cGMP-dependent protein kinase decreases calcium sensitivity of skinned cardiac fibers.
Chemically skinned (Lubrol WX) cardiac muscle fibers produce half-maximum isometric tension at pCa 6.18 (pH 6.7) in presence of MgATP (10 mM). After addition of cGMP (5 microM) and cGMP-dependent protein kinase (0.1 microM), the pCa required for half-maximum activation is 5.96, while maximum tension is not affected. Similar shifts in the tension/pCa-relationship have been observed after incubation of skinned cardiac muscle fibers with cAMP of catalytic subunit of the cAMP-dependent protein kinase. The shift in the Ca2+-sensitivity is associated with an increased incorporation of radioactivity into a Mr 28000 band (presumably troponin-I) and a Mr 145000 band.
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002147:Calmodulin / Q000494:pharmacology; D006152:Cyclic GMP / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D008970:Molecular Weight; D009200:Myocardial Contraction / Q000187:drug effects*; D011494:Protein Kinases / Q000378:metabolism*; D013268:Stimulation, Chemical; D013552:Swine
D002147:Calmodulin; D011494:Protein Kinases; D006152:Cyclic GMP; D002118:Calcium; D015056:1-Methyl-3-isobutylxanthine