Blood pressure lowering effect of olive is mediated through calcium channel blockade

Olive (Olea europea) is used in traditional medicine as a remedy for hypertension. The aqueous–methanolic crude extract of O. europea fruit (OeF.Cr) was studied in anaesthetized rats and its possible mechanism was elucidated using isolated cardiovascular preparations. Intravenous administration of OeF.Cr produced a dose-dependent (30–100 mg/kg) fall in arterial blood pressure in normotensive anaesthetized rats. This effect remained unaltered in atropinized animals. In the in vitro studies OeF.Cr (0.1–3.0 mg/ml) inhibited spontaneously beating guinea-pig atria. Moreover, it relaxed K⁺ and/or phenylephrine-induced contractions of rabbit aortic preparations over a dose range of 0.1–3.0 mg/ml, suggesting calcium channel blockade (CCB). The CCB effect was confirmed when pretreatment of the vascular preparations with OeF.Cr produced a dose-dependent rightward shift of the Ca^2?+? dose–response curves, similar to verapamil. These results suggest that the blood pressure lowering effect of olive is mediated through CCB, justifying its use in hypertension.