acetylcholine(in) + 2 H(+)(out) => acetylcholine(out) + 2 H(+)(in)
acetylcholine(in) + 2 h(+)(out) => acetylcholine(out) + 2 h(+)(in)
acetylcholine(in) + 2 H(+)(out) => acetylcholine(out) + 2 H(+)(in)
acetylcholine(in) + 2 h(+)(out) => acetylcholine(out) + 2 h(+)(in)