GASTRIC-SECRETION OF PLATELET-ACTIVATING-FACTOR AND PRECURSORS IN HEALTHY HUMANS - EFFECT OF PENTAGASTRIN

The release of platelet activating factor (PAF-ACETHER or PAF) and its precursors in the gastric lumen was assessed in 13 normal subjects in basal condition and after stimulation by gastrin. Acid, pepsin, and s ialic acid outputs were determined under the same conditions. Gastric juice was collected using a nasogastric tube after overnight fast in b asal condition for 60 minutes, then under pentagastrin infusion (6 mug /kg/hr for 60 minutes). Platelet activating factor was detected at low concentration in 4/13 subjects under basal condition (mean (SEM) 1.2 (0-6) pg/hr) while high concentrations of lyso platelet activating fac tor (6.1(1.8) mug/hr) and of alkyl-acyl-glycerophosphocholine (AAGPC) (11.5 (3) mug/hr) were found in 13 and 11 subjects, respectively. Plat elet activating factor was not detected during pentagastrin infusion, while lyso platelet activating factor and alkyl-acyl-glycerophosphocho line were detected in 13 and in 12 subjects, respectively. Compared wi th the basal condition these platelet activating factor precursors inc reased significantly (p<0.001) going up to fivefold baseline (31.8 (6. 8) mug/hr and 53 (9-3) mug/hr respectively) in response to pentagastri n. There was a positive correlation between platelet activating factor precursors and acid or pepsin output but not between platelet activat ing factor precursors and sialic acid. As sialic acid may be considere d an index of mucus glycoprotein degradation, it seems that gastrin st imulation of gastric epithelial cells results in a concomittant secret ion of platelet activating factor precursors, acid, and pepsin irrespe ctive of mucus glycoprotein degradation.