Effect of sulfhydryl oxidation on ionic and gating currents associated with L-type calcium channels in isolated guinea-pig ventricular myocytes

• Published in: Cardiovascular research 1995-11, Vol.30 (5), p.799-806
• Main Authors: Lacampagne, Alain, Duittoz, Anne, Bolaños, Pura, Peineau, Nicolas, Argibay, Jorge A.
• Format: Article
• Language: English
• Subjects: Calcium channel; Guinea pig; L-type; Sulfhydryl groups; ventricular myocytes
• ISSN: 0008-6363; 1755-3245
• DOI: 10.1016/S0008-6363(95)00128-X

Objective: L-type calcium currents (Ica) and gating currents modification by extracellular application of the selective free sulfhydryl oxidant p-hydroxy-mercuric-phenylsulphonic acid (PHMPS) were studied. Methods: Both currents were obtained with the whole cell patch clamp technique in guinea-pig ventricular cardiocytes. Results: The main finding was a reduction of Ica clearly differentiable from a “run down” process. This effect was protected, stopped and in some cases partially reversed by dithiothreitol, a protective reagent for -SH groups. We also found a decrease of the gating currents associated with L-type calcium channels. The calcium modulation and cAMP phosphorylation systems of Ica are unaffected by PHMPS. With barium as charge carrier the current-voltage curves of barium currents were shifted by 10 mV to the positive direction by PHMPS. The same effect was obtained with calcium currents using BAPTA as a fast calcium buffer. Conclusion: The results indicate that oxidation of -SH groups carried by the channel protein induces dysfunction of the calcium entry to cardiac cells by altering the gating process. A participation of thiol functions on the gating of the calcium channel is proposed.