Beta adrenergic blockade, regional left ventricular blood flow and ST-segment elevation in canine experimental myocardial ischemia.
The effects of dl-propranolol, d-propranolol, dl-pindolol and dl-practolol on regional myocardial blood flow (assessed by means of tracer microspheres) and on ST-segment elevation in ischemic and nonischemic areas of the canine left ventricle have been investigated. dl-Propranolol and dl-pindolol, but not dl-practolol and d-propranolol, induced blood flow redistribution from the epicardium to the endocardium both in ischemic and nonischemic areas. dl-Propranolol-induced redistribution was abolished by atrial pacing at the control heart rate value. These results indicate that the redistribution phenomenon only occurs if both a bradycardia-inducing beta1 adrenoreceptor blockade and a coronary vessels beta2 adrenoceptor blockade are simultaneously achieved. All four drugs significantly decreased ST-segment elevation in ischemic areas. Under atrial pacing, this effect was abolished with dl-practolol but only reduced with dl- and d-propranol, suggesting that, besides bradycardia, membrane stabilization might be involved in protection against ST-segment elevation in ischemic areas.
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D003326:Coronary Circulation / Q000187:drug effects*; D004285:Dogs; D004562:Electrocardiography; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D008297:Male; D009203:Myocardial Infarction / Q000503:physiopathology*; D010869:Pindolol / Q000494:pharmacology; D011217:Practolol / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D013237:Stereoisomerism
D000319:Adrenergic beta-Antagonists; D011433:Propranolol; D010869:Pindolol; D011217:Practolol