Meningeal cells can communicate with astrocytes by calcium signaling

Mechanical stimulation of adult human and rat pia-arachnoid cell cultures ( loaded with calcium indicator dye) produced an increase in calcium in the s timulated cell. This change then propagated rapidly among neighboring cells , producing a calcium wave with a maximum distance of propagation and veloc ity resembling calcium waves in astrocytes. The pia-arachnoid waves were bl ocked by either octanol or apyrase, suggesting that propagation might occur either by gap junction communication or extracellular movement of ATP. Cal cium waves in pia-arachnoid cells could invade contiguous astrocytes, and v ice versa. Gap junction coupling between pia-arachnoid cells and astrocytes was shown by dye transfer experiments, in conjunction with immunostaining for connexin43, We infer that calcium signals from cells in the cortical pa renchyma may be transmitted to the pia-arachnoid and might then serve in th e induction of neurovascular changes, including those postulated to be resp onsible for the pain of migraine headache.