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Effect of a new adrenergic beta receptor blocker ACC-9089 on transmembrane potential of canine Purkinje fibers in comparison with propranolol

Authors: Yue-hua Tan, Andrew L Wit


ACC 0.1 mg/L and propranolol, which did not cause any changes in the trans membrane potential, diminished or eliminated the increases in diastolic depolarization and the spontaneous firing rate induced by epinephrine. Resting membrane potential increased in ACC 0.3 mg/L but was unchanged in higher concentrations. Propranolol up to 10 mg/L had no effect on resting potential. The voltage time course of repolarization was unaffected by ACC in 0.3-10 mg/L, yet markedly shortened by propranolol. ERP markedly decreased in propranolol 3 mg/L, but was unchanged in ACC 3 mg/L and slightly decreased in ACC 10 mg/L.Only in 10 mg/L did ACC decrease Vmax, overshoot and APA.These direct effects of ACC 10 mg/L were much less than those of propranolol 3 mg/L. It is concluded that ACC is a potent beta –receptor blocker with only slight direct membrane depressant effects.

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