Degradation of prostaglandin E2 in a primary culture of adult rat hepatocytes.

In a primary culture of rat hepatocytes, [5,6,8,11,12,14,15-3H]prostaglandin E2 showed maximal incorporation of radioactivity (5 to 8% of total added) into the whole cells at 15 to 30 min (37 degrees C) and the incorporation then decreased gradually. Treatment of the cells at acidic pH (at 2.5 for 10 min, 4 degrees C) followed by thin layer chromatographic analysis revealed that most of the radioactivity incorporated was associated with the cell surface and consisted of intact prostaglandin E2 and its metabolite(s). In the culture medium after 20 min incubation, the concentration of prostaglandin E2 had decreased by approximately 50% and its metabolite(s) appeared. However, incubation of [1-14C]prostaglandin E2 under the same culture conditions led to intracellular incorporation of radioactivity; more than 30% of radioactivity accumulated during a 2 to 3 h incubation period, but it was not in the form of either intact prostaglandin E2 or the metabolite corresponding to that of [5,6,8,11,12,14,15-3H]prostaglandin E2. These results indicate that prostaglandin E2 was associated with the surface of cultured hepatocytes and degraded into at least two metabolites. The fragment containing 14C-labeled terminal COOH was incorporated into the intracellular fraction and the residual fragment consisting mostly of the 3H-labeled portion was released from the cell surface into culture medium.