The A-, D-, and B-cells - the islet cells that contain, respectively, immunoreactive glucagon, somatostatin, and insulin - are distributed within a specialized heterocellular region of the islets of Langerhans as if to permit heterologous contacts between all 3 cell types. Inasmuch as each one of the 3 secretory products of these 3 cell types influences the secretion of at least one of its neighboring cells, 'paracrine' influence on islet hormone secretion becomes a reasonable hypothesis. Glucagon stimulates both insulin and somatostatin release, while insulin and somatostatin both inhibit glucagon release, providing the basis for a feedback relation through which A-cell secretion may be restrained. In addition, glucagon-mediated insulin secretion may be restrained by glucagon-stimulated somatostatin release. Such intercellular relation could help determine the composition of the insulin and glucagon mixtures released within a given metabolic setting.
ASJC Scopus subject areas
- Internal Medicine
- Endocrinology, Diabetes and Metabolism