Biochemical basis for reperfusion arrhythmias.
This study was designed to clarify the biochemical mechanism of reperfusion arrhythmias. Forty-three anesthetized dogs were divided into three groups; the occlusion group (n = 7), the reperfusion group (n = 24), and a group treated with the alpha 1-adrenergic blocker, bunazosin (n = 12). In the occlusion group, the left anterior descending coronary artery (LAD) was occluded for 15 min. In the reperfusion group and the bunazosin group, LAD was occluded for 15 min and then reperfused for 5 min with physiological saline or bunazosin (0.5 mg/kg) infused 5 min prior to the LAD occlusion. Seven dogs (29%) of the reperfusion group developed reperfusion arrhythmias, but 17 did not. In the bunazosin group, none developed arrhythmias. Immediately after the end of occlusion or reperfusion, myocardial plasma membrane and mitochondria were prepared from the normal and ischemic areas or the normal and reperfused areas. Phospholipase activity, phospholipid content, and free fatty acid (FFA) levels were determined. The mitochondrial calcium content was also measured. In the reperfusion-with-arrhythmias group, the content of calcium in the mitochondria obtained from the reperfused area and phospholipase activity in the reperfused myocardium was elevated significantly compared with those in the reperfusion-without-arrhythmias group. Phospholipid content in the plasma membrane prepared from the reperfused area also decreased significantly in the reperfusion-with-arrhythmias group. The FFA levels in the plasma membrane prepared from the reperfused area were increased. In the reperfusion-without-arrhythmias group and the bunazosin group, these changes were not observed. Fifteen minutes occlusion alone did not induce these changes observed in the reperfusion-with-arrhythmias group.(ABSTRACT TRUNCATED AT 250 WORDS)
D000317:Adrenergic alpha-Antagonists / Q000627:therapeutic use; D000818:Animals; D001145:Arrhythmias, Cardiac / Q000209:etiology* / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D003326:Coronary Circulation; D003327:Coronary Disease / Q000150:complications*; D004285:Dogs; D005260:Female; D007473:Ion Channels / Q000378:metabolism; D008297:Male; D008929:Mitochondria, Heart / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism*; D010740:Phospholipases / Q000378:metabolism; D011799:Quinazolines / Q000627:therapeutic use
D000317:Adrenergic alpha-Antagonists; D007473:Ion Channels; D011799:Quinazolines; C018176:bunazosin; D010740:Phospholipases; D002118:Calcium