Attenuation of ischaemia-induced regional myocardial acidosis by bevantolol, a beta 1-adrenoceptor antagonist, in dogs.
In dogs anaesthetized with pentobarbital, the left anterior descending coronary artery (LAD) was occluded for 90 min. so that about 1/2 of the original flow was allowed to flow (partial occlusion). Bevantolol (a beta 1-adrenoceptor antagonist) or propranolol (a reference drug) was injected intravenously 30 min. after partial occlusion. Regional myocardial pH was measured by a micro glass pH electrode inserted in the LAD area. Partial occlusion decreased myocardial pH by 0.62 to 0.74. Bevantolol (1.0 mg/kg) or propranolol (1.0 mg/kg) significantly increased myocardial pH, that had been decreased by partial occlusion, within 60 min. after the injection. Restoration of myocardial [H+] (defined as return towards a lower [H+] to the preocclusion level) (calculated from the pH data) induced by bevantolol and that induced by propranolol were 64.0 and 66.4% (measured 60 min. after the injection), respectively. Bevantolol or propranolol decreased heart rate also. Even in the paced heart, bevantolol restored the myocardial [H+] that had been increased by partial occlusion. These results suggest that bevantolol has a favorable effect on the ischaemic myocardium as has propranolol, and that the pH effect of bevantolol is not primarily due to a decrease in heart rate.
Hino
T
T
Department of Pharmacology, Asahikawa Medical College, Japan.
Sakai
K
K
Ichihara
K
K
Abiko
Y
Y
D000138:Acidosis / Q000378:metabolism / Q000517:prevention & control*; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D003327:Coronary Disease / Q000378:metabolism*; D003331:Coronary Vessels / Q000502:physiology; D004285:Dogs; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D008297:Male; D009206:Myocardium / Q000378:metabolism; D011412:Propanolamines / Q000494:pharmacology*; D011433:Propranolol / Q000494:pharmacology
D000319:Adrenergic beta-Antagonists; D011412:Propanolamines; C021148:bevantolol; D011433:Propranolol