Abstract
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.
Footnotes
- Received February 20, 1961.
- 1961 by The American Society for Pharmacology and Experimental Therapeutics
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