title: Beta adrenergic and muscarinic cholinergic receptors in canine myocardium. Effects of ischemia.
abstract: Experimental myocardial ischemia produced in dogs by proximal left anterior descending coronary artery ligation is accompanied by relatively rapid (1 h) increases in the number of (-) [3H]dihydroalprenolol binding sites without changing their dissociation constants in ischemic left ventricular tissue. The changes, persist for at least 8 h and are accompanied by marked decreases in myocardial tissue ischemic region norepinephrine content. In contrast, in the same canine model 1 h of proximal left anterior descending coronary artery ligation did not result in a significant change in the number of [3H]quinuclidynl benzilate binding sites of their dissociation constants. However, the number of [3H]quinuclidynl benzilate binding sites (muscarinic cholinergic receptors) are 50--70% greater than (-) [3H]dihydroalprenolol binding sites (beta adrenergic receptors) in canine left ventricular tissue. Thus, the data suggest that proximal left anterior descending coronary artery occlusion for 1 h significantly increases the number of beta adrenergic receptors in ischemic left ventricular tissue without changing the number of muscarinic cholinergic receptors. Whether the ischemia-produced increase in cardiac beta-receptor content is causally related to increased cyclic AMP levels that develop in ischemic tissue and/or an etiologic factor in arrhythmias originating from ischemic myocardial tissue will have to be determined in additional studies.
mesh_terms: D000818:Animals; D003327:Coronary Disease / Q000378:metabolism*; D003331:Coronary Vessels / Q000601:surgery; D004082:Dihydroalprenolol / Q000378:metabolism; D004285:Dogs; D005260:Female; D008026:Ligation; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D009638:Norepinephrine / Q000378:metabolism; D011813:Quinuclidinyl Benzilate / Q000378:metabolism; D011941:Receptors, Adrenergic / Q000302:isolation & purification*; D011943:Receptors, Adrenergic, beta / Q000302:isolation & purification* / Q000378:metabolism; D011950:Receptors, Cholinergic / Q000302:isolation & purification*; D011976:Receptors, Muscarinic / Q000302:isolation & purification* / Q000378:metabolism
chemical_list: D011941:Receptors, Adrenergic; D011943:Receptors, Adrenergic, beta; D011950:Receptors, Cholinergic; D011976:Receptors, Muscarinic; D004082:Dihydroalprenolol; D011813:Quinuclidinyl Benzilate; D009638:Norepinephrine