Myosin light chain kinase- and PKC-dependent contraction of LES and esophageal smooth muscle
- Authors
- Sohn, UD; Cao, WB; Tang, DC; Stull, JT; Haeberle, JR; Wang, CLA; Harnett, KM; Behar, J; Biancani, P
- Issue Date
- Aug-2001
- Publisher
- AMER PHYSIOLOGICAL SOC
- Keywords
- calcium stores; caldesmon; calmodulin; calponin; cat; second messenger system
- Citation
- AMERICAN JOURNAL OF PHYSIOLOGY-GASTROINTESTINAL AND LIVER PHYSIOLOGY, v.281, no.2, pp G467 - G478
- Journal Title
- AMERICAN JOURNAL OF PHYSIOLOGY-GASTROINTESTINAL AND LIVER PHYSIOLOGY
- Volume
- 281
- Number
- 2
- Start Page
- G467
- End Page
- G478
- URI
- https://scholarworks.bwise.kr/cau/handle/2019.sw.cau/25200
- DOI
- 10.1152/ajpgi.2001.281.2.G467
- ISSN
- 0193-1857
1522-1547
- Abstract
- In smooth muscle cells enzymatically isolated from circular muscle of the esophagus (ESO) and lower esophageal sphincter (LES), ACh-induced contraction and myosin light chain (MLC) phosphorylation were similar. Contraction and phosphorylation induced by purified MLC kinase (MLCK) were significantly greater in LES than ESO. ACh-induced contraction and MLC phosphorylation were inhibited by calmodulin and MLCK inhibitors in LES and by protein kinase C (PKC) inhibitors in ESO. Contraction of LES and ESO induced by the PKC agonist 1,2-dioctanoylglycerol (DG) was unaffected by MLCK inhibitors. Caldesmon and calponin concentration-dependently inhibited ACh-induced contraction of ESO and not LES. In ESO, caldesmon antagonist GS17C reversed caldesmon- but not calponin-induced ACh inhibition. GS17C caused contraction of permeabilized ESO but had much less effect on LES. GS17C-induced contraction was not affected by MLCK inhibitors, suggesting that MLCK may not regulate caldesmon- mediated contraction. DG-induced contraction of ESO and LES was inhibited by caldesmon and calponinin, suggesting that these proteins may regulate PKC-dependent contraction. We conclude that calmodulin and MLCK play a role in ACh-induced LES contraction, whereas the classical MLCK may not be the major kinase responsible for contraction and phosphorylation of MLC in ESO. ESO contraction is PKC dependent. Caldesmon and/or calponin may play a role in PKC-dependent contraction.
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