Serotonin-induced activation of TRPV4-like current in rat intrapulmonary arterial smooth muscle cells.
In the present study, we investigated the implication of transient receptor potential vanilloid (TRPV)-related channels in the 5-hydroxytryptamine (5-HT)-induced both intracellular calcium response and mitogenic effect in rat pulmonary arterial smooth muscle cells (PASMC). Using microspectrofluorimetry (indo-1 as Ca(2+) fluorescent probe) and the patch-clamp technique (in whole-cell configuration), we found that 5-HT (10 microM) induced a transient intracellular calcium mobilization followed by a sustained calcium entry. This latter was partly blocked by an inhibitor of cytochrome P450 epoxygenase (17-ODYA) and insensitive to cyclo-oxygenase and lipoxygenase inhibitors (indomethacin and CDC), suggesting the involvement of arachidonic acid metabolization by cytochrome P450 epoxygenase. This calcium influx was also sensitive to Ni(2+) and to ruthenium red, a TRPV channel blocker, and mimicked by 4alpha-phorbol-12,13-didecanoate (4alpha-PDD), a TRPV4 channel agonist. In patched PASMC, 5-HT and 4alpha-PDD-activated TRPV4-like ruthenium red sensitive currents with typical characteristics. Furthermore, 5-HT induced a ruthenium red sensitive increase in BrdU incorporation levels in PASMC. The present study provides evidence that 5-HT activates a TRPV4-like current, potentially involved in PASMC proliferation. The signalling pathway between proliferation and ion channel activation remains to be determined and may represent a molecular target for the treatment of vascular diseases such as pulmonary hypertension.
Université Bordeaux 2, Laboratoire de Physiologie Cellulaire Respiratoire, 146 rue Léo-Saignat, F-33076 Bordeaux, France. thomas.ducret@u-bordeaux.2.fr
Thomas
T
Ducret
Christelle
C
Guibert
Roger
R
Marthan
Jean-Pierre
JP
Savineau
D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000166:cytology*; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D011651:Pulmonary Artery / Q000033:anatomy & histology*; D051381:Rats; D017208:Rats, Wistar; D012701:Serotonin / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D050916:TRPV Cation Channels / Q000235:genetics / Q000378:metabolism*
D050916:TRPV Cation Channels; C486577:Trpv4 protein, rat; D016718:Arachidonic Acid; D012701:Serotonin; D002118:Calcium