ATP and adenosine trigger the interaction of plasma membrane IP 3 receptors with protein kinase A in oviductal ciliated cells

Abstract

We have demonstrated that adenosine did not produce any change of intracellular free Ca 2+ concentration ([Ca 2+]i) in oviductal ciliated cells; however, it increased the ATP-induced Ca 2+ influx through the activation of protein kinase A (PKA). Uncaging of IP 3 and cAMP triggered a larger Ca 2+ influx than did IP 3 alone. Furthermore, the IP 3 effect was abolished by Xestospongin C, an IP 3 receptor blocker. Whole-cell recordings demonstrated the presence of an ATP-induced Ca 2+ current, and the addition of adenosine increased the peak of this current. This effect was not observed in the presence of H-89, a PKA inhibitor. Using excised macro-patches of plasma membrane, IP 3 generated a current, which was higher in the presence of the catalytic PKA subunit and this current was blocked by Xestospongin C. We show here that activation of plasma membrane IP 3 receptors directly triggers Ca 2+ influx in response to ATP and that these receptors are modulated by adenosine-activated PKA.