THE EFFECTS OF CASSIA-ABBREVIATA ON RAT-BLOOD PRESSURE

The effects of a crude extract of the stem bark of Cassia abbreviata o n mean arterial pressure in anaesthetized rats were investigated. Bolu s injections of the stem bark elicited a transitory fall in blood pres sure which was dose-dependent. The depressor response was not blocked by atropine nor propranolol thus indicating that muscarinic and beta 2 receptors are not involved. However it was partially blocked by diphe nhydramine, and H1 antagonist. The latter also partially blocked the d epressor response to histamine which is mediated partially through bot h H1 and H2 receptors. It is concluded that the stem bark of C. abbrev iata contains histamine or a chemically related substance and that it is this component which is responsible for lowering the blood pressure .