The Vascular Actions of Aqueous Extract of Lippia multiflora

Abstract

Intravenously administered aqueous leaf extract (6.3 to 12.5 mg/kg) in anaesthetised cats and (3.2 to 6.3 mg/kg) in anaesthetised rats, produced a significant fall (P < 0.05, n = 10) in the mean, systolic and diastolic blood pressure by as much as 75 ± 5.0 mm Hg in cats and 35 ± 10.00 mm Hg in rats. On the raised arterial perfusion pressure of the rabbit central ear artery preparation, the extract (12.5-50 µg) produced a transient rise in perfusion pressure, which was followed by a more significant and prolonged fall in the perfusion pressure. Phentolamine (1.0 µg/ml) antagonised the transient rise and propranolol (1.0 µg/ml abolished the fall in perfusion pressure. The results suggested: that vasodilatation, resulting from a combination of alpha-adrenoceptor blockade and beta-adrenoceptor stimulant action of the extract, aided by skeletal muscle relaxation might be responsible for the blood pressure lowering effect of the extract.