title: Contribution of myocardial contractility to myocardial perfusion.
abstract: Myocardial contractility in open-chest anesthetized (sodium pentobarbital) dogs was varied while ventricular pressure, coronary perfusion pressure, and coronary tone were held constant. Under those conditions, changes in regional blood flow should reflect changes only in intramyocardial compression related to the altered inotropic state. Increasing contractility with isoproterenol caused flow to decrease in the outer myocardial layers without change at the subendocardium. When contractility was decreased with pentobarbital, flow at the subendocardium was increased with little change in the outer layers. By manipulating perfusion pressure in the latter experiments it was demonstrated that subendocardial compression was falling from a starting value that was somewhat above peak ventricular pressure.
mesh_terms: D000818:Animals; D003326:Coronary Circulation / Q000187:drug effects; D004285:Dogs; D005260:Female; D006464:Hemoperfusion; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects; D010424:Pentobarbital / Q000494:pharmacology; D011312:Pressure
chemical_list: D010424:Pentobarbital; D007545:Isoproterenol