Catalyzes both the uptake and excretion of putrescine. The uptake of putrescine is dependent on the membrane potential and the excretion involves putrescine-ornithine antiporter activity. H(+)(in) + putrescine(in) = H(+)(out) + putrescine(out) L-ornithine(out) + putrescine(in) = L-ornithine(in) + putrescine(out) Belongs to the amino acid-polyamine-organocation (APC) superfamily. Basic amino acid/polyamine antiporter (APA) (TC 2.A.3.2) family.