P2Y1 Receptor Activation Enhances the Rate of Rat Pinealocyte-Induced Extracellular Acidification via a Calcium-Dependent Mechanism

Pineal gland G-protein coupled P2Y1 receptors potentiate noradrenaline-induced N′-acetylserotonin production, a long term response which occurs after 5 h incubation. In the current study we show that a short-term effect of stimulation of P2Y1 receptors is the increase in extracellular acidification rate (ECAR), which is mediated by an increase in intracellular calcium concentration ([Ca2+]i). The pD2 values for ATP (3.06 ± 0.12)-induced ECAR increase was significantly smaller (p 1 receptor antagonists A3′P-5′P and A3′P-5′PS inhibited the increase in ECAR-induced by ADP. Clamping [Ca2+]i with BAPTA (30 and 50 µmol/l) led to inhibition of ADP-induced increase in ECAR. Agonist and antagonist data indicate P2Y1 activation leads to a [Ca2+]i-dependent acidification of the extracellular medium.