Cardiac effects of L/N-type Ca2+ channel blocker cilnidipine in anesthetized dogs

Cardiac effects of L/N-type Ca2+ channel blocker cilnidipine were assessed using the halothane-anesthetized canine model. Cilnidipine (1 and 3 μg/kg, i.v.) lowered the mean blood pressure by − 5 and − 14 mm Hg, respectively, without affecting the heart rate or maximum upstroke velocity of left ventricular pressure. Isoproterenol or acetylcholine was intravenously injected to directly or indirectly induce the positive chronotropic responses, respectively. Cilnidipine hardly affected the isoproterenol-induced cardiac responses, but it attenuated the acetylcholine-induced reflex tachycardia to 63–78% of the pre-drug control level. These results suggest that clinically relevant doses of cilnidipine can directly attenuate the sympathetic tone.