Effects of Beverage Ingredients on Salivary Fluid Secretion with an ex Vivo Submandibular Gland Perfusion System: Tannic Acid as a Key Component for the Inhibition of Saliva Secretion

Tannic acid (TA) and TA containing beverage have been proved to inhibit Ca2+-activated Cl− channel located apical membrane of the secretory cells. However, their effect on salivary fluid secretion is not well investigated. We used mouse ex vivo submandibular gland perfusion technique to identify the general effect of TA and related beverage samples on muscarinic agonist carbachol induced fluid secretion. Green tea inhibited fluid secretion by 64% from the control, where oolong tea was by 53%, and red wine by 43% which was linked with their TA concentration. On the other hand, though TA was contained at 4.7 μM in white wine sample and 33 μM in coffee extract, no adverse effect was observed. In addition, coffee induced salivation in the absence of carbachol. TA had a negative effect on fluid secretion with a concentration dependent manner. The effects of TA on carbachol induced calcium increase showed identical as fluid secretion, which was initially no effect, and then gradually decreased over the time. These results demonstrate that TA directly inhibits the salivary fluid secretion and it affects not only Ca2+-activated Cl− channel but also intracellular Ca2+ increasing mechanisms.