Na-K-ATPase along rat nephron after subtotal nephrectomy: effect of enalapril.
Tubular overwork is thought to be a promoter of the tubular hypertrophy and renal failure that occur in response to renal mass reduction. Because Na-K-adenosinetriphosphatase (Na-K-ATPase) is an index of tubular work, we evaluated the effects of subtotal nephrectomy and of enalapril therapy, which delays the evolution of renal lesions, on tubular hypertrophy and Na-K-ATPase activity along the rat nephron. Within 6 wk, 70% reduction of renal mass engendered hypertrophy of the proximal convoluted tubule (PCT), thick ascending limb (TAL), and collecting duct (CD), as well as parallel increments in Na-K-ATPase activity per millimeter tubule length (Na-K-ATPase activity per unit surface area was not modified by subtotal nephrectomy). Chronic enalapril therapy prevented part of the hypertrophy (but not Na-K-ATPase stimulation) of the PCT and the whole stimulation of Na-K-ATPase (but not hypertrophy) in the CD, whereas it had no effect on the TAL. Enalapril effect on Na-K-ATPase in CD might result from reduced bradykinin metabolism, as the reduction in urinary excretion of bradykinin observed in subtotally nephrectomized rats was prevented by enalapril therapy.
Terzi
F
F
Institut National de la Santé et de la Recherche Médicale (INSERM) U 426, Faculté Xavier Bichat, Paris, France.
Cheval
L
L
Barlet-Bas
C
C
Younes-Ibrahim
M
M
Buffin-Meyer
B
B
Burtin
M
M
Beaufils
H
H
Marsy
S
S
Girolami
J P
JP
Kleinknecht
C
C
Doucet
A
A
D000450:Aldosterone / Q000097:blood; D000818:Animals; D001920:Bradykinin / Q000652:urine; D004656:Enalapril / Q000494:pharmacology*; D006984:Hypertrophy / Q000517:prevention & control; D007684:Kidney Tubules / Q000187:drug effects / Q000201:enzymology / Q000473:pathology; D008297:Male; D009392:Nephrectomy; D009399:Nephrons / Q000201:enzymology*; D051381:Rats; D017208:Rats, Wistar; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
D000450:Aldosterone; D004656:Enalapril; D000254:Sodium-Potassium-Exchanging ATPase; D001920:Bradykinin