Essential role of rho kinase in the Ca2+ sensitization of prostaglandin F2α-induced contraction of rabbit aortae

被引:70
作者
Ito, K [1 ]
Shimomura, E
Iwanaga, T
Shiraishi, M
Shindo, K
Nakamura, J
Nagumo, H
Seto, M
Sasaki, Y
Takuwa, Y
机构
[1] Miyazaki Univ, Fac Agr, Dept Vet Pharmacol, Miyazaki 8892192, Japan
[2] Asahi Kasei Corp, Frontier Project 21, Inst Life Sci Res, Fuji, Shizuoka 4168501, Japan
[3] Kitasato Inst, Dept Pharmacol, Fac Pharm, Tokyo 1088641, Japan
[4] Kanazawa Univ, Sch Med, Dept Physiol, Kanazawa, Ishikawa 9208640, Japan
来源
JOURNAL OF PHYSIOLOGY-LONDON | 2003年 / 546卷 / 03期
关键词
D O I
10.1113/jphysiol.2002.030775
中图分类号
Q189 [神经科学];
学科分类号
071006 ;
摘要
Inhibition of dephosphorylation of the 20 kDa myosin light chain (MLC20) is an important mechanism for the Ca2+-induced sensitization of vascular smooth muscle contraction. We investigated whether this mechanism operates in prostaglandin F-2alpha (PGF(2alpha))-induced contraction of rabbit aortic smooth muscle and, if so, whether protein kinase C (PKC) or rho-associated kinase (rho kinase) contribute to the inhibition of dephosphorylation. In normal medium, PGF(2alpha) (10 muM) increased the phosphorylation of MLC20 and developed tension. The rho-kinase inhibitors fasudil and hydroxyfasudil inhibited these changes, despite having no effect on a phorbol-ester-induced MLC20 phosphorylation. After treatment with verapamil or chelation of external Ca2+ with EGTA, PGF(2alpha) increased the MLC20 phosphorylation and tension without an increase in [Ca2+](i), all of which were sensitive to fasudil and hydroxyfasudil. ML-9, a MLC kinase inhibitor, quickly reversed the KCl-induced MLC20 phosphorylation and contraction to the resting level. However, fractions of PGF(2alpha)-induced contraction and MLC20 phosphorylation were resistant to ML-9 but were sensitive to fasudil. Ro31-8220 (10 muM), a PKC inhibitor, did not affect the phosphorylation of MLC20 and the tension caused by PGF(2alpha), thus excluding the possibility of the involvement of PKC in the PGF(2alpha)-induced MLC20 phosphorylation. PGF(2alpha) increased phosphorylation at Thr654 of the myosin binding subunit (MBS) of myosin phosphatase, which is a target of rho kinase, and fasudil decreased the phosphorylation. These data suggest that the PGF(2alpha)-induced contraction is accompanied by the inhibition of MLC20 dephosphorylation through rho kinase-induced MBS phosphorylation, leading to Ca2+ sensitization of contraction. An actin-associated mechanism may also be involved in the PGF(2alpha)-induced sensitization.
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收藏
页码:823 / 836
页数:14
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