RESUMO
The cardiovascular effects of an extract from the bark of the tropical plant, Anacardium occidentale (AO), was investigated in anaesthetized open-chest dogs. Measuring concurrrent changes in femoral arterial blood pressure, ECG (Lead II), heart rate and contractile force, it was observed that single injections of AO induced sustained hypotension associated with tachycardia and reversible ECG alterations. These changes were not observed during continuous AO infusions. Cardiovascular effects (pressor responses and increased contractility) produced by intravenous adrenaline and noradrenaline were not abolished by AO pre-treatment. However, noradrenaline induced arrhythmais were antagonized. It is concluded that AO exerts both hypotensive and antiarrhythmic effects. In the West Indies a wide variety of local plants are used in the treatment of several illnesses. A screening programme to investigate the pharmacological basis of this folk medicine was initiated at the University of the West Indies in 1962. From this investigation, a toxic principle-hypoglycin A isolated from the unripe fruit and seed of the ackee (Blighia sapidda) was shown to be hypoglycemic, teratogenic and anti-tumour (Gaskin and Persaud, 1967). On the other hand, the periwinkle plant (Vinca rosa) contained active principles-vinblastine and vincristine now used in the therapeutic treatment of leukemia (Nobel et al., 1958; Johnson et al., 1959). Aqueous extract of Anacardium occidentale is employed in the treatment of diabetes mellitus. It has been reported that intravenous administration of a tincture of the bark of this plant lowers blood sugar levels for several hours (Ardiuno et al., 1951). In preliminary experiments, no antidiabetic properties could be demonstrated when either an aqueous or alcoholic extract of the bark of this plant was injected intraperitoneally in rats. On the other hand, intravenous administration of a saline solution of the crude solid obtained from the alcoholic extractive, induced a prolonged hypotensive effect in pentobarbital-anaesthetized dogs (West, 1970). The present study was initiated to investigate further the cardiovascular properties of this crude solid isolated from the bark of Anacardium occidentale (AU)
