Effects of the new imidazopyridine CL 86-02-01 on isolated papillary muscle of guinea-pig hearts.

Inotropic activity and the effect of CL 86-02-01 (2-(3-methoxy-5-methylsulfinyl-2-thienyl)-1H-imidazo[4,5-c]pyridine hydrochloride, CAS 109 792-24-7) on membrane resting and action potentials were studied in isolated guinea-pig papillary muscles. Membrane resting potential and action potential parameters were not significantly changed, while CL 86-02-01 exerted a concentration-dependent inotropic effect by increasing the maximum rate of force development and maximum rate of force relaxation. Time to peak force, relaxation time and total contraction time were reduced. These effects are similar to those of beta-adrenergic drugs and phosphodiesterase inhibitors, but markedly differ from those described for other positive inotropic agents like cardiac glycosides, calcium agonists, alpha-adrenergic drugs or increased extracellular calcium concentration.