  Modifications of Special Relativity by the introduction of an invariant
energy and/or momentum level (so-called Doubly Special Relativity theories,
DSR) or by an energy-momentum dependence of the Planck constant (Generalized
Uncertainty Principle, GUP) are compared with classical gravitational effects
in an interaction processes. For the low energy limit of the usual formulations
of DSR to be equivalent with Newtonian gravity, a restrictive condition is
found. GUP yields an effective repulsion, in analogy to the gravitational
repulsion in loop quantum cosmology.
