Determinants of delayed preconditioning against myocardial stunning in chronically-instrumented pigs.
To test the hypothesis that a critical stenosis prevents delayed preconditioning against stunning, studies were conducted in pigs chronically-instrumented with occluders and segment-shortening crystals. In the setting of a critical stenosis, a preconditioning stimulus of repetitive brief occlusions resulted in infarction. Thereafter, a single 10-minute occlusion was used as the preconditioning stimulus. Delayed preconditioning against stunning was documented on subsequent days by the deficit-of-function following brief repetitive occlusions. In contrast to experiments in the naïve heart, the deficit-of-function improved on the day after a single 10-minute occlusion (from 60+/-14 to 24+/-6 arbitrary units, p=0.003), and similar improvement occurred when reperfusion was performed through a critical stenosis (32+/-6 units, p=0.02 vs. naïve and p=0.34 vs. no stenosis). Delayed preconditioning also reduced the frequency of ventricular fibrillation, and produced a 4-fold increase in both calcium-dependent and calcium-independent NOS activity. Thus, a critical stenosis did not prevent delayed preconditioning against stunning.
Fallavollita
James A
JA
VA Western New York Health Care System at Buffalo, the Center for Research in Cardiovascular Medicine and the Division of Cardiovascular Medicine, Department of Medicine, University at Buffalo, Buffalo, NY, USA. jaf7@buffalo.edu
D000818:Animals; D001794:Blood Pressure; D003326:Coronary Circulation; D023921:Coronary Stenosis / Q000150:complications / Q000378:metabolism / Q000503:physiopathology / Q000628:therapy*; D004195:Disease Models, Animal; D006339:Heart Rate; D019157:Ischemic Preconditioning, Myocardial; D009200:Myocardial Contraction; D015425:Myocardial Reperfusion / Q000009:adverse effects; D017682:Myocardial Stunning / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology / Q000517:prevention & control*; D009206:Myocardium / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000378:metabolism; D020127:Recovery of Function; D013552:Swine; D013997:Time Factors; D014693:Ventricular Fibrillation / Q000209:etiology / Q000517:prevention & control; D016277:Ventricular Function, Left; D017725:Ventricular Pressure
D009569:Nitric Oxide; D019001:Nitric Oxide Synthase