The parallel effects of the anion transport inhibitor DIDS (4,4'-diisothiocyanostilbene-2,2'-disulfonate) on net chloride flow and on chloride exchange suggest that a major portion of net chloride flow takes place through the anion exchange system . The "slippage" model postulates that the rate of net any change in transport site conformation such as normally occurs during the anion exchange process . This model is successful in predicting that the anion exchange inhibitor NAP-taurine, which binds to the modifer site and inhibits the conformational change, has less effect on net chloride flow than on chloride exchange .