TY - JOUR T1 - BLOCKADE OF RESPONSES OF ISOLATED MYOCARDIUM TO EPINEPHRINE JF - Journal of Pharmacology and Experimental Therapeutics JO - J Pharmacol Exp Ther SP - 186 LP - 191 VL - 133 IS - 2 AU - Mark Nickerson AU - Gordon C-M. Chan Y1 - 1961/08/01 UR - http://jpet.aspetjournals.org/content/133/2/186.abstract N2 - The ability of various classical adrenergic blocking agents and of dichloroisoproterenol (DCI) to block the chronotropic and inotropic responses of the mammalian myocardium to epinephrine has been re-evaluated on isolated atria and papillary muscles. Maximum tolerated doses of Dibenamine, phenoxybenzamine (Dibenzyline), azapetine (Ilidar), piperoxan (933F, Benodaine), or Hydergine did not depress either response, except in preparations and under conditions in which a comparable decrease in responses to calcium occurred. DCI, in very low concentrations, selectively inhibited both chronotropic and inotropic responses to epinephrine. It was concluded that the classical adrenergic blocking agents do not affect "physiological" responses of the heart to adrenergic stimuli. Several factors which may have contributed to recent contrary reports have been discussed. 1961 by The American Society for Pharmacology and Experimental Therapeutics ER -