Expression of P2X(2) and P2X (3) receptors in the rat carotid sinus, aortic arch, vena cava, and heart, as well as petrosal and nodose ganglia.

With single- and double-labeling immunofluorescence techniques, the distribution patterns and morphological characteristics of P2X(2)- and P2X(3)-immunoreactive nerve fiber terminals and neuronal bodies have been studied in the main circulatory system baroreceptors and the nodose and petrosal ganglia of rats. A high density of P2X(2)- and P2X(3)-immunoreactive nerve fiber terminals was detected in the carotid sinus. P2X(2)- and P2X(3)-immunoreactive nerve fiber terminals were also distributed widely in the aortic arch, atrium, vena cava, and ventricles. Almost all the P2X(2)-immunoreactive nerve fiber terminals were immunoreactive for P2X(3) receptors. P2X(2)- and P2X(3)-immunoreactive neuronal bodies were also detected in the nodose and petrosal ganglia, which are the sources of the P2X(2)- and P2X(3)-immunoreactive nerve terminals. P2X(2) and P2X(3) receptors were expressed in the same ganglionic neurons. These data indicate that extracellular ATP, via the homomeric P2X(2) and P2X(3) receptors, and heteromeric P2X(2/3) receptor in the sensory receptors of carotid sinus, aortic arch, atrium, and vena cava, may be involved in the regulation of systematic circulation blood pressure.