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Enhanced contractility and myosin phosphorylation induced by Ca(2+)-independent MLCK activity in hypertensive rats.

Authors
 Young-Eun Cho ; Duck-Sun Ahn ; Young-Ho Lee ; Kathleen G. Morgan 
Citation
 Cardiovascular Research, Vol.91(1) : 162~170, 2011 
Journal Title
 Cardiovascular Research 
ISSN
 0008-6363 
Issue Date
2011
Abstract
AIMS: The role of Ca(2+) sensitization induced by a Ca(2+)-independent myosin light chain kinase (MLCK) in hypertension has not been determined. The aim of this study was to clarify the role of possible Ca(2+)-independent MLCK activity in hypertension. METHODS AND RESULTS: We compared increases in contractile force and phosphorylation of myosin light chain (MLC) evoked by calyculin A, a phosphatase inhibitor, in β-escin-permeabilized mesenteric arteries at pCa 9.0 between spontaneously hypertensive rat (SHR) and Wistar Kyoto rat (WKY). We found that there was no detectable phosphorylation of MLC at pCa 9.0, but that the administration of 1 μM calyculin A gradually increased force and mono- and di-phosphorylation of MLC. This contraction was inhibited by staurosporine but not by wortmannin, Y-27632, or calphostin-C. The calyculin A-induced contraction was significantly greater in the SHR than in the WKY and was associated with an increase in mono- and di-phosphorylation of MLC. SM-1, a zipper-interacting protein kinase (ZIPK)-inhibiting peptide, significantly inhibited the amplitude of the calyculin A-induced contraction and di-phosphorylation. Total ZIPK expression (54 + 32 kDa) was greater in the SHR than in the WKY. Phosphorylation of myosin phosphatase target subunit at Thr(697), but not at Thr(855), was consistently stronger in the SHR than in the WKY in calyculin A-treated tissues at pCa 9.0. CONCLUSIONS: Our results suggest that Ca(2+)-independent MLCK activity is enhanced in the SHR, and that ZIPK plays, at least in part, an important role as a candidate for this kinase in rat mesenteric arteries.
URI
http://ir.ymlib.yonsei.ac.kr/handle/22282913/93399
DOI
10.1093/cvr/cvr043
Appears in Collections:
1. 연구논문 > 1. College of Medicine > Dept. of Physiology
Yonsei Authors
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