ISSN:
1432-119X
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary The fine structural morphology and the ATP-ase activity of heart muscle at various sarcomere lengths was studied. ATP-ase activity was found on endothelial cells, cell membrane, intercalated disc, sarcoplasmic reticulum and in the Z-line region. It appeared that the activity of the ATP-splitting in the Z-line region was sensitive to PCMB and could be reactivated with cysteine. This points to an activity of “true” ATP-ase according to the terminology ofPadykula et al. (1955) andFreiman et al. (1960). In addition, this cross striational enzyme was strongly activated by Mg++. At intermediate sarcomere lengths and in hypercontraction no I-zones or H-zones were visible, while at intermediate sarcomere lengths and M-line was faintly indicated. In the stretched muscle, both I- and H-zones and N- and M-lines were present. In comparison with muscle tissue with intermediate sarcomere lengths, the Cz-bands of hypercontraction had markedly broadened, whereas in stretched muscle a relatively sharply defined electron-dispersing line indicated the presence of a Z-line. The localization and spread of the precipitate formed as a result of ATP-ase activity changes with alterations of the sarcomere lengths exclusively in the Z-line region. The probable identity of the Z-line region ATP-ase with Actomyosin is discussed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00736444
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