EFFECT OF ALDOSTERONE ON RENAL Na,K-ACTIVATED ADENOSINE-TRIPHOSPHATASE ACTIVITY IN NON-ADRENALECTOMIZED RATS

Abstract

It has been reported that the activity of Na, K-activated adenosinetriphosphatase (Na,K-ATPase) in the kidney is reduced by adrenalectomy and that the activity is restored by administration of aldosterone (1, 2). However, with the adrenalectomized rats, the restoration of the enzyme by aldosterone has been shown to take much longer time (i.e. 6-24 hr) as compared with the time (1-2 hr) for the maximal effect of aldosterone on the sodium reabsorption (3). We attempted to determine whether or not aldosterone stimulates Na,K-ATPase in correlation with the enhancement of Na reabsorption in non-adrenalec tomized rats.Male Wistar rats weighing 170-250 g were used. Each animal was given water (3 ml p.o.) and pitressin tannate in oil (0.5 U i.m), and then anesthetized 1 hr later with pen tobarbital sodium (30 mg/kg i.p.). Administration of 5 % mannitol through the femoral vein was started at a rate of 0.1 ml/ruin and continued during the experiment. After a 30 min equilibration period, one 30-min urine collection was made and then aldosterone (10 /tg per animal) was given i.v. to animals of the experimental group. The control animals were infused with 5 % mannitol through the experiment. The bladder was catheterized and sodium and potassium in the urine were determined by flame photometry (Hitachi 205), and the chloride content by a chloridemeter (Hiranuma, Chloride Counter CL-3). To determine the activities of Mg and Na,K-ATPase, animals were sacrificed and the kidney

Ethacrynic Acid-Sensitive and ATP-Dependent Cl- Transport in the Rat Kidney

“…Since Cl -ATPase in the brain is supposed to transport C1 in an ATP dependent manner through a process not re lated to Na+,K+-ATPase or Na+ /K+ /Cl cotransport (4), the activities of Cl ATPase and ATP-dependent Cl uptake in cortical and medullary microsomes were assayed in the presence of Na+,K+-ATPase and/or Na+/K+ /CI_ cotransport inhibitors, 1 mM ouabain and/or 0.1 mM furosemide (see legend of Table 2). The activity of Na+,K+-ATPase, known to be a plasma membrane-marker en zyme with a characteristic regional distribution in the kidney (12,13), showed a distribution profile similar to that reported: outer medulla > cortex > inner medulla. The activities of both C1--ATPase and ATP-dependent Cl uptake were high in the cortex as compared with those in the medullary regions.…”