摘要:

Measurements of renin concentration in nanolitre samples of efferent arteriolar (Re), renal venous (Rv) and arterial (Ra) plasma showed that Re equalled Rv and was significantly higher than Ra at low and moderate net secretion rate. Net addition of renin directly into the circulating blood from the juxtaglomerular apparatus was insignificant at low rates of renin secretion (Rv/Ra < 1.3). At higher secretion rates (Rv/Ra ≧ 1.3) at least 37% of net secretion was released directly into the blood (p < 0.05). The haematrocrit (Hct) of collected efferent arteriolar blood was artifactually increased (72.3%) above the value calculated from the arterial Hct (48%) and the filtration fraction of 0.2

ISSN:1420-4096    

DOI:10.1159/000172646

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

The effect of insulin was studied in a kidney in vitro preparation to examine if it had a direct interaction with the Na+K+-ATPase system. Cortical and medullary microsomes obtained from dog kidney were utilized for the ATPase assay. Addition of 0.4 µg/ml of the hormone significantly increased the activity with 4 mM Na+:10 mM K+ (n = 8, p < 0.05) and 140 mM Na+:4 mM K+ (n = 8, p < 0.005) from basal (no insulin) activity. On the other hand, 20.8 µg/ml of insulin was needed to significantly increase the activity when 100 mM Na+: 10 mM K+ were present (n = 8, p < 0.05). The identity of the enzyme stimulated was corroborated by adding ouabain (10–3 M) and insulin (4.0 µg/ml) to the preparation; the glycoside was able to block all the stimulation; no change in Mg2+-ATPase was observed in any experi

ISSN:1420-4096    

DOI:10.1159/000172647

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

Radiolabeled anti-glomerular basement membrane (AGBM) antibody was injected in rats and its distribution was studied in different glomerular populations by microdissection. It was compared with 15 µmmicrosphere distribution. AGBM antibody was not fully extracted in a single renal pass, precluding therefore its use as an indicator of intrarenal plasma flow. The amount of AGBM antibody fixed in juxtamedullary glomeruli was higher than in others. This result may be related to the larger capillary surface area in the former. In contrast, microspheres predominated in the superficial glomeruli. In addition to blood flow, rheologic factors probably lead to sphere accumulation in these glomeruli. Therefore, neither AGBM antibody nor microspheres accurately reflect glomerular blood flow distribution in the rat kidney

ISSN:1420-4096    

DOI:10.1159/000172648

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

The isolated rat kidney perfused with a cell-free perfusion medium produces urine with a solute concentration at or below that of the perfusate. Vasopressin (Pitressin®), arginine vasopressin, DDAVP or dibutyryl cyclic AMP increased urine osmolality to a maximum of 20% above that of perfusate. The increase in urinary solute concentration was similar to the increase in solute content in the inner medulla of the perfused kidney. Inhibition of prostaglandin synthesis with indomethacin or acetyl salicylate decreased free water clearance slightly but did not increase urinary osmolality in response to antidiuretic hormone (ADH). Nor did inclusion of urea in the perfusate enhance the maximal response to ADH. It is concluded that the concentrating ability of the isolated perfused kidney is not improved by inhibition of prostaglandin synthesis and is limited by an inability to increase medullary solute concentration in the presence of the high perfusion flow rates which characterize this preparation

ISSN:1420-4096    

DOI:10.1159/000172649

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

The glomerular filtration rate (GFR), effective renal plasma flow (ERPF), urine osmolality, urine flow rate, urea excretion, osmolar clearance, and free water reabsorption were measured in a group of 5 female dromedary camels in control conditions and also after 10 days dehydration in both early and mid-summer. There was a loss of 23% in mean body weight and a fall of 75% in GFR in severe dehydration, with a parallel reduction in ERPF and in urine flow rate. Urine osmolality reached a mean maximum of 1,466 mosm/kg in severe dehydration of mid-summer, the highest individual urine osmolality being 2,372 mosm/kg. Osmolar clearance, free water absorption and urinary urea excretion were lower in dehydration. Urea/inulin clearance ratio was significantly lower in dehydration (p < 0.001). Sodium excretion did not change in dehydration. Fractional reabsorption of urea was higher in dehydration, reaching a maximum value of 74% of the filtered load. The fall in urinary urea concentration was one of the factors contributing to the poor concentrating ability of the severely dehydrated camel kidney, probably caused by the fall in GFR and increase in tubular reabsorption of urea, rather than by protein deprivation.

ISSN:1420-4096    

DOI:10.1159/000172650

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

A kinetic analysis of the rate of active (oxygen-dependent) accumulation of p-aminohippurate (PAH) by rabbit renal cortical slices was performed to confirm the existence of multiple renal organic anion transport systems. The kinetic analysis demonstrated the presence of two active uptake modes for PAH in this slice system. Acetate increased the rate of the oxygen-requiring component of each mode of PAH uptake by increasing the apparent Vmax of transport. Additional PAH transport modes were not revealed by the addition of acetate. These results were consistent with the hypothesis that more than one active transport system participates in the transport of organic anions in the renal proximal tubule cell.

ISSN:1420-4096    

DOI:10.1159/000172651

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

A special cannula for direct intrarenal artery injections has been prepared from a 19-gauge Intracath®. This cannula (with its stylet) possesses a proper degree of flexibility in spite of its small caliber (o.d. 0.40 mm, i.d. 0.26 mm).The surgical procedure, which involves catheter insertion to one renal artery through the stump of the opposite renal artery, can be accomplished over a short period of time with essentially no blood loss This method affords an opportunity of studying the effect of various drugs directly injected into the isolated kidney in vivo. No changes in plasma renin concentration was observed in the animals after renal artery cannulation. This method enables chronic cannulation of the renal artery

ISSN:1420-4096    

DOI:10.1159/000172652

出版商:S. Karger AG    

年代:1978

数据来源: Karger