A radioangiographic study of the effects of catecholamines on uteroplacental blood flow in the rhesus monkey.

Two placental radioangiographies were performed with a 20-min interval in ten lightly anesthetized rhesus monkeys. Amniotic and aortic pressures, as well as the maternal ECG, were continuously monitored. Norepinephrine or metaproterenol was administered in a low dose which did not cause general cardiovascular effects, prior to the second angiography. Norepinephrine appeared to cause constriction and metaproterenol, dilatation of the uteroplacental vessels. These effects could be diminished or abolished by an alpha- or beta-adrenergic blocking agent, respectively, and thus would appear to be caused by stimulation of adrenergic receptors in the uteroplacental vasculature.