We develop a mathematical model of a salivary gland acinar cell with the objective of investigating the role of two
Cl
-
/
HCO
3
-
exchangers from the solute carrier family 4 (Slc4), Ae2 (Slc4a2) and Ae4 (Slc4a9), in fluid secretion. Water transport in this type of cell is predominantly driven by
Cl
-
movement. Here, a basolateral
Na
+
/
K
+
adenosine triphosphatase pump (NaK-ATPase) and a
Na
+
–
K
+
–
2
Cl
-
cotransporter (Nkcc1) are primarily responsible for concentrating the intracellular space with
Cl
-
well above its equilibrium potential. Gustatory and olfactory stimuli induce the release of
Ca
2
+
ions from the internal stores of acinar cells, which triggers saliva secretion.
Ca
2
+
-dependent
Cl
-
and
K
+
channels promote ion secretion into the luminal space, thus creating an osmotic gradient that promotes water movement in the secretory direction. The current model for saliva secretion proposes that
Cl
-
/
HCO
3
-
anion exchangers (Ae), coupled with a basolateral
Na
+
/
proton
(
H
+
) (Nhe1) antiporter, regulate intracellular pH and act as a secondary
Cl
-
uptake mechanism (Nauntofte in Am J Physiol Gastrointest Liver Physiol 263(6):G823–G837,
1992
; Melvin et al. in Annu Rev Physiol 67:445–469,
2005
.
https://doi.org/10.1146/annurev.physiol.67.041703.084745
). Recent studies demonstrated that Ae4 deficient mice exhibit an approximate
30
%
decrease in gland salivation (Peña-Münzenmayer et al. in J Biol Chem 290(17):10677–10688,
2015
). Surprisingly, the same study revealed that absence of Ae2 does not impair salivation, as previously suggested. These results seem to indicate that...

A Mathematical Model Supports a Key Role for Ae4 (Slc4a9) in Salivary Gland Secretion

10.1007/s11538-017-0370-6