Effects of Goniopora toxin on the membrane currents of bullfrog atrial muscle

Mami Noda, Ikunobu Muramatsu, Motohatsu Fujiwara

研究成果: Contribution to journalArticle査読

7 被引用数 (Scopus)


The effects of Goniopora toxin (GPT), isolated from the Goniopora species, on the action potential and membrane currents of bullfrog atrial muscle were studied using the double sucrose-gap method. GPT at concentrations above 10 nmol/l prolonged the duration of the action potential and sometimes induced arrhythmias. The prolongation was also induced in the presence of Ca channel blockers (Mn or verapamil). These effects were not reversed by continuous superfusion of GPT-free solution, but were rapidly antagonized by tetrodotoxin (1 μmol/l). The resting potential was not affected by GPT. Voltage clamp experiments revealed that sustained inward current flows following the fast sodium current upon depolarization, in the presence of GPT. The current was elicited by the toxin in Mn-treated fibers and abolished in the presence of TTX. The delayed outward current (Ix) was slightly reduced; the background K current (IK1), inward background current (Ib) and slow inward current (Islow) were not altered by GPT. These results suggest that GPT acts on sodium channels to give rise to a prolonged sodium current which is in turn responsible for the prolongation of the action potential.

ジャーナルNaunyn-Schmiedeberg's Archives of Pharmacology
出版ステータス出版済み - 3 1 1984

All Science Journal Classification (ASJC) codes

  • Pharmacology

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