Abstract: Objective To investigate the effect of Ca2+ influx through L-type Ca2+ channels on normal and hyperpolarized membrane potential of arteriole smooth muscle cells (ASMCs) in rats. Methods The ASMCs isolated from normal rats and those with severe hemorrhagic shock were labeled with DiBAC4 (3) for membrane potential detection. Results Ca2+ influx caused hyperpolarization of the membrane potential in the normal ASMCs but depolarization in the cells from rats with hemorrhagic shock, and this effect could be inhibited by TEA. Conclusion Ca2+-activated potassium channels activated by Ca2+ influx through L-type Ca2+ channels in normal ASMCs to cause hyperpolarization but leads directly to membrane potential depolarization in ASMCs from rats with severe hemorrhagic shock. This finding can be meaningful for treatment of vascular hyporeactivity in advanced stage of severe shock.