Ionic mechanisms of a novel neurotoxin from the sea anemone Anthopleura sp.in rat ventricular myocytes

Journal of Southern Medical University ›› 2004, Vol. 24 ›› Issue (06): 609-613,618.

Ionic mechanisms of a novel neurotoxin from the sea anemone Anthopleura sp.in rat ventricular myocytes

OUYANG Ping¹, DENG Chun-yu², LIU Wen-hua³, WANG Lei³, LIANG Dong³, QIAN Wei-min², XU An-long³

1. 第一军医大学南方医院心血管内科, 广东, 广州, 510515;
2. 广东省人民医院电生理研究室, 广东, 广州, 510080;
3. 中山大学生命科学学院国家高技术发展计划海洋功能基因组开放实验室, 广东, 广州, 510275

Online:2004-06-20 Published:2004-06-20

Abstract

Abstract: Objective To determine the ionic mechanisms of a novel neurotoxin rhk2a obtained from the sea anemone Anthopleura sp.in rat ventricular myocytes. Methods Whole-cell patch-clamp recording technique was used to record the sodium, calcium, and sodium-calcium exchange currents (I_Na, I_Ca,L and I_Na-Ca, respectively) in the isolated single rat ventricular myocytes with or without rhk2a treatment. Results The current-voltage (I-V) relationship for whole-cell I_Na in the non-treated and rhk2a-treated (at the dose of 1 μmol/L) myocytes showed no significant difference (P>0.05), but the time constants for inactivation (τ_h) were significantly greater (P<0.05) for the treated cells over the entire course of the experiment, while the time constants for activation (τ_m) exhibited no significant difference between the two cells. The inactivation curve of I_Na of rhk2a-treated cells was similar to that of the non-treated cells, as with the I-V relationship for whole-cell L-type calcium current (I_Ca,L) and I_Na-Ca). Conclusions Delayed inactivation of Na⁺ channel plays an important role in the positive inotropic effect of rhk2a, possibly resulting from the alteration in Na⁺ channel kinetics induced by rhk2a. rhk2a does not directly affect I_Ca,L or I_Na-Ca.

CLC Number:

OUYANG Ping¹, DENG Chun-yu², LIU Wen-hua³, WANG Lei³, LIANG Dong³, QIAN Wei-min², XU An-long³. Ionic mechanisms of a novel neurotoxin from the sea anemone Anthopleura sp.in rat ventricular myocytes[J]. Journal of Southern Medical University, 2004, 24(06): 609-613,618.

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