Figure 2.

Desensitization of purinergic receptors inhibits the extent of calcium signaling in cultured astrocytes. First row shows mechanical-induced astrocytic calcium wave (white arrow). Sequence of images (1, 7, 15 sec after stimulation) depicts a typical calcium wave under control conditions. Second row shows the same field of astrocytes mobilize Ca²⁺i transiently in response to 2MeSATP (10 μM). Third row shows mechanical stimulation of a cell neighboring the cell stimulated in the first block (white arrow) failed to induce a propagating Ca²⁺ wave after exposure to 2MeSATP. Ca²⁺i increases are limited to a few cells surrounding the stimulated cell. Stimulation was performed when Ca²⁺i had returned to resting level after the exposure to 2MeSATP (5–10 min). Wave radius was on an average reduced to 11 ± 8 (n = 8) after exposure to 2MeSATP. Fourth row shows subsequent challenge with bradykinin (25 μM) demonstrating that intracellular calcium stores were not depleted by 2MeSATP exposure and that the cells remained viable.