Preferential increase in subendocardial perfusion produced by endothelium-dependent vasodilators.
The transmural distribution of myocardial blood flow across the left ventricles of anesthetized dogs was measured with radioactive microspheres during intracoronary infusion of the endothelium-dependent vasodilators acetylcholine (10 micrograms/min), adenosine triphosphate (ATP; 20 micrograms/min), and arachidonic acid (600 micrograms/min) and the endothelium-independent vasodilator nifedipine (5 micrograms/min). These compounds were administered before and after a 30 min intracoronary infusion of the phospholipase A2 inhibitor quinacrine (300 micrograms/min). Acetylcholine, ATP, and arachidonic acid produced significant (p less than .05) increases in transmural blood flow and in the ratio of subendocardial to subepicardial blood flow (endo/epi) when compared with control. Infusion of quinacrine did not affect this ratio and did not block the increase in transmural blood flow produced by each agent; however, it did block the redistribution of flow to the subendocardium. In contrast, there was no change in endo/epi during intracoronary infusion of nifedipine before and after quinacrine. These results suggest that endothelium-dependent vasodilators produce a preferential increase in subendocardial perfusion via a product of unsaturated fatty acid metabolism.
D000818:Animals; D003326:Coronary Circulation; D004285:Dogs; D004699:Endocardium / Q000502:physiology*; D004727:Endothelium / Q000502:physiology*; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D008297:Male; D010741:Phospholipases A / Q000037:antagonists & inhibitors; D054467:Phospholipases A2; D011796:Quinacrine / Q000494:pharmacology; D012039:Regional Blood Flow / Q000187:drug effects; D014665:Vasodilator Agents / Q000494:pharmacology*
D014665:Vasodilator Agents; D010741:Phospholipases A; D054467:Phospholipases A2; D011796:Quinacrine