Open AccessRestoration of uridine 5′‐triphosphate‐suppressed delayed rectifying K + currents by an NO activator KMUP‐1 involves RhoA/Rho kinase signaling in pulmonary artery smooth muscle cells
Author(s) -
Dai ZenKong,
Kao ChangLing,
Hsieh SuLing,
Chen IngJun,
Wu BinNan
Publication year - 2016
Publication title -
the kaohsiung journal of medical sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.439
H-Index - 36
eISSN - 2410-8650
pISSN - 1607-551X
DOI - 10.1016/j.kjms.2016.09.008
Subject(s) - rhoa , rho associated protein kinase , uridine triphosphate , depolarization , protein kinase c , kinase , signal transduction , microbiology and biotechnology , pharmacology , medicine , biology , chemistry , biochemistry , nucleotide , gene
We have demonstrated that KMUP‐1 (7‐[2‐[4‐(2‐chlorobenzene)piperazinyl]ethyl]‐1,3‐dimethylxanthine) blunts monocrotaline‐induced pulmonary arterial hypertension by altering Ca 2+ sensitivity, K + ‐channel function, endothelial nitric oxide synthase activity, and RhoA/Rho kinase (ROCK) expression. This study further investigated whether KMUP‐1 impedes uridine 5′‐triphosphate (UTP)‐inhibited delayed rectifying K + (K DR ) current in rat pulmonary arteries involved the RhoA/ROCK signaling. Pulmonary artery smooth muscle cells (PASMCs) were enzymatically dissociated from rat pulmonary arteries. KMUP‐1 (30μM) attenuated UTP (30μM)‐mediated membrane depolarization and abolished UTP‐enhanced cytosolic Ca 2+ concentration. Whole‐cell patch‐clamp electrophysiology was used to monitor K DR currents. A voltage‐dependent K DR current was isolated and shown to consist of a 4‐aminopyridine (5mM)‐sensitive component and an insensitive component. The 4‐aminopyridine sensitive K DR current was suppressed by UTP (30μM). The ROCK inhibitor Y27632 (30μM) abolished the ability of UTP to inhibit the K DR current. Like Y27632, KMUP‐1 (30μM) similarly abolished UTP‐inhibited K DR currents. Superfused protein kinase A and protein kinase G inhibitors (KT5720, 300nM and KT5823, 300nM) did not affect UTP‐inhibited K DR currents, but the currents were restored by adding KMUP‐1 (30μM) to the superfusate. KMUP‐1 reversal of K DR current inhibition by UTP predominantly involves the ROCK inhibition. The results indicate that the RhoA/ROCK signaling pathway plays a key role in eliciting PASMCs depolarization caused by UTP, which would result in pulmonary artery constriction. KMUP‐1 blocks UTP‐mediated PASMCs depolarization, suggesting that it would prevent abnormal pulmonary vasoconstriction.