title: Effects of selective and nonselective beta-adrenoceptor antagonism on isoproterenol-stimulated myocardial potassium uptake in the intact dog.
abstract: In intact anesthetized dogs, we measured myocardial potassium uptake, as calculated from the aortocoronary sinus difference in potassium concentration and myocardial blood flow, before and during beta-adrenergic stimulation with isoproterenol. Isoproterenol (10 and 30 ng/kg/min, n = 16) lowered arterial potassium concentration from 3.48 +/- 0.08 mmol/L by 0.20 +/- 0.07 and 0.32 +/- 0.06 mmol/L, coronary sinus potassium from 3.45 +/- 0.08 mmol/L by 0.20 +/- 0.06 and 0.35 +/- 0.06 mmol/L, increasing/myocardial potassium uptake from 1.94 +/- 0.99 mumol/min to 2.33 +/- 0.97 and 5.36 +/- 1.29 mumol/min. Unselective beta blockade (propranolol 0.1 mg/kg) significantly attenuated the fall in arterial and coronary sinus serum potassium and the increase in myocardial potassium uptake. Selective beta 1 blockade (metoprolol 0.1 mg/kg) did not significantly influence these effects. We conclude that beta-adrenergic stimulation increases myocardial potassium uptake, lowering serum potassium in the coronary bed, in addition to causing a systemic hypokalemia. This effect is mediated predominantly by beta 2 adrenoceptors.
authors: Medizinische Universitäts-Klinik, Würzburg, Federal Republic of Germany.
authors: D
authors: D
authors: Elsner
authors: E P
authors: EP
authors: Kromer
authors: A J
authors: AJ
authors: Riegger
mesh_terms: D000818:Animals; D004285:Dogs; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D007008:Hypokalemia / Q000139:chemically induced; D007545:Isoproterenol / Q000494:pharmacology*; D008297:Male; D008790:Metoprolol / Q000494:pharmacology; D009206:Myocardium / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism*; D011943:Receptors, Adrenergic, beta / Q000187:drug effects*
chemical_list: D011943:Receptors, Adrenergic, beta; D008790:Metoprolol; D007545:Isoproterenol; D011188:Potassium