Enhanced Ca2++-dependent activation of phosphoinositide 3-kinase class IIα isoform-Rho axis in blood vessels of spontaneously hypertensive rats
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Rho-mediated inhibition of myosin light chain (MLC) phosphatase (MLCP), together with Ca-dependent MLC kinase activation, constitutes the major signaling mechanisms for vascular smooth muscle contraction. We recently unveiled the involvement of Ca-induced, phosphoinositide 3-kinase (PI3K) class IIα isoform (PI3K-C2α)-dependent Rho activation and resultant Rho kinase-dependent MLCP suppression in membrane depolarization- and receptor agonist-induced contraction. It is unknown whether Ca- and PI3K-C2α- dependent regulation of MLCP is altered in vascular smooth muscle of hypertensive animals and is involved in hypertension. Therefore, we studied the role of the Ca-PI3K-C2α-Rho-MLCP pathway in spontaneously hypertensive rats (SHRs). PI3K-C2α was readily detected in various vascular beds of Wistar-Kyoto rats and activated by high KCl. High KCl also stimulated vascular Rho activity and phosphorylation of the MLCP regulatory subunit MYPT1 at Thr in a PI3K inhibitor wortmannin-sensitive manner. In mesenteric and other vessels of SHRs at the hypertensive but not the prehypertensive stage, the activity of PI3K-C2α but not class I PI3K p110α was elevated with concomitant rises of Rho activity and Thr-phosphorylation of MYPT1, as compared with normotensive controls. Infusion of the Ca channel antagonist nicardipine reduced blood pressure with suppression of vascular activity of PI3K-C2α-Rho and phosphorylation of MYPT1 in hypertensive SHRs. Infusion of wortmannin lowered blood pressure with inhibition of PI3K-C2α-Rho activities and MYPT1 phosphorylation in hypertensive SHRs. These observations suggest that an increased activity of the Ca-PI3K-C2α-Rho signaling pathway with resultant augmented MLCP suppression contributes to hypertension in SHRs. The Ca- and PI3K-C2α-dependent Rho stimulation in vascular smooth muscle may be a novel, promising target for treating hypertension. © 2010 American Heart Association, Inc.
金沢大学医薬保健研究域医学系
収録刊行物
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- Hypertension
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Hypertension 56 (5), 934-941, 2010-11-01
American Heart Association
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詳細情報 詳細情報について
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- CRID
- 1050001335948220544
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- NII論文ID
- 120002661948
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- NII書誌ID
- AA00214236
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- ISSN
- 0194911X
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- HANDLE
- 2297/25788
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- 本文言語コード
- en
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- 資料種別
- journal article
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- データソース種別
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- IRDB
- CiNii Articles