TRPV4-like non-selective cation currents in cultured aortic myocytes.
In this study, we provide evidence of critical changes in the expression of non-selective cation currents (NSCC) during culture in rat aortic myocytes. A selective TRPV4 agonist, 4alpha-phorbol 12,13-didecanoate (4alphaPDD), had little effect on membrane currents and intracellular Ca(2+) (Ca(2+)(i)) in freshly isolated cells from the aorta. In contrast, in cultured aortic myocytes with and without serum, 4alphaPDD at a concentration range between 0.3 and 3 muM effectively elevated Ca(2+)(i), which was abolished in the absence of external Ca(2+). Application of 4alphaPDD to cultured aortic myocytes also activated NSCC, which had a reversal potential of +3 mV. Both of these signals were blocked by ruthenium red (RuR), an effective blocker of TRPVs. Although the expression of TRPV4 mRNA transcript was found in cultured as well as non-cultured aortic myocytes, significant immunoreactivity to TRPV4 protein was only detected in cultured rat aortic myocytes. Moreover, cultured human pulmonary arterial smooth muscle cells (hPASM) had a substantial response to 4alphaPDD, which was susceptible to the removal of external Ca(2+) and application of RuR. These results provide a strong basis for our proposal that endogenous TRPV4 functions as an important regulator of Ca(2+)(i) in vascular myocytes under some physiological and pathophysiological conditions.
Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabedori, Mizuhoku, Nagoya, Japan.
Ryoichi
R
Tanaka
Katsuhiko
K
Muraki
Susumu
S
Ohya
Hisao
H
Yamamura
Noriyuki
N
Hatano
Yuka
Y
Itoh
Yuji
Y
Imaizumi
D000818:Animals; D001011:Aorta / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D006801:Humans; D008297:Male; D008564:Membrane Potentials; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000378:metabolism*; D010703:Phorbol Esters / Q000494:pharmacology; D011651:Pulmonary Artery / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012430:Ruthenium Red / Q000494:pharmacology; D050916:TRPV Cation Channels / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors
D010703:Phorbol Esters; D012333:RNA, Messenger; D050916:TRPV Cation Channels; C416986:TRPV4 protein, human; C486577:Trpv4 protein, rat; D012430:Ruthenium Red; C008876:phorbol-12,13-didecanoate; D002118:Calcium