Heart protein kinase C activity increases during progression of disease in the cardiomyopathic hamster.

Protein kinase C activity in the particulate fraction of the heart increases two-fold during mid-stage of disease in the cardiomyopathic hamster. No change in the corresponding enzyme activity occurs with aging in healthy control hamsters. In the solubilized particulate fraction of hearts from both myopathic and control animals, Ca++/phospholipid-dependent endogenous phosphorylation of proteins of Mr 26, 31, 45, 53, 69, 98, 105 and 126 kDa are observed. All of these proteins are more highly phosphorylated in the protein kinase C-enriched preparation from the myopathic heart compared to the control. No significant differences between myopathic and control hamsters are observed in the activities of protein kinase C or phosphoinositide-specific phospholipase C from heart cytosol.