In K522R, the Lys-522 has been converted to Arg by site-directed mutagenesis, thus preventing covalent binding of H2DIDS. □, K522R; ▪, K522R in presence of 5 × 10−5m H2DIDS; , covalent binding of H2DIDS to K522R. Measurements at day 5 post-injection. Bars represent means ±s.e.m.; n = 8. A, chloride exchange activity; B, anion conductance; C, lithium influx.