[The modulation of anomalous automatism in ischemic Purkinje fibers by a specific subclass of alpha 1-adrenoblockers].
In the present study, the authors used two specific blockers of alpha 1-adrenergic receptor subtypes (chloroethyclonidine and WB-4101) to determine the mechanisms responsible for automatic rhythm occurring during simulated ischemia and reperfusion of isolated canine Purkinje fibers. In the control situation, all fibers showed membrane potentials greater than -90 mV and normal automatic rhythm. During simulated ischemia, the membrane potential depolarized to the -60 mV range. Abnormal automaticity was seen in 20% of fibers untreated with phenylephrine and in 50% of those supervised with 10(-7) M phenylephrine. The incidence of abnormal automaticity was reduced to 0% with WB-4101 and increased to 90% with chloroethylclonidine. Moreover, the ischemic fibers were significantly more hyperpolarized during superfusion with WB-4101 than with chloroethylclonidine. It is concluded that automatic arrhythmias induced by alpha 1-adrenergic stimulation during simulated ischemia may be attributed to a specific alpha 1-adrenergic receptor subtype that is blocked by WB-4101.
Aniukhovskiĭ
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EP
Rosen
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MR
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000704:Analysis of Variance; D000818:Animals; D001145:Arrhythmias, Cardiac / Q000453:epidemiology / Q000209:etiology / Q000503:physiopathology; D003000:Clonidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D004146:Dioxanes / Q000494:pharmacology*; D004285:Dogs; D006339:Heart Rate / Q000187:drug effects* / Q000502:physiology; D066298:In Vitro Techniques; D017202:Myocardial Ischemia / Q000150:complications / Q000453:epidemiology / Q000503:physiopathology*; D015425:Myocardial Reperfusion / Q000379:methods; D010477:Perfusion / Q000379:methods; D011690:Purkinje Fibers / Q000187:drug effects* / Q000502:physiology; D018340:Receptors, Adrenergic, alpha-1 / Q000187:drug effects / Q000502:physiology
D000317:Adrenergic alpha-Antagonists; D004146:Dioxanes; D018340:Receptors, Adrenergic, alpha-1; C051731:chlorethylclonidine; C010654:(2-(2',6'-dimethoxy)phenoxyethylamino)methylbenzo-1,4-dioxane; D003000:Clonidine
Moduliatsiia spetsificheskim podklassom al'fa 1-adrenoblokatorov anomal'noĭ avtomatii v ishemizirovannykh voloknakh Purkin'e.