Fig. 8. Schematic representation of fluid secretion by the conjunctiva. Cellular mechanism of conjunctival Clsecretion and Na+ absorption identified in the conjunctival epithelium. Isc, short circuit current; Rt, tissue resistance. Na+-coupled glucose and Na+-coupled amino acid (AA) transporters are responsible for apical Na+ absorption. Cltransport is dependent on basolaterally located NKCC. (Reprinted from Dartt DA: Regulation of mucin and fluid secretion by conjunctival epithelial cells. Prog Retin Eye Res 21:555–576, 2002.)