July 9, 2007
Dr. Irwin Mandel, the now retired pioneer of salivary research, once referred to the salivary gland as “the original slow-release device,” humorously comparing it to the glut of time release capsules, insulin pumps, and other manner of long-lasting therapeutic devices on the market. Yet, much remains to be learned regarding the spatial, temporal, and biochemical dynamics of fluid secretion in the slow-release salivary gland. Published online on May 3 in the Journal of Theoretical Biology, NIDCR grantees provide an interesting mathematical model of the water flow in an isolated acinar cell from the parotid salivary gland. Acinar cells secrete the primary salivary fluid and most of the salivary proteins. As the authors noted, the model takes into account the rate of change of intracellular ion concentrations, cell volume, membrane potential, and water flow rate. Based on this model, calcium oscillations lead to oscillations in fluid flow. The authors conclude that the average calcium concentrations, not the frequency of the oscillations, regulate the rate of fluid flow.