Rapid downregulation of NCX and PMCA in hippocampal neurons following H2O2 oxidative stress.

Na+/Ca2+ exchangers (NCXs) and plasma membrane Ca2+ pumps (PMCAs) are crucial for intracellular Ca2+ homeostasis and Ca2+ signaling. Elevated [Ca2+]i is a hallmark of neurodegenerative disease and stroke. Here we studied the short-term effect of oxidative stress on the plasma membrane Ca2+ extrusion systems in hippocampal neurons (HN) and found that after 2-3 h exposure to 300 microM H2O2, all NCXs and PMCAs were significantly downregulated at the RNA (NCX) and protein (PMCA) level. Rapid internalization and aggregation of the PMCA was also observed. Our data show that the plasma membrane calcium extrusion systems are sensitive early targets of neurotoxic oxidative stress.