Effects of myosin light chain kinase inhibitors on carbachol-activated nonselective cationic current in guinea-pig gastric myocytes

1997 ◽  
Vol 434 (4) ◽  
pp. 346-353 ◽  
Author(s):  
Young Chul Kim ◽  
Sung Joon Kim ◽  
Tong Mook Kang ◽  
Suk Hyo Suh ◽  
Insuk So ◽  
...  
Keyword(s):  
Guinea Pig ◽  
Light Chain ◽  
Myosin Light Chain Kinase ◽  
Myosin Light Chain ◽  
Kinase Inhibitors ◽  
Cationic Current ◽  
Gastric Myocytes ◽  
Nonselective Cationic Current

Physiological regulation of epithelial tight junctions is associated with myosin light-chain phosphorylation

1997 ◽  
Vol 273 (4) ◽  
pp. C1378-C1385 ◽  
Author(s):  
Jerrold R. Turner ◽  
Brian K. Rill ◽  
Susan L. Carlson ◽  
Denise Carnes ◽  
Rachel Kerner ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Tight Junction ◽  
Tight Junctions ◽  
Light Chain ◽  
Myosin Light Chain Kinase ◽  
Myosin Light Chain ◽  
Kinase Inhibitors ◽  
Tight Junction Regulation ◽  
Tight Junction Permeability ◽  
Mlc Phosphorylation

Tight junctions serve as the rate-limiting barrier to passive movement of hydrophilic solutes across intestinal epithelia. After activation of Na+-glucose cotransport, the permeability of intestinal tight junctions is increased. Because previous analyses of this physiological tight junction regulation have been restricted to intact mucosae, dissection of the mechanisms underlying this process has been limited. To characterize this process, we have developed a reductionist model consisting of Caco-2 intestinal epithelial cells transfected with the intestinal Na+-glucose cotransporter, SGLT1. Monolayers of SGLT1 transfectants demonstrate physiological Na+-glucose cotransport. Activation of SGLT1 results in a 22 ± 5% fall in transepithelial resistance (TER) ( P< 0.001). Similarly, inactivation of SGLT1 by addition of phloridzin increases TER by 24 ± 2% ( P < 0.001). The increased tight junction permeability is size selective, with increased flux of small nutrient-sized molecules, e.g., mannitol, but not of larger molecules, e.g., inulin. SGLT1-dependent increases in tight junction permeability are inhibited by myosin light-chain kinase inhibitors (20 μM ML-7 or 40 μM ML-9), suggesting that myosin regulatory light-chain (MLC) phosphorylation is involved in tight junction regulation. Analysis of MLC phosphorylation showed a 2.08-fold increase after activation of SGLT1 ( P< 0.01), which was inhibited by ML-9 ( P < 0.01). Thus monolayers incubated with glucose and myosin light-chain kinase inhibitors are comparable to monolayers incubated with phloridzin. ML-9 also inhibits SGLT1-mediated tight junction regulation in small intestinal mucosa ( P < 0.01). These data demonstrate that epithelial cells are the mediators of physiological tight junction regulation subsequent to SGLT1 activation. The intimate relationship between tight junction regulation and MLC phosphorylation suggests that a critical step in regulation of epithelial tight junction permeability may be myosin ATPase-mediated contraction of the perijunctional actomyosin ring and subsequent physical tension on the tight junction.

ML-9, a myosin light chain kinase inhibitor, reduces intracellular Ca2+ concentration in guinea pig trachealis

2004 ◽  
Vol 486 (3) ◽  
pp. 325-333 ◽  
Author(s):  
Satoru Ito ◽  
Hiroaki Kume ◽  
Haruo Honjo ◽  
Itsuo Kodama ◽  
Hideki Katoh ◽  
...  
Keyword(s):  
Guinea Pig ◽  
Light Chain ◽  
Myosin Light Chain Kinase ◽  
Myosin Light Chain ◽  
Kinase Inhibitor
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