Affinity of nortriptyline to muscarinic receptors in the bladder and ileum of man and guinea-pig.
The antagonism by nortriptyline of carbachol- or urecholine-induced contractions was studied in strips of ileum and bladder derived from man and guinea-pig. Analyses of the results by the dose ratio method (Schild plots) showed significant differences in the affinities of the relevant muscarinic receptors to the antagonist: The Ki values in microM were as follows: Human ileum, 0.938; human bladder, 0.298; guinea-pig ileum, 0.159; guinea-pig bladder, 0.333 and 0.453. In man, the higher affinity of the drug to the receptors in the bladder than to those in the ileum may be of consequence in its therapeutic application as an antienuretic agent.
D000818:Animals; D001626:Bethanechol Compounds / Q000037:antagonists & inhibitors; D002217:Carbachol / Q000037:antagonists & inhibitors; D006168:Guinea Pigs; D006801:Humans; D007082:Ileum / Q000294:innervation; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000502:physiology*; D009661:Nortriptyline / Q000494:pharmacology*; D009928:Organ Specificity; D011976:Receptors, Muscarinic / Q000187:drug effects*; D001743:Urinary Bladder / Q000294:innervation
D001626:Bethanechol Compounds; D011976:Receptors, Muscarinic; D002217:Carbachol; D009661:Nortriptyline