Centrally induced hypotension unreleated to alpha-adrenergic stimulation.

Central hypotension is induced by erythro-1-(1-[2-(1,4 - benzodioxan - 2 - yl) - 20H - ET] - 4 - piperidyl) - 2 - benzimidazolinone (R28935), as evidenced by local injections into the cisterna magna of anaesthetized dogs. This hypotensive effect is not inhibited by piperoxan, 100 mug/kg s.o. R28935, contrary to clonidine or norepinephrine, does not provoke vasoconstriction in the perfused isolated artery of the rabbit ear. Very low doses of R28935 antagonize vasoconstriction induced by KC1-depolarization. The centrally-induced hypotension is not due to alpha-adrenergic stimulation.