Hormonal regulations of alkaline phosphatase, 5'-nucleotidase and gamma-glutamyltransferase activities in adult rat hepatocytes cultured in serum-free medium on collagen gel.

Primary hepatocytes were cultured on collagen gel in serum-free, alpha-modified Eagle's minimum essential medium containing 0.1 microM insulin, 0.1 microM dexamethasone, 10 mM pyruvate and supplements such as glucagon, epinephrine or growth hormone. The activities of alkaline phosphatase, 5'-nucleotidase and gamma-glutamyltransferase were assayed in cell extracts prepared from the cultures. All three enzyme activities were induced by glucagon, epinephrine or dibutyryl cAMP. The maximally effective concentration of glucagon was 5-10 nM for both alkaline phosphatase and 5'-nucleotidase and 100 nM for gamma-glutamyltransferase. Only alkaline phosphatase activity was suppressed by growth hormone, which caused marked suppression at about 1 microU (0.25 ng)/ml. Taurocholate also induced both alkaline phosphatase and gamma-glutamyltransferase activities at 1 mM.