In current study, we describe blood pressure (BP)-lowering, endothelium-dependent, and independent vasodilator and cardio-modulatory actions of Carum roxburghianum seed. The crude extract of C. roxburghianum seed (Cr.Cr) induced dose-dependent (10-100mg/kg) fall in arterial BP of anaesthetized rats. In isolated rabbit aorta, Cr.Cr (0.3-10mg/mL) inhibited high K+ (80mM) and phenylephrine (PE, 1M)-induced contractions, like verapamil and papaverine. In endothelium-intact rat aortic preparations, Nomega-nitro-L-arginine methyl ester hydrochloride-sensitive vasodilator activity was observed with Cr.Cr, which also relaxed endothelium-denuded aorta tissues. In guinea-pig atria, Cr.Cr initially caused mild cardiac stimulation, followed by inhibiti...