Functional differences in the acinar cells of the murine major salivary glands

In humans,approximately 90% of saliva is secreted by the 3 major salivary glands: the parotid (pg),the submandibular (smg),and the sublingual glands (slg). even though it is known that all 3 major salivary glands secrete saliva by a cl - dependent mechanism,salivary secretion rates differ greatly among these glands. the goal of this study was to gain insight into the properties of the ion-transporting pathways in acinar cells that might account for the differences among the major salivary glands. pilocarpine-induced saliva was simultaneously collected in vivo from the 3 major salivary glands of mice. when normalized by gland weight,the amount of saliva secreted by the pg was more than 2-fold larger than that obtained from the smg and slg. at the cellular level,carbachol induced an increase in the intracellular [ca2+] that was more than 2-fold larger in pg and smg than in slg acinar cells. carbachol-stimulated cl- efflux and the protein levels of the ca2+-activated cl- channel tmem16a,the major apical cl- efflux pathway in salivary acinar cells,were significantly greater in pg compared with smg and slg. in addition,we evaluated the transporter activity of the na+-k+-2cl- cotransporters (nkcc1) and anion exchangers (ae),the 2 primary basolateral cl- uptake mechanisms in acinar cells. the smg nkcc1 activity was about twice that of the pg and more than 12-fold greater than that of the slg. ae activity was similar in pg and slg,and both pg and slg ae activity was about 2-fold larger than that of smg. in summary,the salivation kinetics of the 3 major glands are distinct,and these differences can be explained by the unique functional properties of each gland related to cl- movement,including the transporter activities of the cl- uptake and efflux pathways,and intracellular ca2+ mobilization. © 2015 international & american associations for dental research.