Mediates electroneutral potassium-chloride cotransport when activated by cell swelling (PubMed:35759661). May contribute to cell volume homeostasis in single cells (PubMed:10913127, PubMed:34031912). May be involved in the regulation of basolateral Cl(-) exit in NaCl absorbing epithelia (By similarity). {ECO:0000250|UniProtKB:Q9JIS8, ECO:0000269|PubMed:10913127, ECO:0000269|PubMed:34031912, ECO:0000269|PubMed:35759661}. [Isoform 4]: No transporter activity. . This is the function of SLC12A4 (solute carrier family 12 member 4, Ensembl gene identifier ENSG00000124067).