Enzyme activities, isoenzyme pattern and alpha-1-adrenergic receptor number in primary cultured hepatocytes

Changes in the activities of pyruvate kinase, tyrosine aminotransferase and adenylate cyclase as well as in the number of alpha-1-adrenergic receptors of hepatocytes maintained in primary culture were investigated. During the culture in the presence of insulin and dexamethasone the activity of tyrosine aminotransferase (TAT) increased. The increase was suppressed by 12-O-tetradecanoylphorbol-13-acetate (TPA). The basic activity of adenylate cyclase increased; however, a weaker stimulation of the enzyme by glucagon was found. A loss of stimulation of pyruvate kinase by fructose-1,6-bisphosphate may result from phosphorylation of the enzyme. The number of alpha-1-adrenergic receptors decreased during culture, an event not influenced by TPA.