Differential regulation of L-type Ca2+ channels in cerebral and mesenteric arteries after simulated microgravity in rats and its intervention by standing

This study was designed to clarify whether simulated microgravity can induce differential changes in the current and protein expression of the L-type Ca2+ channel (CaL) in cerebral and mesenteric arteries and whether these changes can be prevented by daily short-duration −Gx exposure. Tail suspension [hindlimb unloading (HU)] for 3 and 28 days was used to simulate short- and medium-term microgravity-induced deconditioning effects. Standing (STD) for 1 h/day was used to provide −Gx as a countermeasure. Whole cell patch-clamp experiments revealed an increase in current density of CaL of vascular smooth muscle cells (VSMCs) isolated from cerebral arteries of rats subjected to HU and a decrease in VSMCs from mesenteric arteries. Western blot analysis revealed a significant increase and decrease of CaL channel protein expression in cerebral and small mesenteric arterial VSMCs, respectively, only after 28 days of HU. STD for 1 h/day did not prevent the increase of CaL current density in cerebral arterial VSMCs,...