Short- and long-term roles of phosphatidylinositol 4,5-bisphosphate PIP2 on Cav3.1- and Cav3.2-T-type calcium channel current |
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Authors: | Yangong Liu Tomohiro Iwano Fangfang Ma Pu Wang Yan Wang Mingqi Zheng Gang Liu Katsushige Ono |
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Institution: | 1. Department of Cardiology, The First Hospital of Hebei Medical University, 89 Donggang Road, Shijiazhuang, Hebei Province, 050031, People’s Republic of China;2. Department of Pathophysiology, Oita University School of Medicine, Yufu, Oita, 879-5593, Japan |
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Abstract: | T-type calcium (Ca2+) channels play important physiological functions in excitable cells including cardiomyocyte. Phosphatidylinositol-4,5-bisphosphate (PIP2) has recently been reported to modulate various ion channels’ function. However the actions of PIP2 on the T-type Ca2+ channel remain unclear. To elucidate possible effects of PIP2 on the T-type Ca2+ channel, we applied patch clamp method to investigate recombinant CaV3.1- and CaV3.2-T-type Ca2+ channels expressed in mammalian cell lines with PIP2 in acute- and long-term potentiation. Short- and long-term potentiation of PIP2 shifted the activation and the steady-state inactivation curve toward the hyperpolarization direction of CaV3.1-ICa.T without affecting the maximum inward current density. Short- and long-term potentiation of PIP2 also shifted the activation curve toward the hyperpolarization direction of CaV3.2-ICa.T without affecting the maximum inward current density. Conversely, long-term but not short-term potentiation of PIP2 shifted the steady-state inactivation curve toward the hyperpolarization direction of CaV3.2-ICa.T. Long-term but not short-term potentiation of PIP2 blunted the voltage-dependency of current decay CaV3.1-ICa.T. PIP2 modulates CaV3.1- and CaV3.2-ICa.T not by their current density but by their channel gating properties possibly through its membrane-delimited actions. |
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Keywords: | Phosphatidylinositol-4 T-type calcium channel Corresponding author at: Department of Pathophysiology Oita University School of Medicine 1-1 Idaigaoka Hasama Yufu Oita 879-5593 Japan |
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