute ureteral obstruction were investigated in anesthetized dogs by means of radiolabeled microspheres and clearance techniques. Renal blood flow in untreated animals increased by 40 ± 12% with acute ureteral pressure elevation in comparison to the contralateral unobstructed kidney. This increase was only 7 ± 3% (p < 0.01) in indomethacin-treated animals. Likewise untreated animals exhibited a redistribution of blood flow from superficial to deeper cortex while indomethacin-treated animals showed no redistribution (p < 0.025). However, indomethacin treatment did not alter changes in glomrular filtration rate or electrolyte excretion of acute obstruction. These results suggest that prostaglandins or closely related compounds are involved in the hemodynamic changes of acute obstruction, but that they do not play an important role in the determination of glomerular filtration rate or electrolyte excretio

ISSN:1420-4096    

DOI:10.1159/000172657

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

Polyethylene-(1, 2-14C)-glycol is a reliable probe of the extracellular space in renal cortex slices. The PEG distribution volume is similar to that measured with inulin (24–25% of wet slice weight at 30 min). Comparable values were found using PEG and inulin in slices from newborn, 4-week-old and adult animals. Contamination of PEG with low molecular polymers did not occur, in contrast with our experience with stored inuli

ISSN:1420-4096    

DOI:10.1159/000172658

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

The effect of NaHCO3 infusion on phosphate reabsorption by the proximal convoluted tubule was studied in acute and chronic PTX rats. Either hypertonic NaHCO3 or NaCl was infused intravenously. Proximal fluid and phosphate reabsorption were measured with 3H-inulin and 32PO4, respectively. In acute PTX rats, the fraction of filtered 32PO4 remaining in the proximal lumen was 5.9% during NaCl infusion and 23% during NaHCO3 infusion (p < 0.001). In the chronic PTX rats, the fraction of filtered 32PO4 remaining in the proximal lumen was 24% during NaCl infusion and 38% during NaHCO2 infusion (p < 0.001). Phosphate reabsorption per unit GFR was reduced by NaHCO2infusion in both acute and chronic PTX rats. A linear relationship was found between tubular fluid total CO2 and the fraction of 32PO4 remaining in the tubular lumen. The findings indicate that NaHCO3 infusion inhibits phosphate reabsorption in the proximal convoluted tubule by a mechanism not dependent on PTH or volume expansion, but apparently correlated with intraluminal CO2.

ISSN:1420-4096    

DOI:10.1159/000172659

出版商:S. Karger AG    

年代:1978

数据来源: Karger