The Vascular Effects of Ilex pubescens

Abstract

Maodongqing (MDQ) is the common name for the evergreen plant, Ilex pubescens Hook et Arn. In China, an aqueous extract is available for parenteral administration and is used for the treatment of cardiovascular diseases. Among its several pharmacological actions, it is known to be hypotensive. In the present study, its direct vasorelaxing effect was investigated. In rats, MDQ produced two consecutive hypotensive responses. The early response did not involve the adrenergic, cholinergic, histaminergic, prostaglandinergic and bradykininergic systems. The second response was abolished by antihistamines or repeated injection of MDQ (tachyphylàxis). In dogs, only the late response was seen and it was blocked by antihistamines. It seems that when given intravenously, MDQ releases histamine.