Influence of the nature of the secretory stimulus on the composition of the carbohydrate moiety of glycoproteins of the submaxillary saliva

Abstract The submaxillary saliva of the dog produced after electric stimulation of the parasympathetic nerve chorda tympani or after administration of pilocarpine or acetylcholine contains a nondialyzable carbohydrate combined with protein in a ratio of about 1:1. This carbohydrate contains galactose, small amounts of mannose, glucosamine, and galactosamine in a ratio of 3:2, fucose, and neuraminic acid. The molar ratio of the sum of fucose and neuraminic acid (calculated under the assumption that it is present as sialic acid) to total hexosamine is very nearly 1, shows only small variations in salivas from individual animals, and appears very little dependent on the nature or the intensity of the stimulus. The molar ratio of neuraminic acid to fucose on the other hand varies in a wide range (0.16–2.6) with the dose of pilocarpine and shows also greater variations in salivas from individual animals. In salivas after electrical stimulation of the nerve, the ratio of neuraminic acid to fucose proved to be independent of the intensity of the stimulus and to vary to a much lesser degree from one animal to another. Superimposition of intra-arterial injections of acetylcholine on electrical nerve stimulation produces in the salivary carbohydrate a higher ratio of neuraminic acid to fucose than is obtained with nerve stimulation alone. The centrifugal patterns of salivary glycoproteins obtained with maximal doses of pilocarpine with an intermediate ratio of sialic acid to fucose of 0.75 consist of only one sharp peak.