Regulation of the renal Na:K pump: role of progesterone.
In male Sprague-Dawley rats, the effects of exogenous high physiologic levels of progesterone simulating those observed in pregnancy (5 mg/day) on Na:K pump activity (picomoles per millimeter per hour) in microdissected nephron segments were evaluated. In adrenal-intact rats, progesterone led to a generalized decrease in Na:K pump activity in proximal convoluted tubule from 2,524 +/- 61 to 741 +/- 41 (71% reduction; P < 0.01), medullary thick ascending limb (MAL) from 4,793 +/- 217 to 2,000 +/- 133 (59% reduction; P < 0.01), and cortical collecting tubule (CCT) from 1,141 +/- 69 to 591 +/- 133 (49% reduction; P < 0.01). This effect was similar in magnitude to the decline observed with adrenalectomy alone. In adrenalectomized rats, progesterone had no further inhibitory effect on the pump in MAL (2,172 +/- 66 versus 2,312 +/- 71) or CCT (493 +/- 58 versus 530 +/- 31) but led to a modest decline in Na:K pump activity in the proximal convoluted tubule (from 1,136 +/- 88 to 528 +/- 31; P < 0.01). In adrenal-intact rats, a high K diet for 7 days led to an increase in CCT Na:K pump activity from 1,141 +/- 69 on a normal potassium diet to 2,224 +/- 33 pmol/mm per h (P < 0.001). Progesterone treatment reduced basal Na:K pump activity in CCT, and concurrent progesterone treatment blunted the stimulatory effect of K adaptation on the pump (973 +/- 68 pmol/mm per h; P < 0.001 versus untreated).(ABSTRACT TRUNCATED AT 250 WORDS)
Department of Medicine, Northwestern University Medical School, Chicago, IL.
S K
SK
Mujais
N A
NA
Nora
Y
Y
Chen
D000311:Adrenal Glands / Q000502:physiology; D000315:Adrenalectomy; D000450:Aldosterone / Q000494:pharmacology; D000818:Animals; D007668:Kidney / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D011374:Progesterone / Q000378:metabolism* / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D000254:Sodium-Potassium-Exchanging ATPase / Q000187:drug effects / Q000502:physiology*
D000450:Aldosterone; D011374:Progesterone; D000254:Sodium-Potassium-Exchanging ATPase