Effects of coronary vasodilators on large and small coronary arteries of dogs

Using the isolated perfused heart preparation supported by a donor the effects of vasodilators on the large conductance artery were studied and were compared with those on the small resistive artery and arterioles. Nitroglycerin produced a preferential dilation of the large conductance artery, while dipyridamole produced a dilation only of the small resistive artery and arterioles. Among the "calcium antagonistic" vasodilators tested, only diltiazem produced a dilatation of the large conductance artery, verapamil and nifedipine producing a dilatation only of the small resistive artery and arterioles. These findings indicate that the mechanism of contraction of the large conductance artery is different from that of the small resistive artery and arterioles.