Effects of drugs and sympathetic nerve stimuation on retrograde coronary blood flow in dogs with experimental coronary occlusion.

Effects of nitroglycerin, dipyridamole, adenosine, reactive hyperemia, propranolol, norepinephrine and sympathetic nerve stimulation on retrograde coronary blood flow were investigated in dogs with experimental coronary occlusion. The retrograde blood flow (RF), pressure and conductance of the occluded left anterior descending coronary artery were measured and compared with the flow (CF), pressure and conductance of the non-occluded circumflex artery. The RF increased during sympathetic nerve stimulation and after the administration of nitroglycerin and norepinephrine, while it decreased during reactive hyperemia and following injection of dipyridamole, adenosine and propranolol. The RF/CF ratio was increased by nitroglycerin and propranolol, whereas it was lowered by dipyridamole and adenosine. The results suggest that nitroglycerin and propranolol may produce a redistribution of myocardial blood flow and that the collateral vessels are little influenced by sympathetic nerve stimulation.