  We study the effects of time-dependent mass injection and heating on the
evolution of the interstellar medium (ISM) in elliptical galaxies. As the large
and luminous ellipticals have supermassive black holes at their cores, which
were probably much less massive in the young universe, feeding these black
holes is essential. We examine steady state solutions and describe the impact
of the initial starburst on the evolution of the ISM and consequences for
galactic activity, based on results from Starburst99.
