Phorbol esters do not influence the maturation and the beta-adrenergic responsiveness of differentiated adipose precursor cells, cultured in a charcoal-treated serum medium.

Phorbol esters are a well defined group of tumor-promoting substances, which influence the proliferation, the differentiation and the hormonal responsiveness of a wide variety of cell types through the activation of protein-kinase C. Opposite effects have been described on the beta-adrenoceptors and the adenylate cyclase activity, depending on the cell type. Since there is no information about the influence of these substances on lipolysis in adipose precursor cells, the aim of the present study was to examine the effect of 7 days exposure to phorbol esters on the differentiation and the lipolytic responsiveness of rat preadipocytes, cultured in 10% charcoal-treated fetal calf serum. Our results demonstrate that prolonged exposure to these tumor promoters does not influence the differentiation, the beta-adrenoceptors number and the lipolytic response to adenylate cyclase or beta-adrenergic agonists in differentiated cells.