Increased calcium sensitivity of chemically skinned human atria by myosin light chain kinase.
We investigated the influence of myosin P-LC phosphorylation catalysed by calcium/calmodulin-dependent myosin light chain kinase ( MLCK) on the tension-pCa relation of chemically skinned human atrial fibres. MLCK- induced increased myosin P-LC phosphorylation sensitized human atrial skinned fibres for calcium by 0.11 pCa-units in patients with valvular heart disease, and by 0.05 to 0.07 pCa-units in patients with coronary heart disease. The MLCK effect could be antagonized by a light chain phosphatase. The protein phosphatase ocadaic acid (OA) had no influence on the tension-pCa relation of skinned human atrial fibres and had no potentiating effect together with MLCK. The MLCK preparation used in this study was from bovine ventricle and revealed a KM of 1.8 x 10(-5) M and a Vmax of 822 nmol Pi/min/mg using purified bovine ventricular myosin-LCs as substrate.[1]References
- Increased calcium sensitivity of chemically skinned human atria by myosin light chain kinase. Morano, I., Bächle-Stolz, C., Katus, A., Rüegg, J.C. Basic Res. Cardiol. (1988) [Pubmed]
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