title: A dynamic model of saliva secretion.
abstract: We construct a mathematical model of the parotid acinar cell with the aim of investigating how the distribution of K(+) and Cl(-) channels affects saliva production. Secretion of fluid is initiated by Ca(2+) signals acting on Ca(2+) dependent K(+) and Cl(-) channels. The opening of these channels facilitates the movement of Cl(-) ions into the lumen which water follows by osmosis. We use recent results into both the release of Ca(2+) from internal stores via the inositol (1,4,5)-trisphosphate receptor (IP(3)R) and IP(3) dynamics to create a physiologically realistic Ca(2+) model which is able to recreate important experimentally observed behaviours seen in parotid acinar cells. We formulate an equivalent electrical circuit diagram for the movement of ions responsible for water flow which enables us to calculate and include distinct apical and basal membrane potentials to the model. We show that maximum saliva production occurs when a small amount of K(+) conductance is located at the apical membrane, with the majority in the basal membrane. The maximum fluid output is found to coincide with a minimum in the apical membrane potential. The traditional model whereby all Cl(-) channels are located in the apical membrane is shown to be the most efficient Cl(-) channel distribution.
authors.affiliation: Department of Mathematics, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand. l.palk@math.auckland.ac.nz
authors.forename: Laurence
authors.initials: L
authors.lastname: Palk
authors.forename: James
authors.initials: J
authors.lastname: Sneyd
authors.forename: Trevor J
authors.initials: TJ
authors.lastname: Shuttleworth
authors.forename: David I
authors.initials: DI
authors.lastname: Yule
authors.forename: Edmund J
authors.initials: EJ
authors.lastname: Crampin
mesh_terms: D001692:Biological Transport; D002118:Calcium / Q000378:metabolism; D018118:Chloride Channels / Q000378:metabolism; D025461:Feedback, Physiological; D006801:Humans; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000378:metabolism; D007700:Kinetics; D008564:Membrane Potentials; D008954:Models, Biological; D010539:Permeability; D015221:Potassium Channels / Q000378:metabolism; D012212:Rheology; D019837:Ryanodine Receptor Calcium Release Channel / Q000378:metabolism; D012463:Saliva / Q000378:metabolism*; D012472:Salivation / Q000502:physiology*; D019108:Tight Junctions / Q000378:metabolism; D014867:Water / Q000378:metabolism
chemical_list: D018118:Chloride Channels; D053496:Inositol 1,4,5-Trisphosphate Receptors; D015221:Potassium Channels; D019837:Ryanodine Receptor Calcium Release Channel; D014867:Water; D002118:Calcium