AJP - Renal Physiology, Vol 242, Issue 5 463-F469, Copyright © 1982 by American Physiological Society
Effects of acute potassium infusions with salts other than chloride on plasma renin activity
K. A. Kirchner and R. Mueller
To evaluate the contribution of chloride to the suppression of plasma renin
activity (PRA) by KCl, PRA was measured before and after venous infusions
of KCl, KHCO3, KNO3, and KC2H3O2 in dietary NaCl-restricted rats. In
contrast to controls, PRA decreased (P less than 0.02) after infusion of
each potassium salt [KCl from 55.3 +/- 6.4 to 27.0 +/- 6.4 ng.ml-1.h-1
(mean +/- SE); KC2H3O2 from 39.3 +/- 4.0 to 20.6 +/- 4.0; KHCO3 from 64.4
+/- 6.2 to 47.2 +/- 6.2; KNO3 from 40.0 +/- 4.0 to 18.6 +/- 4.0]. Arterial
pressure, plasma volume, inulin clearance, serum sodium concentration, and
net sodium balance were not different between control and potassium-infused
groups. Potassium loading did not increase absolute or fractional sodium
excretion. PRA failed to decrease in animals given an equal volume of
NaNO3. Furosemide prevented the fall in PRA associated with potassium
loading despite replacement of urinary losses. These results suggest that
the decrease in PRA observed during potassium loading occurs through the
macula densa mechanism but is not dependent on concomitant chloride
administration. As furosemide prevents the fall in PRA, macula densa
chloride transport may be necessary for potassium to exert this effect.
