A CENTRALLY MEDIATED PERIPHERAL HYPOTENSIVE EFFECT OF -METHYLDOPA

¹ Department of Pharmacology, The Albany Medical College of Union University, Albany, New York

To determine whether -methyldopa (-MD) could affect the peripheral circulation by a central action, it was perfused through the isolated in situ cat brain having reflex and/or tonic sympathetic control over the circulations of the body and an isolated perfused hind limb of the same cat. A centrally mediated hypotension, bradycardia and decreased hind limb vascular resistance were consistent findings on brain perfusion of -MD in concentrations ranging from 25 to 200 g/mI of perfusing blood. Norepinephrine levels in the hypothalamus, midbrain and medulla oblongata determined one-half one and two hours after -MD perfusion were not significantly lowered, indicating a lack of correlation between the centrally mediated peripheral hypotension and effects on brain norepinephrine. The results are interpreted as an unequivocal demonstration of a centrally mediated hypotensive effect of -MD in the nonhypertensive anesthetized cat.