Okano M, Uchikawa Y, Tanaka N, Mutoh J, Ohkura M, Hisa H, Yamamoto R. Rho-kinase, but not protein kinase C, is involved in generation of the spontaneous tone in the resting phase of the isolated pig iris sphincter muscle.
Curr Eye Res 2009;
34:177-83. [PMID:
19274524 DOI:
10.1080/02713680802652175]
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Abstract
PURPOSE
The purpose of the present study was to clarify the role of Rho-kinase and/or protein kinase C in the resting tension of the isolated pig iris sphincter muscle.
MATERIALS AND METHODS
The motor activity of the isolated pig iris sphincter muscle was measured isometrically.
RESULTS
EGTA, a chelator of extracellular Ca(2+), significantly reduced the resting tension. Y27632, a Rho-kinase inhibitor, significantly reduced the resting tension in a concentration-dependent manner. The resting tension diminished by Y27632 was significantly recovered by the addition of calyculin A, a myosin light chain phosphatase (MLCP) inhibitor, in a concentration-dependent manner. GF109203X, a protein kinase C inhibitor, had no effect on the resting tension.
CONCLUSION
These results suggest that, in the isolated pig iris sphincter muscle, Rho-kinase plays an important role in the generation of spontaneous tone in the resting phase via the inhibition of MLCP activity.
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