The possibility of a short-term cAMP-dependent regulation of mixed-function oxidation and of glucuronide formation was investigated in isolated mouse hepatocytes and in mouse liver microsomal membranes. N6, O2-dibutyryl cAMP (in accordance with its increasing effect on gluconeogenesis) decreased aminopyrine oxidation and p-nitrophenol conjugation in isolated hepatocytes, while the phenolphthalein conjugation remained unaltered. Similar to dibutyryl cAMP the Ca2+ ionophore A 23187 also decreased aminopyrine oxidation. In cell-free systems the phosphorylation of isolated microsomal membranes by the exogenous cAMP-dependent protein kinase was inhibitory on amino-pyrine oxidation and p-nitrophenol glucuronide formation but aniline oxidation and phenolphthalein glucuronidation were not affected. The correlation between the negative cAMP-dependent control of certain processes of biotransformation and the positive cAMP-dependent regulation of gluconeogenesis is discussed.
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