P2Y receptors contribute to ATP-induced increases in intracellular calciumin differentiated but not undifferentiated PC12 cells

ATP-induced Ca2+ transients were examined in individual PC12 cells of a wel l defined clone, before and after treatment with nerve growth factor (NGF) to induce a neurone-like phenotype. Using reverse transcriptase PCR these c ells were found to express mRNA for several PZ receptors, In undifferentiat ed cells the ATP-induced Ca2+ response was entirely dependent on Ca2+ influ x, could nor be mimicked by UTP, alpha,beta-methylene ATP or dibenzoyl ATP or be blocked by pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (PPA DS). ATP had no significant effect on levels of cyclic AMP or inositol 1,4, 5-trisphosphate (InsP(3)). These results suggest that in undifferentiated P C12 cells ATP mainly acts on a P2X receptor, possibly the P2X(4) subtype, A fter treatment with NGF for 7 days the ATP response was increased and parti ally sensitive to PPADS, A component of the ATP-induced Ca2+ increase was d ue to mobilisation of intracellular Ca2+ stores and another to capacitative Ca2+ entry, UTP caused an increase in intracellular Ca2+, and InsP(3) form ation could be stimulated by ATP and UTP, ATP also caused a small increase in cyclic AMP, but this was abolished in the presence of indomethacin. Thus , after NGF treatment ATP acts partially via a P2Y receptor, possibly the P 2Y(2) subtype. (C) 2000 Elsevier Science Ltd. All rights reserved.