Journal of Applied Physiology, Vol 68, Issue 2 527-532, Copyright © 1990 by American Physiological Society
Influence of the renin-angiotensin system on human forearm blood flow
C. Stadeager, B. Hesse, O. Henriksen, F. Bonde-Petersen, J. Mehlsen and S. Rasmussen
Department of Clinical Physiology, Hvidovre Hospital, Copenhagen, Denmark.
Although angiotensin II is a potent vasoconstrictor agent in all tissues,
including the human forearm, equivocal effects on forearm blood flow (FBF)
have been found after angiotensin blockade. In 13 healthy Na(+)-depleted
subjects FBF was measured by the 133Xe washout technique; subcutaneous and
muscle blood flows were determined separately. FBF was measured during
supine rest, after the arm was lowered, and during lower body negative
pressure (LBNP). The measurements were repeated during intra-arterial
saralasin infusion in six subjects and after intravenous administration of
enalapril in seven subjects. FBF decreased and forearm vascular resistance
(FVR) increased during arm lowering and LBNP, as the result of local and
central adrenergic reflexes, respectively. We observed similar FBF and FVR
values after both saralasin and enalapril, except for a decrease in FVR at
rest after enalapril. It is concluded that, in the human forearm,
angiotensin II is not necessary for sympathetic vasoconstrictor reflexes
but may, through a central effect, have some influence on arteriolar tone
at rest.
