Acetylcholine–induced calcium oscillation in isolated outer hair cells in guinea pig

ObjectiveThis study is to explore the relationship between acetylcholine (ACh)-induced calcium release from intracellular Ca2 + stores and function of outer hair cell(OHC) motors, in an attempt to elucidate the mechanism of OHC electromotility at resting state.MethodsOHCs were isolated from adult guinea pig (200-300 g) cochlea and loaded with Fluo-3/AM. The cells were treated with ACh/dHBSS, ACh/HBSS, dHBSS only or HBSS only. Intracellular [Ca2+ ]i variations in cells under the four treatments were observed using an Ar-Kr laser scan confocal microscope.ResultsCa2+ ]i oscillations were recorded in five OHCs treated with ACh/dHBSS but not in other cells. This is the first time that Ach-excited [Ca2+ i oscillations are reported in guinea pig OHCs independent of extracellular calcium.ConclusionsACh-excited [Ca2+ ]i oscillations in OHCs originates from intracellular calcium release and may play a crucial role in maintaining active mechanical motility of the OHC at resting and modulating OHC electromotility.