Synthesis and release of glucagon by human salivary glands.

Pieces of human salivary glands were homogenised with acid-ethanol or acid-saline solutions immediately after surgical removal. With both extraction procedures the immunoreactive glucagon (IRG) content in the submaxillary glands was greater than in parotid glands as determined with a C-terminal reactive glucagon antiserum (30K). Higher amounts of IRG were determined in acid-saline extracts of submaxillary (18.5 +/- 2.5 VS 8.9 +/- 1.2 ng/g wet weight) and parotid (3.5 +/- 0.3 VS 2.9 +/- 0.3 ng/g wet weight) glands compared with concentrations obtained with acid-ethanol extracts. IRG material extracted with the latter procedure has similar immunological and biological characteristics as pancreatic glucagon. After fractionation of the acid-ethanol extracts on P-30 columns or gel electrophoresis, an immunoreactive peak of 3500 daltons was always obtained. Arginine, ephinephrine and low glucose concentrations stimulated glucagon release from both salivary glands. Active glucagon biosynthesis by these glands was established by the incorporation of 3H-L-tryptophan into a 3500 daltons polypeptide with specific immune reaction with 30K antiserum. These findings indicate that human salivary glands represent a source of extrapancreatic glucagon in man and may therefore contribute to the circulating levels of this hormone.