Changes in intracellular Ca2+ by activation of P2 receptors in submucosal neurons in short-term cultures

Electrophysiological and Ca2+ microfluorimetric techniques were used to cha racterize the pharmacological profile of the P2 receptors expressed in subm ucosal neurons and the changes in intracellular Ca2+ associated with activa tion of these receptors. ATP caused a fast and slow membrane depolarization s during intracellular recordings. ATP induced a rapid inward current durin g whole-cell experiments. Receptors mediating the inward current and fast d epolarization have the same pharmacological profile and these ATP responses were more sensitive to pyridoxalphosphate-6-azophenyl-2',4'-disulfonic aci d than Basilen BlueE-3G, and potentiated by suramin. The slow depolarizatio n was not blocked by these P2 receptor antagonist, pertussis toxin, or KT57 20 (protein kinase A inhibitor). N-ethylmaleimide or protein kinase C inhib itors (staurosporine and calphostin) blocked this depolarization. ATP induc ed complex multi-phasic Ca2+ transients in most neurons, classified as fast , slow, or mixed fast/slow responses. In conclusion, the fast and slow Ca2 responses were mediated by respective activation of P2X and P2Y receptors and were associated with fast and slow depolarizations, respectively. (C) 2 000 Elsevier Science B.V. All rights reserved.