The interaction of pancuronium and vecuronium with cardiac muscarinic receptors.
The interaction of vecuronium, a monoquaternary analogue of pancuronium, with the cardiac muscarinic receptors in canine hearts was investigated in vitro by [3H] QNB binding assay and compared with that of pancuronium. Both pancuronium and vecuronium, which are nicotinic antagonists of competitive types, inhibited the binding of [3H] QNB to cardiac muscarinic receptors with values of IC50 of 5.41 X 10(-7) mol/l and 3.97 X 10(-6) mol/l respectively. According to the Kd and Bmax values on the Scatchard plot, pancuronium, while not influencing the number of receptors, had a 3-fold greater inhibitory effect than vecuronium on the affinity of the muscarinic receptors. The KI values of vecuronium and pancuronium showed that pancuronium had a 7.3-fold greater affinity with the receptors than vecuronium. We concluded that vecuronium had a direct inhibitory action on the binding of [3H] QNB to the canine heart muscarinic receptors, but this action was much weaker than pancuronium.
D000818:Animals; D004285:Dogs; D004347:Drug Interactions; D006321:Heart / Q000187:drug effects*; D006439:Hemodynamics / Q000187:drug effects; D066298:In Vitro Techniques; D007700:Kinetics; D010197:Pancuronium / Q000494:pharmacology*; D011813:Quinuclidinyl Benzilate; D011976:Receptors, Muscarinic / Q000187:drug effects*; D014673:Vecuronium Bromide / Q000494:pharmacology*
D011976:Receptors, Muscarinic; D011813:Quinuclidinyl Benzilate; D014673:Vecuronium Bromide; D010197:Pancuronium