Effects of pipecuronium and pancuronium on the isolated rabbit heart

We have studied the effects of pipecuronium and pancuronium on myocardial contractility and heart rate in two different animal preparations. Pipecuronium and pancuronium produced no change in isometric contraction of rabbit atria. The chronotropic effects of pipecuronium, pancuronium and vecuronium were investigated using acetylcholine as an agonist in isolated perfused rabbit heart. Pancuronium but not pipecuronium or vecuronium, produced a significant degree of antagonism to the bradycardia produced by acetylcholine.