Sodium exporter that functions mainly at alkaline pH (PubMed:8496184, PubMed:9518629, PubMed:8021217). Can also function as a potassium/proton and calcium/proton antiporter at alkaline pH (PubMed:8496184, PubMed:16687400, PubMed:8021217, PubMed:18342619). Does not play a major role in calcium export (PubMed:18342619). The K(+)/H(+) antiporter activity may enable E.coli to adapt to K(+) salinity stress and to maintain K(+) homeostasis (PubMed:16687400). H(+)(out) + Na(+)(in) = H(+)(in) + Na(+)(out) H(+)(out) + K(+)(in) = H(+)(in) + K(+)(out) Ca(2+)(in) + H(+)(out) = Ca(2+)(out) + H(+)(in) Pronounced pH dependence with sodium as substrate (PubMed:8496184). Ca(2+)/H(+) and Na(+)/H(+) antiporter activities are both inhibited by magnesium (PubMed:8496184). Ca(2+)/H(+) activity is inhibited by the proton ionophore carbonyl cyanide m-chlorophenylhydrazone (CCCP) (PubMed:8496184). Belongs to the Ca(2+):cation antiporter (CaCA) (TC 2.A.19) family.