Enables the active transport of a solute across a membrane by a mechanism whereby two or more species are transported in opposite directions in a tightly coupled process not directly linked to a form of energy other than chemiosmotic energy. The reaction is: solute A(out) + solute B(in) = solute A(in) + solute B(out). [ http://www.ncbi.nlm.nih.gov/pubmed/10839820 GOC:mtg_transport https://www.worldcat.org/search?q=bn%3A0815340729 ]