AGING ENHANCES THE CALCIUM SENSITIVITY OF CENTRAL NEURONS OF THE MOUSE AS AN ADAPTIVE RESPONSE TO REDUCED FREE INTRACELLULAR CALCIUM

Age-related changes in Ca2+-homeostasis have been investigated in mechanically dissociated neurons from young and aged mice. In aged animals, basal intracellular calcium ([Ca2+]i) was significantly reduced and depolarization (KCl)-induced rise in [Ca2+]i was lower, probably as a result of increased activation of Ca2+-dependent mechanisms terminating Ca2+ influx. Additionally, depolarization-induced inositolphosphate (IP) accumulation in aged animals was found to be significantly increased. Both findings suggest that Ca2+-dependent intracellular processes become more sensitive to Ca2+ in aged animals due to decreased Ca2+ availability.