title: Effect of yohimbine on action potentials recorded from isolated canine ventricular myocytes.
abstract: Yohimbine is used extensively as an alpha 2-adrenoceptor antagonist. This drug also inhibits sodium channels in the squid axon. In this study we investigated the electrophysiological effects of yohimbine in isolated canine ventricular myocytes. Yohimbine produced a reversible and concentration-dependent decrease in the maximum upstroke velocity and a slight increase in the action potential duration. The maximum upstroke velocity was reduced by over 90% by 10(-4) M yohimbine. It did not effect the resting or plateau potentials in control or isoproterenol-treated cells. Delayed after-depolarizations were also inhibited. These data suggest that yohimbine can produce a local anesthetic effect which is primarily due to inhibition of sodium channels.
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D004285:Dogs; D006321:Heart / Q000187:drug effects* / Q000502:physiology; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects; D007545:Isoproterenol / Q000494:pharmacology; D009206:Myocardium / Q000166:cytology; D012964:Sodium / Q000378:metabolism; D015016:Yohimbine / Q000494:pharmacology*
chemical_list: D007473:Ion Channels; D015016:Yohimbine; D012964:Sodium; D007545:Isoproterenol