Abstract
The cardiovascular effects of an aqueous extract of seeds of Casimiroa edulis were assessed in pentobarbital-anesthesized dogs. The extract produced marked hypotension
which lasted more than two hours; it was accompanied by moderate and less persistent
bradycardia. The histaminergic nature of these effects was investigated in animals
pretreated with the specific antagonists diphenhydramine, cimetidine, or a combination
of both agents. These experiments showed that both H1- and H2-receptors were involved in the hypotensive response, while the bradycardia was mediated
solely through an H1-mechanism. In open-chest dogs instrumented for recording cardiac output (ascending
aortic flow), left ventricular contractility (dp/dt), central venous pressure (superior
vena cava), systemic blood pressure, heart rate, total peripheral resistance and stroke
volume, the extract decreased blood pressure and peripheral resistance and increased
cardiac output and stroke volume, without modifying the other parameters. It was concluded
that the cardiovascular pattern of Casimiroa edulis in the dog is that of a peripheral arterial vasodilator and that it increases cardiac
output by reducing left ventricular afterload.
Key words
Casimiroa edulis
- hypotension - peripheral vasodilatation - hemodynamics - histamine receptors
