Interdependence of Na-excretion, plasma electrolytes, plasma volume and renal Na-K-ATPase-activity in hypertensive rats.
Hypertensive Goldblatt-rats have higher than normal Na-appetite and an enhanced Na-output. They have normal plasma Na- and K-concentration and kidney weight but a significantly reduced plasma volume. The amount of renal membrane protein and the renal Na-K-ATPase-activity of hypertensive rats was found to be significantly below that of controls. In order to evaluate the role of Na-appetite, Na-excretion rate and renal Na-K-ATPase-activity in the electrolyte balance, Goldblatt-rats with a stable hypertension and control animals were put for 8 days on a Na-free diet. Na-excretion rate of control rats reached a minimum (13 muEq/100 g x 24 hr) within 5 days and was maintained on this level up to the end of the experiment. Na-free diet did not alter either the kidney weight or the amount of membrane protein of the animals. However, in salt-free fed control rats total renal Na-K-ATPase-activity was found elevated by about 10% as compared to animals maintained on normal diet. Goldblatt-rats continuously excreted significantly higher amounts of Na (35 muEq/100 g x 24 hr), had sharply reduced plasma volume and plasma Na- concentration. The renal Na-K-ATPase-activity should no adaptation in gold blatt-rats. In all animals studied the rate of Na-excretion showed a close indirect correlation with the renal Na-K-ATPase-activity. It is concluded, that Goldblatt-rats depend on dietary Na to a higher extent than controls because of their reduced capacity to retain Na. The increased Na-appetite of hypertensive rats is a factor secondary to Na-loss.
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D004195:Disease Models, Animal; D004789:Enzyme Activation; D006400:Hematocrit; D006977:Hypertension, Renal / Q000378:metabolism*; D007668:Kidney / Q000201:enzymology*; D008565:Membrane Proteins / Q000378:metabolism; D009929:Organ Size; D010953:Plasma Volume; D011188:Potassium / Q000097:blood* / Q000494:pharmacology; D051381:Rats; D012964:Sodium / Q000378:metabolism* / Q000494:pharmacology / Q000652:urine
D008565:Membrane Proteins; D012964:Sodium; D000251:Adenosine Triphosphatases; D011188:Potassium