title: Biochemical and morphological correlates of cardiac ischaemia: Contractile proteins.
abstract: Experimentally-induced ischaemia in the dog heart was produced by ligating the left circumflex artery. Myosin B isolated from the ischaemic portion of the myocardium differed from myosin B isolated from control tissue in its diminished response to the calcium chelator ethyleneglycol bis (beta-amino-ethylether)-N, N'-tetraacetic acid (EGTA). In the presence of EGTA, ischaemic myosin B required 2.5 +/- 0.5 min for completion of superprecipitation, whereas control myosin B required 6.6 +/- 2.5 min. Likewise, the Mg++ -activated ATPase activity of ischaemic myosin B was inhibited by EGTA to a lesser degree than control myosin B. Experiments with reconstituted myosin B using desensitized control myosin B and regulatory proteins suggest that ischaemia induces changes in the regulatory proteins (troponin and tropomyosin).
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D011232:Chemical Precipitation; D003327:Coronary Disease / Q000378:metabolism* / Q000473:pathology; D004285:Dogs; D009206:Myocardium / Q000032:analysis / Q000473:pathology; D009218:Myosins / Q000032:analysis / Q000378:metabolism*; D014335:Tropomyosin / Q000378:metabolism; D014336:Troponin / Q000378:metabolism
chemical_list: D014335:Tropomyosin; D014336:Troponin; D000251:Adenosine Triphosphatases; D009218:Myosins