Effect of antidepressant drugs on the contraction of the isolated rat ileum induced by CaCl2
Puche, E.; Bolaños, J.
Archivos de Farmacologia y Toxicologia 9(3): 251-256
1983
ISSN/ISBN: 0304-8616 PMID: 6673662 Document Number: 217771
Using the isolated ileum of rats depolarized with K and contracted by CaCl2 in a Ca-free medium, the existence of a competitive antagonism (pA2 calculated) was demonstrated between tricyclic antidepressant drugs [amitriptyline, imipramine, maprotiline and nortriptyline] capable of relaxing smooth muscle and Ca in concentrations between 5 .times. 10-7 M and 10-6 M. Non tricyclic antidepressants [mianserin, nomifensine and viloxazine], which relax smooth muscle scarcely or not at all, only affected the ileum response to Ca at concentrations > 10-5 M. The tricyclic antidepressants may produce this effect by blocking the influx of Ca, which is a mechanism of action different from the generally accepted theory that the tricyclics relax the smooth muscle by blocking the muscarinic receptors in the intestine.