Compartmentation of Hormone Action in Adult Mammalian Cardiomyocytes
Our interests in hormone action on mammalian heart have led us to explore the hormonal responsiveness of purified adult ventricular cardiomyocytes. In this report, we shall describe cardiomyocytes from both rat and rabbit that retain excellent biochemical homology with the intact heart and possess an abundance of receptors for adrenergic and cholinergic hormones that regulate the metabolism and contraction of cardiac muscle. Our data demonstrate the utility of the purified cardiomyocyte preparation in questions about the distribution of hormonal responsiveness between myocyte and non-myocyte elements of cardiac tissue. In addition, our data demonstrate the subcellular basis of hormone-specific compartmentation of cyclic AMP (cAMP) and cAMP-protein kinase (cAMP-PK) in cardiomyocytes, implying that the expression of cAMP-PK activity is regulated intracellularly by factors in addition to cAMP.
KeywordsGlycogen Phosphorylase Hormonal Responsiveness Particulate Frac Prazosin Binding Total Protein Kinase
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