AJP - Renal Physiology, Vol 260, Issue 2 170-F176, Copyright © 1991 by American Physiological Society
Stimulation of renin release by hyperkalemia in the nonfiltering kidney
H. B. Lin, D. B. Young and M. J. Smith Jr
Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson 39216-4505.
This study was designed to analyze the acute effects of hyperkalemia on
renin release in the normal filtering kidney and the nonfiltering kidney.
Plasma K was increased by acute intravenous KCl infusion. In the normal
filtering kidney experiment plasma K was 5.7 vs. 3.5 meq/l. Hyperkalemia
resulted in a 45% increase in renal blood flow (RBF) and a 35% increase in
glomerular filtration rate (GFR) at the 120-mmHg pressure level. Renin
release was significantly greater in the hyperkalemic group than in the
control group (P less than 0.01) with the greatest effect over the lower
pressure range. In the nonfiltering kidney experiment plasma K was 6.09 vs.
3.5 meq/l. RBF was 33% greater in the hyperkalemic than in the normokalemic
group at the 130-mmHg pressure level. Renin release was also greater in the
hyperkalemic group than in the normokalemic group (P less than 0.01).
However, unlike the normal filtering kidney experiments, in the
nonfiltering kidneys the difference in renin release was most prominent at
the highest level of renal perfusion pressure. These experiments
demonstrate that acute hyperkalemia can cause renal vasodilation and
stimulate renin release in both filtering and nonfiltering kidney
preparations and that potassium may affect renin release both through a
direct effect on the juxtaglomerular cells and indirectly by affecting
delivery of fluid and/or NaCl to the macula densa.
