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 Ca2+ 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