D-branes and T-duality

We show how the T-duality between D-branes is realized (i) on p-brane solutions (p = 0,..., 9) of IIA/IIB supergravity and (ii) on the D-brane actions (p = 0,..., 3) that act as source terms for the p-brane solutions. We point out that the presence of a cosmological constant in the IIA theory leads, by the requirement of gauge invariance, to a topological mass term for the worldvolume gauge field in the 2-brane case.