In vitro evaluation of the beta-blocking and electrophysiological properties of mepindolol.
The electrophysiological and beta-blocking effects of mepindolol have been examined in isolated guinea-pig preparations and sheep cardiac Purkinje fibers. Mepindolol did not show selectivity for blocking the chronotropic and inotropic responses to isoprenaline on isolated guinea-pig preparations, and was practically equally potent in blocking the effect of isoprenaline on isolated guinea-pig trachea. Mepindolol 10(-7) M fully antagonized the positive chronotropic effect of isoprenaline (10(-7) M) in Purkinje fibers. However, normal automaticity, action potential characteristics, effective refractory period, membrane responsiveness of Purkinje fibers were unaffected by mepindolol up to 10(-6) M. On the whole, mepindolol appears to be a potent beta-blocker with no cardioselectivity, exerting membrane depressant effect only at concentrations 100-1000 times higher than those exerting effective beta-blockade.
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000818:Animals; D004347:Drug Interactions; D004558:Electric Stimulation; D006168:Guinea Pigs; D006321:Heart / Q000187:drug effects; D006339:Heart Rate / Q000187:drug effects; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D009130:Muscle, Smooth / Q000187:drug effects; D009200:Myocardial Contraction / Q000187:drug effects; D010869:Pindolol / Q000031:analogs & derivatives* / Q000494:pharmacology; D011690:Purkinje Fibers / Q000187:drug effects; D012756:Sheep
D000317:Adrenergic alpha-Antagonists; C015340:mepindolol; D010869:Pindolol; D007545:Isoproterenol