Premium
P2X 2 , P2X 2–2 and P2X 5 receptor subunit expression and function in rat thoracolumbar sympathetic neurons
Author(s) -
Schädlich H.,
Wirkner K.,
Franke H.,
Bauer S.,
Grosche J.,
Burnstock G.,
Reichenbach A.,
Illes P.,
Allgaier C.
Publication year - 2001
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.2001.00653.x
Subject(s) - ppads , receptor , excitatory postsynaptic potential , medicine , patch clamp , p2 receptor , endocrinology , biology , purinergic receptor , neuroscience , population , neuron , environmental health
The present study investigated the pharmacological properties of excitatory P2X receptors and P2X 2 and P2X 5 receptor subunit expression in rat‐cultured thoracolumbar sympathetic neurons. In patch‐clamp recordings, ATP (3–1000 µ m ; applied for 1 s) induced inward currents in a concentration‐dependent manner. Pyridoxal‐phosphate‐6‐azophenyl‐2′,4′‐disulfonate (PPADS; 30 µ m ) counteracted the ATP response. In contrast to ATP, α,β‐meATP (30 µ m ; for 1 s) was virtually ineffective. Prolonged application of ATP (100 µ m ; 10 s) induced receptor desensitization in a significant proportion of sympathetic neurons in a manner typical for P2X 2−2 splice variant‐mediated responses. Using single‐cell RT‐PCR, P2X 2 , P2X 2−2 and P2X 5 mRNA expression was detectable in individual tyrosine hydroxylase‐positive neurons; coexpression of both P2X 2 isoforms was not observed. Laser scanning microscopy revealed both P2X 2 and P2X 5 immunoreactivity in virtually every TH‐positive neuron. P2X 2 immunoreactivity was largely distributed over the cell body, whereas P2X 5 immunoreactivity was most distinctly located close to the nucleus. In summary, the present study demonstrates the expression of P2X 2 , P2X 2−2 and P2X 5 receptor subunits in rat thoracolumbar neurons. The functional data in conjunction with a preferential membranous localization of P2X 2 /P2X 2−2 compared with P2X 5 suggest that the excitatory P2X responses are mediated by P2X 2 and P2X 2−2 receptors. Apparently there exist two types of P2X 2 receptor‐bearing sympathetic neurons: one major population expressing the unspliced isoform and another minor population expressing the P2X 2−2 splice variant.