The distribution of P2X receptor clusters on individual neurons in sympathetic ganglia and their redistribution on agonist activation

Abstract

The distribution of P2X receptors on neurons in rat superior cervical ganglia and lability of P2X receptors on exposure to agonists were determined. Antibody labeling of each P2X subtype P2X1-P2X7 showed neurons isolated into culture possessed primarily P2X2 subunits with others occurring in order P2X7 > P2X6 > P2X3 > P2X1 > P2X5 > P2X4. Application of ATP and α,β-meATP to neurons showed they possessed a predominantly non-desensitizing P2X receptor type insensitive to α,β-meATP, consistent with immunohistochemical observations. P2X1-green fluorescent protein (GFP) was used to study the time course of P2X1 receptor clustering in plasma membranes of neurons and internalization of receptors following prolonged exposure to ATP. At 12-24 h after adenoviral infection, P2X1-GFP formed clusters about 1 μm diameter in the neuron membrane. Application of ATP and α,β-meATP showed these neurons possessed a predominantly desensitizing P2X receptor type sensitive to α,β-meATP. Infection converted the major functional P2X receptor type in the membrane to P2X1. Exposure of infected neurons to α,β-meATP for less than 60 s led to the disappearance of P2X1-GFP fluorescence from the cell surface that was blocked by monensin, indicating the chimera is normally endocytosed into these organelles on exposure to agonist.