Differentiation of ob 17 preadipocytes to adipocytes. Triggering effects of clofenapate and indomethacin.

Conversion of ob 17 preadipocytes to mature adipose cells is accelerated by addition of clofenapate or of indomethacin, in either the absence or presence of insulin. General stimulation of triacylglycerol-pathway enzymes is observed, as well as dramatic increase in endogenous fatty-acid synthesis. This increase is a function of drug concentration and exposure time. In contrast to indomethacin, the continuous presence of clofenapate after the cells reached confluence was required to observe the effects on adipose conversion. Growth of ob 17 fibroblasts in the presence of 5-bromo-2'-deoxyuridine normally prevents their differentiation to adipose cells. Addition of either clofenapate or indomethacin to these cells at confluence overrides this block. The effects of hypolipidemic drugs such as clofenapate observed on a long-term basis in vitro are consistent with the results of studies on adipose tissue in vivo.