The distribution of P2X receptor clusters on individual neurons in sympathetic ganglia and their redistribution on agonist activation.
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 P2X(1)-P2X(7) showed neurons isolated into culture possessed primarily P2X(2) subunits with others occurring in order P2X(7) > P2X(6) > P2X(3) > P2X(1) > P2X(5) > P2X(4). Application of ATP and alpha,beta-meATP to neurons showed they possessed a predominantly nondesensitizing P2X receptor type insensitive to alpha,beta-meATP, consistent with immunohistochemical observations. P2X(1)-green fluorescent protein (GFP) was used to study the time course of P2X(1) receptor clustering in plasma membranes of neurons and internalization of receptors following prolonged exposure to ATP. At 12-24 h after adenoviral infection, P2X(1)-GFP formed clusters about 1 microm diameter in the neuron membrane. Application of ATP and alpha,beta-meATP showed these neurons possessed a predominantly desensitizing P2X receptor type sensitive to alpha,beta-meATP. Infection converted the major functional P2X receptor type in the membrane to P2X(1). Exposure of infected neurons to alpha,beta-meATP for less than 60 s led to the disappearance of P2X(1)-GFP fluorescence from the cell surface that was blocked by monensin, indicating the chimera is normally endocytosed into these organelles on exposure to agonist.