Discrepancies between gastric mucosal and urinary pepsinogen A patterns and in vitro synthesis and secretion of human pepsinogen.

ABSTRACT

The relationship between electrophoretic pepsinogen A (PGA) patterns from urine and gastric mucosa was studied in healthy volunteers and in patients with various gastric disorders. Discrepancies between urinary and gastric PGA patterns were found in 63.3% of the individuals. In 9% of the subjects with these discrepancies, the phenotype class in urine was different from that in gastric mucosa. The differences were found in all diagnostic groups. The highest frequency of differences was found in patients with gastric ulcer. The differences were not related to the serum PGA level. More than 80% of the differences were caused by a lower relative intensity of pepsinogen A fraction 5 (Pg5) in urine than in gastric mucosa. The possible origin of differences in PGA isozymogen patterns was studied by organ culture of gastric biopsies. In vitro synthesis and secretion of pepsinogens were studied by electrophoresis and autoradiography. The synthesis rate of PGA in biopsies of 1-2 mm diameter was 40-100 ng/hr. Posttranslational modification of PGA isozymogens was demonstrated. Pg2 and part of Pg4 probably are secondary products of Pg3 and Pg5, respectively. In some individuals the secretion rate of Pg3 was low compared to the other isozymogens. The conversion of Pg3 into Pg2 and the differential secretion of the isozymogens may explain some of the discrepancies between gastric and urinary PGA patterns.