December 6, 2006
First described in red blood cells in the late 1950s, calcium-activated potassium channels today are known to play myriad physiological roles throughout the human body. Included prominently among these tasks is maintaining vascular tone to red blood cells, regulating the firing rate of neurons, and controlling the secretion of the salivary gland. For several years, a team of NIDCR grantees has attempted to define the interplay between the two distinct types of calcium-activated potassium channels in the clustered, grape-like acinar cells of the parotid salivary gland. The parotid gland, located just below the ear, produces about 25 percent of human saliva. The group previously cloned, characterized, and created a mouse that lacked the gene that regulated one of these channels, called the IK1 channel. In the September 22 issue of the Journal of Biological Chemistry, the scientists characterize the other channel called the Maxi-K channel. They found not only do the two channels regulate the rate of fluid secretion, they control the ionic composition and volume of the salivary acinar cells. As researchers move forward in helping the millions of Americans battling the chronic irritation of dry mouth, understanding of the more subtle features of this interplay will be critical in designing winning strategies to restore lost salivary flow.