Journal of Applied Physiology, Vol 67, Issue 3 938-944, Copyright © 1989 by American Physiological Society
Effects of clonidine and dihydralazine on atrial natriuretic factor and cGMP in humans
M. Wehling, T. Muller, J. M. Heim, R. Lorenz, H. Witzgall, J. Weil and R. Gerzer
Department of Medicine, University of Munich, Federal Republic of Germany.
The effects of a 1-wk treatment with clonidine (75 micrograms/day twice a
day) and dihydralazine (25 mg/day twice a day) on base-line levels of
plasma atrial natriuretic factor (ANF) and plasma and urinary guanosine
3',5'-cyclic monophosphate (cGMP) and their changes by acute saline
infusion (2 liters) in eight normal subjects were evaluated. Basal ANF was
decreased to 65% in the clonidine group compared with both the control and
dihydralazine groups. Volume loading increased plasma ANF levels by 30-40%
of base-line values in the control and the dihydralazine groups and by 15%
in the clonidine group. Basal plasma and urinary cGMP levels were raised by
30 and 90% in the dihydralazine group compared with both other groups.
Volume loading increased plasma cGMP levels by 40% in the control and
clonidine-treated groups and by 25% in the dihydralazine-treated group. It
is concluded that ANF may contribute to hemodynamic effects of clonidine
but not to those of dihydralazine. Dihydralazine increases plasma and
urinary cGMP, supposedly by direct activation of the soluble guanylate
cyclase.
