The vascular action of aqueous extracts of Foeniculum vulgare leaves.

The vascular effects of aqueous extracts of Foeniculum vulgare leaves were tested using pentobarbital-anaesthetised rats. An intravenous administration of the lyophilized boiled water extract of leaves produced a significant dose-related reduction in arterial blood pressure, without affecting the heart rate or respiratory rate. In contrast the non-boiled aqueous extract showed very little hypotensive activity. The hypotensive effect of the boiling water extract appeared not to be mediated via adrenergic, muscarinic, ganglionic or serotonergic receptors; however, histamine antagonists inhibited the hypotensive effect in a dose-related manner.