Fig. 6.
Model for the initiation and propagation of interneuronal calcium waves underlying neuronal domains. Waves are initiated either by ambient or synaptically released glutamate (Glu; open triangles) that acts on metabotropic glutamate receptors (mGluR). This stimulates the G-protein (G)-phospholipase C (PLC) cascade that results in the production of inositol trisphosphate (IP3; filled circles). IP3 activatesIP3 receptors (IP3R; small filled ovals) and thereby causes calcium release (filled squares) from intracellular stores. In addition,IP3 also diffuses through gap junctions (GJ) into neighboring neurons where it causes calcium release. In coupled cells, IP3 could be regenerated by calcium-mediated positive feedback loops (dashed arrows), including the sensitization ofIP3R and stimulation ofPLC.