Blood pressure lowering effect of Morus alba is mediated through Ca⁺⁺ antagonist pathway

Morus alba has been used in traditional medicine system for the treatment of hypertension. Our objective was to provide scientific basis for the medicinal use of M. alba in hypertension. The crude extract of Morus alba (Ma.Cr) induced a dose-dependent (10-100 mg kg^-1) fall in the arterial BP in anaesthetized rats. In isolated guinea-pig atria, Ma.Cr caused inhibition of atrial force and rate of spontaneous contractions, similar to that exhibited by verapamil. When tested in rat aortic ring preparations, Ma.Cr at concentration range of 0.1-10 mg mL^-1 relaxed high K⁺ (80 mM) and phenylephrine (PE, 1 μM)-induced contractions and shifted the Ca⁺⁺ dose-response curves to right, like caused by verapamil. These data indicate that the blood pressure lowering action of Morus alba occurred via., Ca⁺⁺ channel blockade pathway, which provides evidence for the pharmacological basis to justify its effectiveness in hypertension.