Résumé
The effects of extracellular ATP on phosphoinositide metabolism and intracellular Ca
2+ concentration were studied in a primary culture of rat aortic myocytes. ATP increases the level of inositol phosphates, the putative second messenger for Ca
2+ mobilization. No saturation of inositol phosphates accumulation is obtained (up to 10
−2M ATP). Under the same conditions, ATP rapidly mobilizes intracellular Ca
2+ in fura-2 loaded myocytes. The mobilization of intracellular Ca
2+ is dose-dependent (maximal at 10
−4M ATP), and is not affected by addition of EGTA. It is concluded that the receptors mediating the cytosolic increase of Ca
2+ are of the P
2-purinoceptor subtype. The physiological functions of these receptors are not presently known.