There's another thread going right now about re-raising AK in position and out of position. In that thread, it's pretty much agreed that if you're out of position and re-raise AK, you're pretty much obligated to bet the flop. I agree with them too. I think you need to bet this flop and fold to a raise (obviously).
KoW
Edit: Here's the thread
Re-raise AK Preflop?