AJP - Renal Physiology, Vol 248, Issue 1 104-F112, Copyright © 1985 by American Physiological Society
Effects of dietary potassium depletion and mineralocorticoid excess on renal Cl-conservation in the dog
H. N. Hulter, J. H. Licht and A. Sebastian
Preexisting dietary K+ depletion (KD) in dogs exaggerates the renal acid
excretory response to mineralocorticoid hormone (MCH) and attenuates the
renal Cl- reabsorptive response without altering the Na+ reabsorptive
response. The exaggerated acid excretory response has been postulated to be
an electrophysiological consequence of a defect in renal Cl- reabsorption
caused by KD. To investigate the specific effects of KD on renal Cl-
transport in dogs, we assessed renal Cl- conservation during dietary Cl-
restriction in KD adrenalectomized dogs maintained on physiological
replacement doses of MCH. After a 16-day period of dietary K+ restriction
and physiological MCH replacement, reduction of dietary NaCl from 5.0 to
0.25 mmol X kg-1 X 24 h-1 was attended by reduction in urinary Cl-
excretion to values less than intake and to significantly lower values than
in K+ -replete controls. In a subsequent experimental period of continued
Cl- restriction and administration of DOC (15 mg/24 h, i.m.), urinary Cl-
excretion decreased further in both groups to stable values, but the values
were significantly greater in KD (2.7 +/- 0.4 vs. 1.1 +/- 0.1 meq/24 h, P
less than 0.05) and the cumulative retention of urinary Cl- was
significantly less (10.3 +/- 1.4 vs. 29.5 +/- 6.7 meq, P less than 0.05).
These findings demonstrate that preexisting dietary KD accelerates chronic
renal Cl- conservation in response to dietary Cl- restriction under
conditions in which MCH supply is normal and fixed but that it impairs
maximal renal Cl- -conserving ability in response to MCH excess.
