Radial deformations strongly affect the electronic structure of carbon nanotubes. We analyze the wave functions in the (9, 0) and the (5, 5) nanotubes and find that the variation of subbands with radial deformation depends on the wavevector and the helicity. In metallic nanotubes local radial deformations provide internal barriers to electron transport while in small-gap nanotubes they induce a metallic transition.