Abstract
A scheme is described for comprehensive quantitation of mucosubstances in gastric juice and mucus and its application to the study of the mucous secretions under a variety of conditions. Chondroitin sulfate A and sulfated glycoproteins are measured by a modification of the turbidimetric method of De Graef and Glass, using chondroitin sulfate A and gastric sulfated glycoprotein standards. The non-sulfated glycoproteins (including the sialomucins and blood group substances types) are measured either by the fucose assay of the papain digested gastric juice or mucus, with a correction for fucose content of sulfated glycoproteins, or by the recently developed turbidimetric method. The latter compares turbidity of the cetylpyridinium supernatant of the papain digested gastric juice or mucus after addition of buffered ethanol with the turbidity of the gastric non-sulfated glycoprotein standard under similar conditions. The measurements were performed in fasting gastric content and after histamine, pentagastrin and insulin stimulation in 45 individuals with and without gastric disease. Chondroitin sulfate A and C are absent or present only in traces in gastric secretion of man. Sulfated glycoproteins are present at a relatively high concentration in gastric mucus and fasting gastric residual content, but at a low concentration in the basal secretion, and after histamine, pentagastrin and insulin stimulation. Non-sulfated glycoproteins form the bulk of gastric glycoproteins in man, both in mucus and gastric juice.