The natriuretic effect of an acute peroral load of potassium chloride after inhibition of potassium secretion with amiloride or lithium.
The ability of the kidneys to excrete potassium after an acute peroral potassium load was studied in rats in which the kidney function was influenced by administration of amiloride or lithium for one month. Water, potassium chloride, or sodium chloride solutions were given by gastric tube immediately before a 2-hour clearance period. The results showed that a load of potassium given by gastric tube leads to an increase of potassium excretion in rats given either no treatment, amiloride, or lithium but the increase was about 50% lower in the lithium group. KCl administration provoked a considerable increase of sodium clearance (CNa) compared with the increase of CNa in the control group. The exaggerated natriuresis was apparently specific for potassium, since a peroral load of sodium chloride led to a more modest increase of CNa, an increase which was significant in control rats only. The increase of CNa in rats given a peroral load of potassium could not be explained by an increase of the proximal tubular fluid output, since the latter as measured by lithium clearance (CLi) remained unaltered. Since CNa/CLi rose considerably, the effect could be ascribed to an inhibition of the fractional distal sodium reabsorption.
D000284:Administration, Oral; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D004347:Drug Interactions; D008094:Lithium / Q000494:pharmacology; D008297:Male; D009318:Natriuresis / Q000187:drug effects*; D011189:Potassium Chloride / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012965:Sodium Chloride / Q000494:pharmacology
D012965:Sodium Chloride; D011189:Potassium Chloride; D000584:Amiloride; D008094:Lithium