Chemical characterization of persistent immunoreactive glucagon in eviscerated rats

Extraction of rat submaxillary salivary glands and ileal mucosa yielded a single immunoreactive glucagon component of 25,000 daltons and a major peak of approximately 9,000 daltons respectively. Eviscerated rats with and without functional livers were found to have decreased, but persistent levels of immunoreactive glucagon and total immunoreactive glucagon, as measured with a pancreatic specific and cross reacting antiserum respectively. Gel filtration of serum samples on Sephadex G-50 fine and G-200 superfine demonstrated that there was no measurable 3485, 9000 or 25,000 dalton glucagon immunoreactivity. The persistent immunoreactive glucagon in the serum of eviscerated rats is a heterogeneous mixture of nonspecific materials and does not contain submaxillary or intestinal glucagon-related materials. These findings suggest caution in the interpretation of glucagon immunoreactivity in serum and demonstrate the necessity for chromatographic analysis of circulating IRG.