(Experimental study on cellular electrophysiology of Viscum coloratumflavonoid in treating tachyarrhythmias).

Journal/Book: Chung-Kuo-Chung-Hsi-I-Chieh-Ho-Tsa-Chih 1994 Jul, VOL: 14 (7), P: 421-3,ISSN: 1003-5370.. 1995;

Abstract: Viscum Coloratum Flavonoid (VCF) is one of the dihydro-flavonoidsisolated and purified from the stem and leaf of Viscum Coloratum. It wasproved both experimentally and clinically to have the effects ofanti-tachyarrhythmias. The mechanism of this effect, however, wasunclear. In this study, the effects of the drug on the fast responseaction potentials (FAP) in canine Purkinje fibers and guinea pigventricular myocardial cells were investigated by glass-microelectrodetechnique. The results indicated that 0.1 mg/ml VCF accelerated therepolarizations of 2nd and 3rd phase of FAP, shortened action potentialduration (APD), and slightly shortened effective refractory period (ERP)(canine) or unchanged (guinea pig). delta ERP/delta APD ratio wasincreased, therefore, ERP was relatively prolonged. All effects appearedafter using the drug for 2 minutes, reached stable status after 10minutes, and disappeared after washing off the drug for 15 minutes. Itwas suggested that VCF was the drug which exerted effects rapidly,maintained effects shortly, and had effects reversibly. The cellularelectrophysiologic mechanisms of VCF on anti-tachyarrhythmias should beattributed to prolong the ERP relatively and abolish the reentry. Thisdrug is particularly applicable to the tachyarrhythmias due to reentry.Author.

Keyword(s): ACTION-POTENTIALS/DE (drug effects)

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