A QUANTITATIVE DESCRIPTION OF THE NA-K-2CL COTRANSPORTER AND ITS CONFORMITY TO EXPERIMENTAL-DATA

In epithelia, the Na-K-2Cl cotransporter cooperates with other transpo rt mechanisms to produce transepithelial NaCl transport. The reaction cycle for the Na-K-2Cl cotransporter has been established experimental ly, but whether it accounts, quantitatively, for experimental findings has yet to be established. The differential equations that describe t he reaction cycle were formulated, and the steady-state solutions were obtained by digital computation. Conformity between this description and the experimental data obtained from the literature was explored by automatic searches for the sets of rate constants that yielded statis tical best-fits to the experimental data. Fits were obtained from rena l epithelial cell lines, HeLa cells, and duck erythrocytes. Results sh ow that the reaction cycle for the Na-K-2Cl cotransporter conforms wel l, quantitatively, with the experimental data.