Do pipecuronium and rocuronium affect human bronchial smooth muscle?
BACKGROUND
Muscle relaxants affect nicotinic and muscarinic receptors. Interaction of muscle relaxants with muscarinic receptors of human airways has been studied incompletely.


METHODS
The effects of pipecuronium bromide (long-acting, nondepolarizing) and rocuronium bromide (intermediate-acting, nondepolarizing) on prejunctional and postjunctional muscarinic receptors were studied in 96 isolated human bronchial rings from 12 patients. Contractile isometric responses to electric field stimulation of pilocarpine-stimulated and nonstimulated M2 muscarinic receptors were compared before and after incubation with the two muscle relaxants. The effect on postjunctional muscarinic receptors was studied by comparing acetylcholine concentration-response curves before and after incubation with the two muscle relaxants.


RESULTS
Pipecuronium bromide, but not rocuronium bromide, inhibited pilocarpine-stimulated prejunctional M2 muscarinic receptors. Neither pipecuronium bromide nor rocuronium bromide had significant inhibitory effects on nonstimulated M2 muscarinic receptors and on postjunctional M3 muscarinic receptors.


CONCLUSIONS
The inhibitory effect of pipecuronium bromide on pilocarpine-stimulated prejunctional M2 muscarinic receptors occurred at clinical concentrations.
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Servizio di Anestesia e Rianimazione, Istituto Nazionale per la Ricerca sul Cancro, Genova, Italy. rehder.kai@Mayo.edu
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Nicosia
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Rehder
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D000109:Acetylcholine / Q000378:metabolism; D000328:Adult; D000368:Aged; D000732:Androstanols / Q000494:pharmacology*; D001980:Bronchi / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D008875:Middle Aged; D018721:Muscarinic Agonists / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects* / Q000378:metabolism; D003473:Neuromuscular Nondepolarizing Agents / Q000494:pharmacology*; D010862:Pilocarpine / Q000494:pharmacology; D017300:Pipecuronium / Q000494:pharmacology*; D043585:Receptor, Muscarinic M2; D043587:Receptor, Muscarinic M3; D011976:Receptors, Muscarinic / Q000187:drug effects* / Q000378:metabolism; D000077123:Rocuronium
D000732:Androstanols; D018721:Muscarinic Agonists; D003473:Neuromuscular Nondepolarizing Agents; D043585:Receptor, Muscarinic M2; D043587:Receptor, Muscarinic M3; D011976:Receptors, Muscarinic; D010862:Pilocarpine; D017300:Pipecuronium; D000109:Acetylcholine; D000077123:Rocuronium