High protein intake accelerates the maturation of Na,K-ATPase in rat renal tubules.
We have examined the effect of a high protein intake on renal maturation by studying the Na,K-ATPase activity in proximal convoluted tubules (PCT) and medullary thick ascending limb of Henle (TAL) in kidneys from 16- to 24-day-old rats. The rats received an isocaloric diet containing 21% (normal protein, NP) and 50% (high protein, HP) protein from 16 days of age. HP diet significantly increased the nephron filtration rate after 2 days. There was a proportionate increase in proximal tubular reabsorption. HP diet significantly increased Na,K-ATPase in both PCT and TAL after 4 days, but not after 2 days. Although HP diet caused a similar increase in Na delivery to PCT and TAL, the increase in Na,K-ATPase activity after 8 days was more pronounced in TAL than in PCT. To determine whether stimulation of Na,K-ATPase required the presence of adrenal corticoid hormones, rats adrenalectomized at 16 days of age were studied. HP diet significantly increased Na,K-ATPase in both PCT and TAL from adrenalectomized rats. To determine whether stimulation of Na,K-ATPase in PCT was mediated by increased Na entry via the amiloride-sensitive Na/H exchanger, rats were treated with amiloride via an osmotic minipump from 16 to 20 days of age. Amiloride treatment significantly retarded the normal increase of Na,K-ATPase in NP rats but had no effect on ouabain-insensitive ATPase. HP diet significantly increased PCT Na,K-ATPase, in spite of chronic amiloride treatment.


CONCLUSIONS
HP intake accelerates maturation of Na,K-ATPase in PCT and TAL regardless of the presence of adrenal corticoid hormone.(ABSTRACT TRUNCATED AT 250 WORDS)
Jakobsson
B
B
Department of Pediatrics, Huddinge Hospital, Sweden.
Aperia
A
A
D000315:Adrenalectomy; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D001835:Body Weight / Q000187:drug effects; D004044:Dietary Proteins / Q000494:pharmacology*; D005919:Glomerular Filtration Rate / Q000187:drug effects; D007668:Kidney / Q000033:anatomy & histology; D007684:Kidney Tubules / Q000201:enzymology*; D008297:Male; D009399:Nephrons / Q000187:drug effects; D009929:Organ Size / Q000187:drug effects; D051381:Rats; D011919:Rats, Inbred Strains; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
D004044:Dietary Proteins; D000584:Amiloride; D000254:Sodium-Potassium-Exchanging ATPase