Involvement of veratridine-induced increase of reverse Na(+)/Ca(2+) exchange current in intracellular Ca(2+) overload and extension of action potential duration in rabbit ventricular myocytes

• Published in: Sheng li hsüeh pao Vol. 64; no. 4; p. 433
• Main Authors: Kong, Ling-Hao, Ma, Ji-Hua, Zhang, Pei-Hua, Luo, An-Tao, Zhang, Shuo, Ren, Zhi-Qiang, Feng, Juan, Chen, Jiu-Ling
• Format: Journal Article
• Language: Chinese
• Published: China 25.08.2012
• Subjects: Acetanilides - pharmacology; Action Potentials; Animals; Calcium - metabolism; Myocardial Contraction; Myocytes, Cardiac - cytology; Myocytes, Cardiac - drug effects; Patch-Clamp Techniques; Piperazines - pharmacology; Rabbits; Ranolazine; Sodium-Calcium Exchanger - metabolism; Tetrodotoxin - pharmacology; Veratridine - pharmacology
• ISSN: 0371-0874

The objectives of this study were to investigate the effects of veratridine (VER) on persistent sodium current (I(Na.P)), Na(+)/Ca(2+) exchange current (I(NCX)), calcium transients and the action potential (AP) in rabbit ventricular myocytes, and to explore the mechanism in intracellular calcium overload and myocardial contraction enhancement by using whole-cell patch clamp recording technique, visual motion edge detection system, intracellular calcium measurement system and multi-channel physiological signal acquisition and processing system. The results showed that I(Na.P) and reverse I(NCX) in ventricular myocytes were obviously increased after giving 10, 20 μmol/L VER, with the current density of I(Na.P) increasing from (-0.22 ± 0.12) to (-0.61 ± 0.13) and (-2.15 ± 0.14) pA/pF (P < 0.01, n = 10) at -20 mV, and that of reverse I(NCX) increasing from (1.62 ± 0.12) to (2.19 ± 0.09) and (2.58 ± 0.11) pA/pF (P < 0.05, n = 10) at +50 mV. After adding 4 μmol/L tetrodotoxin (TTX), current density of I(Na.P) and r