AJP - Renal Physiology, Vol 249, Issue 4 596-F602, Copyright © 1985 by American Physiological Society
Renin secretion and loop of Henle chloride reabsorption in the adrenalectomized rat
W. J. Welch, C. E. Ott, G. P. Guthrie Jr and T. A. Kotchen
Renin release is increased in the adrenalectomized rat and is not inhibited
by sodium chloride administration. The purpose of this study was to
determine whether increased renin release is related to impaired absorptive
chloride transport in the loop of Henle. Chloride transport in the loop was
measured before and after acute saline infusion in three groups of rats: 1)
saline-drinking adrenalectomized rats (Adx); 2) saline-drinking
dexamethasone-treated adrenalectomized rats (Dex); and 3) water-drinking
sham-operated controls. Unrelated to differences of arterial pressure,
glomerular filtration rate, or net sodium chloride balance, chloride
reabsorption in the loop of Henle of Adx [836 +/- 172 peq/min (SE)] was
less (P less than 0.01) than in controls (1,646 +/- 353) and Dex (1,377 +/-
318) before saline infusion. After saline infusion, chloride delivery to
the loop increased (P less than 0.05) in all three groups. However, loop
chloride reabsorption increased (P less than 0.01) only in controls and Dex
but not in Adx. Before saline infusion, plasma renin concentration (PRC) of
Adx (350 +/- 108 U/ml) was greater (P less than 0.01) than that in controls
(56 +/- 6) or Dex (108 +/- 36); sodium chloride infusion failed to inhibit
PRC in Adx, whereas PRC was suppressed (P less than 0.01) by saline in Dex
and controls. Thus stimulation of renin release in adrenalectomized animals
was associated with decreased absorptive chloride transport in the loop of
Henle. Dexamethasone normalized loop function and renin responsiveness to
sodium chloride.
