  We have carried out a set of self-consistent N-body simulations to study the
interaction between disc galaxies and merging satellites with the aim of
determining the disc kinematical changes induced by such events. We explore a
region of the parameter space embracing satellites with different masses and
internal structure and orbits of various eccentricities. We find that the
analyt ic estimates of T\'oth and Ostriker (1992) are high; overestimating the
disc heating and thickening resulting from the accretion process by a factor of
about 2-3. We find that the heating and thickening of the disc differ for
satellites on prograde and retrograde orbits. The former tend to heat the
stellar disc while the latter primarily produce a coherent tilt. Thus, disc
galaxies may accrete quite massive satellites without destroying the disc,
particularly, if the orbits are retrograde. We also find that a massive bulge
may play a role in reducing these effects. We have quantified the importance of
the responsiveness of the halo by replacing it by a rigid potentia l in several
simulations. In these cases, the increase of the vertical scale length is
larger by a factor of $1.5-2$, indicating that a self-consistent treatment is
essential to get realistic results. A frequent by-product of the accretion
process is the formation of weak stellar warps and asymmetric discs. Finally,
we have checked how well Chandrasekhar's dynamical friction formula reproduces
the sinking rates in several of our experiments. We find that it works well
provided a suitable value is chosen for the Coulomb logarithm and the satellite
mass is taken to be the mass still bound to the satellite at each moment.
