Microsomal arachidonate bioconversion in rat small intestine during maturation

Abstract

This study was designed to compare prostaglandin (PG)-synthesizing activity in rat small intestinal microsomes in the lst, 3rd, and 6th weeks of life and at maturity (>100 days). When an incubation system was used containing 2 mg microsomal protein, 0.5 mM (−)-epinephrine and 1 mM reduced glutathione, the highest PG-synthesizing activity was achieved by incubating 0.157 mM 1-¹⁴C-arachidonate (specific activity 2.6 × 10⁶ dpm/μmol) at 37°C for 5 min. The labeled metabolites were extracted and then separated with high performance liquid chromatography. The four PGs analyzed were 6 keto-prostaglandin F₁α (6-keto-PGF_1α), thromboxane B₂, prostaglandin F_2α and prostaglandin E₂. Enzymatic activity for the synthesis of 6-keto-PGF_1α was much higher than that for the other PGs. A significant difference was observed for the bioconversion from arachidonate to 6-keto-PGF_1α and total PGs among the four age groups of rats. The postweanling groups (week 6 and adult) showed significantly higher enzymatic activities for the syntheses of 6-keto-PGF_1α and total PGs than did the preweanling groups (weeks 1 and 3).