Degradation of Prostaglandin E2 in a Primary Culture of Adult Rat Hepatocytes1

Abstract

In a primary culture of rat hepatocytes, [5,6,8,11,12,l4,15- ³ H]prostaglandin E ₂ showed maximal incorporation of radioactivity (5 to 8% of total added) into the whole cells at 15 to 30 mm (37°C) and the incorporation then decreased gradually. Treatment of the cells at acidic pH (at 2.5 for 10 min, 4°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 E ₂ and its metabolite(s). In the culture medium after 20 min incubation, the concentration of prostaglandin E ₂ had decreased by approximately 50% and its metabolite(s) appeared. However, incubation of [1- ¹⁴ C]prostaglandin E ₂ 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 E ₂ or the metabolite corresponding to that of [5,6,8,11,12,1 4,15- ³ H]prostaglandin E ₂ . These results indicate that prostaglandin E ₂ was associated with the surface of cultured hepatocytes and degraded into at least two metabolites. The fragment containing ¹⁴ C-labeled terminal COOH was incorporated into the intracellular fraction and the residual fragment consisting mostly of the ³ H-labeled portion was released from the cell surface into culture medium.