Pharmacological activity of the new calcium antagonist, lacidipine, on isolated preparations.

1. The calcium-channel blocking activity of lacidipine has been studied compared with that of nifedipine and verapamil on the isolated rabbit heart and aorta. 2. All the compounds induced a dose-dependent negative inotropic effect (10(-8)-10(-5) M); although lacidipine showed less, but longer lasting, activity. 3. Lacidipine showed a weak negative chronotropic effect and nifedipine was ineffective. Only verapamil strongly decreased the heart rate. 4. The three calcium antagonists abolished vasopressin-induced coronary spasm and inhibited partially metoxamine-induced coronary spasm. Only lacidipine reduced basal coronary pressure. 5. In the aortic strips, all the compounds antagonized KCl-induced contractions, and they exerted a partial effect on noradrenaline- and angiotensin II-induced contractions.