The role of gap junction membrane channels in secretion and hormonal action.

Connexins, gap junctions, and coupling are obligatory features of both endocrine and exocrine glandular epithelia. Evidence from these two types of tissues, and particularly from pancreatic islets and acini, indicates that cell-to-cell communication via gap junction channels is required for proper biosynthesis, storage, and release of specific secretory products. However, endocrine and exocrine glands express a different set of connexins and show opposite connexin and coupling changes in relation with the activation and inhibition of their secretory function. Also, several hormones modulate connexin and coupling expression, and junctional coupling affects hormonal stimulation. These observations indicate that gap junction channels play an important role in the control of secretion and hormonal action.