摘要:

Clearance methods, allowing for repeated use in the same animals, were applied in a cross-sectional study to establish the normal increase in renal function in rats. It was shown that the glomerular filtration rate (GFR) and the effective renal plasma flow (ERPF) per gram of kidney was low in the 4-week-old rats. Levels comparable to those of adult rats were reached at an age of about 7 weeks. From that age on the GFR and the ERPF, as well as kidney weight, increased at a lower rate than did the body weight. The present findings, obtained by these rather simple techniques are, in general, concurrent with data from the literature on the development and maturation of renal function in rats.

ISSN:1420-4096    

DOI:10.1159/000172875

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

Infusion of substance P into the renal artery was previously shown to cause a significant natriuresis which was associated with increased kallikrein excretion. Since the renal kinin and prostaglandin (PG) systems may be interrelated, the present study was performed to investigate the effects of substance P on renal function and its potential interaction with the renal PG system in the conscious rat. 24 female Sprague-Dawley rats were infused intravenously with substance P (1 ng · min-1 · kg-1 body weight) and the body weight was kept constant by an intravenous infusion of 0.45% saline. Substance P had no effects on arterial blood pressure, glomerular filtration rate (GFR) and 125I-hippuran clearance in the absence or presence of indomethacin (INDO). Basal UPGE2 V was unaltered by substance P infusion but was suppressed by INDO before and during substance P by 80 and 88%, respectively. Substance P raised urinary flow rate (V) by 105%, CH2O by 96%, UNaV by 378%, UKV by 48% and UPO4V by 147% (p < 0.001). Although INDO significantly suppressed V, CH2O, and UNaV during all collection periods, it did not affect absolute UPO4V and UKV and the relative rise in V, CH2O, and UNaV induced by substance P. Thus, the diuretic and natriuretic effects of substance P are not mediated by renal PG, but are partially blunted by INDO through increased distal absorption of sodium and water, INDO has no effect on substance P-induced alterations in proximal tubular functio

ISSN:1420-4096    

DOI:10.1159/000172876

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

The distribution of [14 C]-5 5-dimethyl-2 4-oxazolidinedione ([14 C]-DMO) was measured in intact rat renal cortex using 22Na+ to estimate extracellular fluid volume. Results of two different methods to obtain tissue were compared, a cortical slice technique and a whole kidney frozen technique. In normal animals with a mean blood pH of 7.41 + 0.006 (SEM) the cortical slice method measured an intracellular pH of 6.97 + 0.03 (SEM). Corrections are described which can be used to compensate for varying volumes of tubular fluid in the slice and for differing concentrations of intracellular sodium. Using reasonable estimates for tubular fluid volume and intracellular sodium these corrections increase the value of intracellular pH to about 7.20. The results of the study indicate that the cortical slice [14C]-DMO method provides a satisfactory technique to obtain baseline values for intracellular pH in intact renal cortex, which can be used to detect changes in intracellular pH produced by experimental manipulations.

ISSN:1420-4096    

DOI:10.1159/000172877

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

Intracellular pH (pHI) of intact rat renal cortex was estimated using [14C]-5,5-dimethyl-2,4-oxazolidinedione and 22Na+ under conditions of metabolic acidosis and alkalosis, potassium depletion and carbonic anhydrase inhibition. In metabolic acidosis and alkolosis, pHI and bicarbonate concentration changed in the same direction as occurred in plasma. In potassium depletion, systemic acid-base balance was unaltered but a marked intracellular acidosis developed. Carbonic anhydrase inhibition with acetazolamide was associated with an extracellular respiratory acidosis and a rise in intracellular bicarbonate concentration. Another carbonic anhydrase inhibitor, benzolamide, caused no change in systemic acid-base state but produced a decrease in intracellular bicarbonate concentration. When appropriate corrections were made for predicted change in tubular fluid bicarbonate and for intracellular sodium, modification in the absolute values of the above changes occurred but the directions of the changes in pHI and bicarbonate concentration were unaltered.

ISSN:1420-4096    

DOI:10.1159/000172878

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

Head-up tilt is associated with rapid increases in total peripheral and renal resistance and falls in the urinary excretion of water and sodium. The influence of the acute oral administration of the converting enzyme inhibitor captopril (50 mg) on the consequences of 60° head-up tilt were assessed in 6 normal subjects on unrestricted sodium intake. Captopril did not modify the responses of arterial pressure and heart rate to tilt, although a significant decrease in supine mean arterial pressure was induced by captopril. In addition, the agent blunted by 50–60% all the changes in renal hemodynamics and urinary excretion of water and electrolytes except for that of the fractional excretion of sodium. Urinary kallikrein activity which markelly fell and plasma aldosterone concentration which increased during tilt before captopril were not affected after administration of the drug. These studies indicate that angiotensin might mediate at least in part the renal hemo-dynamic and functional responses to tilt in normal man and is the primary determinant of the aldosterone stimulating effect of ti

ISSN:1420-4096    

DOI:10.1159/000172879

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

The effect of hemorrhagic hypotension (HH) on local and total renal blood flow was studied in rats. Cortical blood flow, measured as H2 gas clearance, was determined before and during HH with a mean arterial blood pressure of 50 mm Hg. During the initial 10-5 min of bleeding renal cortical vascular resistance was unchanged, and total renal blood flow autoregulatory ability was abolished. Cortical vascular resistance thereafter increased steadily to twice the control level after 90 min of HH. At this time, retransfusion of the shed blood improved cortical blood flow due to increased arterial blood pressure, not to reduced cortical vascular resistance. In a second group, total and local renal blood flows were obtained from 125I-iodoantipyrine uptake rate after 2 h of HH with arterial blood pressure maintained at 50 mm Hg. Total renal blood flow was reduced to 20% of control with no change in blood flow distribution between outer and inner cortical or medullary zones. Both cortical blood flow and intrazonal local renal blood flow heterogeneity had increased at the end of the HH period. However, ischemic and extremely low flow sectors comprising cortex and outer medulla were observed only in 1 of the 10 kidneys studied with the 125I-iodoantipyrine technique. In only 1 of 8 animals studied with the H2 gas method were intermittent sudden changes in cortical blood flow observed during HH. Since hematocrit tended to fall during HH, these observations support the concept that local flow intermittence is predominately associated with high hematocrit shocks.

ISSN:1420-4096    

DOI:10.1159/000172880

出版商:S. Karger AG    

年代:1983

数据来源: Karger