Secretion and hydrolysis of ATP by Ehrlich ascites tumor cells during centrifugation. Dependence on calcium and temperature

Precipitation of Ehrlich ascites tumor cells (EATC) by centrifugation causes ATP secretion. ATP secretion is accompanied by an increase of calcium concentration in the cytosol and persists for a long time (minutes) after centrifugation during the storage of cells at a low temperature. During prolonged storage (for more than 1.5 h), the concentration of extracellular ATP decreases to the level of ∼100 nM due to termination of secretion and ATP hydrolysis by surface ATPases. The rate of ATP hydrolysis exponentially falls with the temperature decrease from 36 to 8°C. ARL67156, a selective inhibitor of E-NTPDase-1, effectively suppresses the extracellular ATP hydrolysis. The intensity of ATP secretion does not correlate with the calcium ions concentration in the cytosol and Ca²⁺ mobilization from endoplasmic reticulum but correlates with the intensity of Ca²⁺ influx into the cells. The temperature dependences of ATP secretion intensity and Ca²⁺ entry rate coincide.