sodium:proton antiporter activity regulation of cardiac muscle cell membrane potential obsolete sodium:proton antiporter activity involved in regulation of cardiac muscle cell membrane potential https://github.com/geneontology/go-ontology/issues/31254 true This term was obsoleted because it is a pre-composed term that should be captured as a GO-CAM model. GO:0086040 molecular_function tb 2011-11-11T03:33:44Z OBSOLETE. Enables the transfer of a solute or solutes from one side of a cardiac muscle cell membrane to the other according to the reaction: Na+(out) + H+(in) = Na+(in) + H+(out). This transfer contributes to the regulation of the cardiac muscle cell plasma membrane potential. sodium:hydrogen antiporter activity involved in regulation of cardiac muscle cell membrane potential