thymine(out) + Na(+)(out) <=> thymine(in) + Na(+)(in)
thymine(out) + na(+)(out) <=> thymine(in) + na(+)(in)
thymine(out) + Na(+)(out) <=> thymine(in) + Na(+)(in)
thymine(out) + na(+)(out) <=> thymine(in) + na(+)(in)