Ca(2+)(out) + 3 Na(+)(in) => Ca(2+)(in) + 3 Na(+)(out)
ca(2+)(out) + 3 na(+)(in) => ca(2+)(in) + 3 na(+)(out)
Ca(2+)(out) + 3 Na(+)(in) => Ca(2+)(in) + 3 Na(+)(out)
ca(2+)(out) + 3 na(+)(in) => ca(2+)(in) + 3 na(+)(out)