[The modulation of anomalous automatism in ischemic Purkinje fibers by a specific subclass of alpha 1-adrenoblockers].

Abstract

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.

• Authors: E P Aniukhovskiĭ, M R Rosen
• Journal: Kardiologiia (Kardiologiia) Vol. 33 Issue 9 Pg. 47-51, 5 ( 1993) ISSN: 0022-9040 [Print] Russia (Federation)
• Vernacular Title: Moduliatsiia spetsificheskim podklassom al'fa 1-adrenoblokatorov anomal'noĭ avtomatii v ishemizirovannykh voloknakh Purkin'e.
• PMID: 7908348 (Publication Type: Comparative Study, Journal Article)

Chemical References

• Adrenergic alpha-Antagonists
• Dioxanes
• Receptors, Adrenergic, alpha-1
• chlorethylclonidine
• (2-(2',6'-dimethoxy)phenoxyethylamino)methylbenzo-1,4-dioxane
• Clonidine

Topics

• Action Potentials (drug effects, physiology)
• Adrenergic alpha-Antagonists (pharmacology)
• Analysis of Variance
• Animals
• Arrhythmias, Cardiac (epidemiology, etiology, physiopathology)
• Clonidine (analogs & derivatives, pharmacology)
• Dioxanes (pharmacology)
• Dogs
• Heart Rate (drug effects, physiology)
• In Vitro Techniques
• Myocardial Ischemia (complications, epidemiology, physiopathology)
• Myocardial Reperfusion (methods)
• Perfusion (methods)
• Purkinje Fibers (drug effects, physiology)
• Receptors, Adrenergic, alpha-1 (drug effects, physiology)