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cGMP‐dependent protein kinase decreases calcium sensitivity of skinned cardiac fibers
Author(s) -
Pfitzer G.,
Rüegg J.C.,
Flockerzi V.,
Hofmann F.
Publication year - 1982
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(82)81095-8
Subject(s) - isometric exercise , protein kinase a , protein subunit , chemistry , biophysics , cardiac muscle , calcium , incubation , troponin , troponin i , enzyme , biochemistry , medicine , endocrinology , biology , organic chemistry , myocardial infarction , gene
Chemically skinned (Lubrol WX) cardiac muscle fibres produce half‐maximum isometric tension at pCa 6.18 (pH 6.7) in presence of MgATP (10 mM). After addition of cGMP (5 μM) and cGMP‐depenent protein kinase (0.1 μM), 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 fibres with cAMP of catalytic subunit of the cAMP‐dependent protein kinase. The shift in the Ca 2+ ‐sensitivity is associated with an increased incorporation of radioactivity into a M r 28 000 band (presumably troponin‐I) and a M r 145 000 band.