ISSN:
1471-4159
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Medicine
Notes:
The present study investigated the pharmacological properties of excitatory P2X receptors and P2X2 and P2X5 receptor subunit expression in rat-cultured thoracolumbar sympathetic neurons. In patch-clamp recordings, ATP (3–1000 µm; applied for 1 s) induced inward currents in a concentration-dependent manner. Pyridoxal-phosphate-6-azophenyl-2′,4′-disulfonate (PPADS; 30 µm) counteracted the ATP response. In contrast to ATP, α,β-meATP (30 µm; for 1 s) was virtually ineffective. Prolonged application of ATP (100 µm; 10 s) induced receptor desensitization in a significant proportion of sympathetic neurons in a manner typical for P2X2−2 splice variant-mediated responses. Using single-cell RT-PCR, P2X2, P2X2−2 and P2X5 mRNA expression was detectable in individual tyrosine hydroxylase-positive neurons; coexpression of both P2X2 isoforms was not observed. Laser scanning microscopy revealed both P2X2 and P2X5 immunoreactivity in virtually every TH-positive neuron. P2X2 immunoreactivity was largely distributed over the cell body, whereas P2X5 immunoreactivity was most distinctly located close to the nucleus. In summary, the present study demonstrates the expression of P2X2, P2X2−2 and P2X5 receptor subunits in rat thoracolumbar neurons. The functional data in conjunction with a preferential membranous localization of P2X2/P2X2−2 compared with P2X5 suggest that the excitatory P2X responses are mediated by P2X2 and P2X2−2 receptors. Apparently there exist two types of P2X2 receptor-bearing sympathetic neurons: one major population expressing the unspliced isoform and another minor population expressing the P2X2−2 splice variant.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1046/j.1471-4159.2001.00653.x
