CATION-TRANSPORT IN MOUSE ERYTHROCYTES - ROLE OF K-CL- COTRANSPORT INREGULATORY VOLUME DECREASE()

We investigated cation transport and cell volume regulation in erythro cytes of CD1 and C57/B6 mice. Swelling of cells from either strain sti mulated K+ efflux that was insensitive to ouabain, bumetanide, and clo trimazole. Seventy-five percent of swelling-induced K+ efflux was Cl- dependent (inhibited by sulfamate or methanesulfonate, partially by NO 3-, but not by SCN-) and was inhibited by okadaic acid (OA; 50% inhibi tory concentration = 18 +/- 6 nM in CD1 and 10 +/- 4 nM in C57/B6). In both strains, K+ efflux into isotonic medium was stimulated by stauro sporine or by N-ethylmaleimide, and the latter was partially blocked b y pretreatment of cells with OA. When cells of either strain were incu bated in hypotonic medium or preswollen isosmotically with nystatin, O A-sensitive regulatory volume decrease (RVD) and K+ loss were observed . RVD produced by hypotonic swelling was prevented by Cl- replacement with sulfamate or methanesulfonate. These properties suggest the prese nce in outbred and inbred mouse erythrocytes of RVD mediated by K+-Cl- cotransport.