STUDIES ON PROSTAGLANDIN E IN GASTRIC JUICE

I. Its Evaluation of Quantitative Determination Methods and Significance in Normal Subjects

Abstract

The quantitative determination methods of Prostaglandin E (PGE) in gastric juice and the significance of its existence in normal subjects were studied. It was possible to determine the endogenous PGE by extracting with ethyl acetate, separating individual PG groups on silicic acid column chromatography, converting PGE to PGB by alkaline treatment and performing the radioimmunoassay using anti-PGB₁ serum. The final recovery of internal standard ³H-PGE₁ following all of these procedures ranged from 68.6% to 75.7%.
There was interconversion of PGE to PGA in an acidic solution of pH1.0 according to the frozen storage periods. Because, ³H-PGE₁ was characterized by gradual decrease of elution ratio appeared in the PGE fraction on silicic acid column chromatography to 97.5% after 3 days, 93.6% after 7 days and 82.9% after 14 days. Therefore, it was considered necessary to perform the determination within 1 week.
The concentration of PGE in the basal state of normal subjects was 262.7±25.7pg/ml(M±SE). After pentagastrin stimulation, the concentration of PGE showed a gradual decrease following an increase of secreted gastric juice volume. The total output of PGE in the basal state and after stimulation recorded 11.0±1.8 ng/h and 12.8±2.1 ng/h (M±SE), respectively. These values were neither statistically significant from basal levels (p>0.05), nor suggestive the possibility that the increased release of endogenous PG would be promoted by pentagastrin stimulation. Furthermore, no significant correlation was seen between the secretion of acid (BAO, MAO) or pepsin (BPO, SPO) and that of gastric PGE (acid and PGE secretion: r=0.21 in the basal state, r=0.37 after stimulation. Pepsin and PGE secretion: r=0.18 in the basal state, r=0.56 after stimulation).