[Coronary-angiographic demonstration of the dilating effect of dipyridamole on coronary arteries and its inhibition by caffeine (author's transl)].

Selective coronary cineangiographies are performed repeatedly in 13 mongrel dogs. The contrast medium itself has no demonstrable dilating effect upon the vessels. After the first injection of 0.2 mg/kg of dipyridamole the left anterior coronary artery is significantly (p less than 0.001) dilated, which is in contrast to some results described in literature. Immediately after an injection of high doses of caffeine (10 mg/kg) the previously enlarged coronary diameter decreases significantly (p less than 0.001). During the action of caffeine subsequent infections of dipyridamole result in a very small, or no change in coronary diameter. The coronary-dilating effect of dipyridamole can be inhibited by high doses of caffeine (10 mg/kg).