Control of ionic currents and fluid secretion by muscarinic agonists in exocrine glands

Abstract

Stimulation of muscarinic receptors in exocrine glands leads to a complex set of intracellular events involving activation of a GTP-binding protein, production of inositol trisphosphate, and release of Ca 2+ from the endoplasmic reticulum. One of the consequences of the ensuing rise in Ca 2+ is the activation of three classes of Ca 2+-dependent channels that are involved in the fluid secretion response of the glands. In addition, muscarinic stimulation closes the gap junction channels that link adjacent cells. Application of patch-clamp methods has helped to characterize the channels implicated in these processes. Whole-cell recordings using intracellular solutions containing GTP derivatives or inositol trisphosphate are currently used to study the chain of events that take place during muscarinic stimulation.