Pharmacology of Casimiroa edulis; Part I. Blood Pressure and Heart Rate Effects in the Anesthetized Rat

Abstract

The effect of an alcoholic extract of seeds of Casimiroa edulis on blood pressure and heart rate was determined in rats anesthetized with pentobarbital and compared with that of histamine. The extract induced hypotension, accompanied at high doses by tachycardia. Hypotension after histamine was more transient and was not accompanied by changes in heart rate. Experiments with a variety of autonomic antagonists revealed that extract-induced hypotension was not mediated by histamine H₂, muscarinic, or beta-adrenergic receptors, but involved an H₁ mechanism. After H₁ blockade, the depressor response was reversed to a pressor effect, mediated by alpha-adrenoceptor stimulation. The increase in heart rate was due in part to H₁ and in part to beta-adrenergic receptor activation. It was suggested that imidazole derivatives could be responsible for the depressor effect observed. The pressor response could be caused by these or other components of the extract.

Key words

Casimiroa edulis - effect on blood pressure - effect on heart rate - imidazole derivatives - pharmacology