Intercellular Ca2+ waves in rat hippocampal slice and dissociated glial-neuron cultures mediated by nitric oxide

Nitric oxide (NO) may participate in cell-cell communication in the brain by generating intercellular Ca2+ waves. In hippocampal organotypic and dissociated glial-neuron (> 80% glia) cultures local applications of aqueous NO induced slowly propagating intercellular Ca2+,waves, In glial cultures, Ca2+ waves and Mn2+ quench of cytosolic fura-a fluorescence mediated by NO were inhibited by nicardipine, indicating that NO induces Ca2+ influx in glia which is dihydropyridinesensitive. As NO treatments also depolarised the plasma membrane potential of glia, the nicardipine-sensitive Ca influx might be due to the activation of dihydropyridine-sensitive L-type Ca channels, Both nicardipine-sensitive intercellular Ca waves and propagating cell depolarisation induced by mechanical stress of individual glia were inhibited by pretreating cultures with either an NO scavenger or NG-methyl-L-arginine. Results demonstrate that NO can induce Ca2+ waves in hippocampal slice cultures, and that Ca2+ influx coupled to NO-mediated membrane depolarisation might assist in fashioning their spatiotemporal dynamics. (C) 2000 Federation of European Biochemical Societies, Published by Elsevier Science B.V. All rights reserved.