ISSN:
1435-1803
Keywords:
myosin light chain kinase
;
myosin P-light chain phosphorylation
;
Ca2+-sensitivity
;
skinned cardiac fibres
;
unloaded shortening velocity
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary We investigated the influence of myosin P-light chain phosphorylation by Ca2+-calmodulin dependent myosin light chain kinase (MLCK) on the sensitivity of the tension-pCa relation and maximum unloaded shortening velocity (v max) of chemically skinned heart fibres of the pig. Submaximum Ca2+ stimulation (pCa 5.5) induced 20±5% of the isometric tension achieved at maximum Ca2+ activation (pCa 4.3). MLCK-induced myosin P-light chain phosphorylation increased the isometric force development at pCa 5.5 by 40% whereas maximum tension at pCa 4.3 was not affected. Unloaded shortening velocity (v max) was not altered by myosin P-light chain phosphorylation either at maximum or at submaximum Ca2+ concentration, being c. 1.2 muscle length/s at pCa 5.5 and 2.2 muscle length/s at pCa 4.3. The MLCK-induced increase of the myosin P-light chain phosphorylation level was evaluated by determination of32P-incorporation. Two phosphorylatable myosin P-light chains could be demonstrated.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02005185
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