Knockout of ClCª²3 fails to change PKCª²sensitivity of swellingª²activated chloride channel in cardiomyocytes

    GONG Weiª²Qin, ZANG Yiª²Min, WANG Xiaoª²Ming, LI Yuan, Takahiro SHIMIZU, Yasunobu OKADA

    1Department of Geriatrics, Xijing Hospital, 2Department of Physiology, School of Basic Medicine, Fourth Military Medical University, Xi¡¯an 710033, China, 3Department of Cell Physiology, National Institute for Physiological Sciences, Okazaki 444ª²8585, Japan

    ¡¾Abstract¡¿ AIM: To find out whether ClCª²3 can influence PKCª²sensitivity of swellingª²activated chloride (VSOR Cl-) channel in mouse ventricular myocytes. METHODS: Mice with homozygous disruption of Clcn3 gene (Clcn3-/- mice) were produced by techniques of gene targeting, RTª²PCR and patch clamp whole cell recording, the expression of ClCª²3 mRNA was detected and VSOR Cl- currents were measured. RESULTS: ¢ÙVSOR Cl- currents were significantly augmented by application of 1 ¦Ìmol/L phorbol 12ª²myristate 13ª²acetate (PMA) under hypotonic condition. ¢ÚPMA application under isotonic conditions did not produce significant effects on the basal currents. The time course of swellingª²induced current activation in PMAª²pretreated cells was much faster than that in cells without PMAª²pretreatment. ¢Û The increase effects of PMA on VSOR Cl- currents were not significantly different between wild type and Clcn3-/- mice. ¢Ü10 ¦Ìmol/L chelerythrine (CHE)ª²pretreatment almost completely abolished the activation of VSOR Cl- currents induced by osmotic swelling and the upª²regulatory effects of PMAª²posttreatment on VSOR Cl- channel. CONCLUSION: The activation mechanism of VSOR Cl- channel in mouse ventricular myocytes is almost totally dependent on the PKC activity. The PKC dependence of VSOR Cl- channel is not affected by the molecular expression of ClCª²3. ......