title: Isoproterenol-induced myocardial ischemic injury in the rabbit: functional and ultrastructural alterations.
abstract: The functional and ultrastructural changes observed during myocardial ischemic injury (MII) in the rabbit are described. MII was induced by repeated subcutaneous injections of increasing doses of isoproterenol (ISO; 0.5 mg/kg on day 1, to 15.5 mg/kg on day 15). Measurement of cardiovascular changes revealed a significant decrease in the mean arterial pressure and an increase in heart rate of the ISO-treated animals. ISO treatment also initiated a variety of atrial and ventricular arrhythmias, including ventricular fibrillation, as well as significant ST segment elevations and the appearance of Q waves. Electron-microscopic analysis of hearts from ISO-treated animals showed accumulation of lipid and depletion of glycogen. The myofibrils had poorly defined Z bands and appeared as a homogeneous mass. The most marked effects of ISO treatment were on the mitochondria, which appeared swollen and fragmented. The mitochondrial cristae were also disrupted and fragmented. A few amorphous electron-dense bodies were observed in and around the mitochondria. The changes observed in this study are qualitatively similar to those observed in the rabbit following coronary artery ligation.
mesh_terms: D000818:Animals; D003327:Coronary Disease / Q000139:chemically induced / Q000473:pathology* / Q000503:physiopathology; D006439:Hemodynamics; D007545:Isoproterenol; D008297:Male; D008854:Microscopy, Electron; D009206:Myocardium / Q000648:ultrastructure; D011817:Rabbits
chemical_list: D007545:Isoproterenol