title: The effect of verapamil on reperfusion arrhythmia in canine heart.
abstract: This study was designed to clarify the mechanism of reperfusion arrhythmia and with the effect of verapamil on arrhythmia. In vivo study: Fifty anesthetized dogs were divided into two groups the control group (n = 37) and the verapamil group (n = 13). The left anterior descending coronary artery (LAD) was occluded for 15 min and then reperfused for 5 min. Physiological saline or verapamil (0.4 mg/kg) was infused 5 min prior to the LAD reperfusion. Eleven (30%) of the control dogs developed "reperfusion arrhythmia" (arrhythmia group) but 26 did not (non-arrhythmia group), while in the verapamil group, none of the 13 dogs developed arrhythmia. Immediately after 5 min reperfusion, myocardial plasma membrane and mitochondria were prepared from the normal and the reperfused area. In the arrhythmia group, an increase in free fatty acids (FFA) and a decrease in phospholipids were observed in membrane samples, and the content of calcium in the mitochondria increased in the reperfused myocardium; these changes were not observed in the non-arrhythmia group or the verapamil group. In vitro study: In vitro study consisted of two experiments. In experiment 1, incubation of myocardial plasma membrane with phospholipase (PLase) A2 increased only the unsaturated FFA, while PLase C increased all the detected FFA. In experiment 2, the effects on myocardial membrane potentials induced by PLase A2 and PLase C were studied by using microelectrodes. Each PLase caused a decrease in the resting potential and in the magitude and duration of the action potential.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000200:Action Potentials; D000818:Animals; D001145:Arrhythmias, Cardiac / Q000378:metabolism* / Q000517:prevention & control; D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D004285:Dogs; D004789:Enzyme Activation; D005230:Fatty Acids, Nonesterified / Q000378:metabolism; D005260:Female; D006321:Heart / Q000503:physiopathology; D008297:Male; D008564:Membrane Potentials; D008929:Mitochondria, Heart / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D010477:Perfusion; D010741:Phospholipases A / Q000378:metabolism; D010743:Phospholipids / Q000378:metabolism; D010738:Type C Phospholipases / Q000378:metabolism; D014700:Verapamil / Q000494:pharmacology*
chemical_list: D005230:Fatty Acids, Nonesterified; D010743:Phospholipids; D014700:Verapamil; D010741:Phospholipases A; D010738:Type C Phospholipases; D002118:Calcium