AJP - Renal Physiology, Vol 250, Issue 3 400-F406, Copyright © 1986 by American Physiological Society
Effect of amiloride on urinary and renal kallikrein in the rat
H. R. Croxatto, J. Corthorn, J. Roblero, P. Villalon and F. Perez
A single intraperitoneal injection of amiloride in the range of 2.7, 5.4,
10.9, and 21 mumol/100 g body wt in female adult rats produced, in the two
successive periods of 4 h following its administration, a significant
decrease in the urinary excretory rate of kallikrein. Amiloride, 10.9
mumol/100 g body wt, which significantly reduced active kallikrein, also
decreased, but less significantly, the trypsin-activated kallikrein in the
urine. The fall in the excretory rate of kallikrein cannot be explained by
its enzymatic inhibition by amiloride, since the inhibition was only
present at higher concentrations. In hyperhydrated rats amiloride did not
change the kallikrein excretory rate in the urine collected within 4 h
after the injection. Rats simultaneously injected with 7.6 mumol/100 g body
wt furosemide and 10.9 mumol/100 g body wt amiloride excreted levels of
kallikrein similar to those found in rats injected with furosemide alone.
The kidneys of rats removed after 4 h of administration of 10.9 mumol/100 g
body wt amiloride showed a significant lowering of the kallikrein activity
compared with the respective controls. The decrease of renal kallikrein
tended to be similarly pronounced in those rats that received amiloride and
furosemide simultaneously. These results confirm the depressive effect of
amiloride on kallikrein excretion, which may be explained by an inhibitory
action on kallikrein release, activation, and synthesis by the renal cells.
