Quantitative analysis of depolarization-induced ATP release from mouse brain synaptosomes: external calcium dependent and independent processes.

摘要: We and others have shown previously that ATP is secreted from mouse brain synaptosomes following depolarization of the membrane by high [K+]o time course can be monitored accurately measuring light emitted luciferin-luciferase included in reaction medium. In present work we evaluated relative importance [Ca2+]o potential on secretion process modelling release under different conditions. After correction records for destruction released synaptosomal ecto-ATPase activity, found occurs an apparent first order process. also established that, addition to classical [Ca2+]o-dependent mode, occurred absence extracellular calcium ([Ca2+]o less than 1 microM). Upon lowering Ca2+ concentration, both rate extent decreased. To assess contribution measured at potentials determined (or [Rb+]o) as defined distribution carbocyanine dye, diSC3(5). Rate constants computed curves revealed this parameter was essentially independent [Ca2+]o. Noise analysis signal showed variance increased upon stimulation [K+]o, suggesting modes are quantal. Thus, conclude nerve terminals depends entry but not potential, per se.