The belly of the plane is at the same pressure as the cabin (otherwise the passenger floor would have to be pressure-tight, and the symmetry of pressurization forces on the aluminum tube hurtling through the sky would be lost). So, if cans don't blow up on the flight attendant drink carts, they don't blow up in the luggage hold. Now if the baggage handlers drop-kick your suitcase onto a spike you may have problems...