“…With Lnc r-ea s i n.; concentrations of glucose placed on the mucosal -ridc ,'il i l l is generated implying increasing Na+ absorption. to be due to two components, an endogenous [']',}, pn 13 , both of which increase with Lnc r'oa s i 11,:0', increasing capacity to absorb Na.+ and hence water. Studies of the Nt dependence of the endogenous PD 12 by lowering the NaCl concentration of the mucosal solution show that there is a reversal of polarity of the PD, the mucosa becoming positive compared to the serosa, implying that the diffusional pathway is allowing Na+ ions through but not ci ' ions, i.e.…”