  A hot plasma is the dominant phase of the interstellar medium of early-type
galaxies. Its origin can reside in stellar mass losses, residual gas from the
formation epoch, and accretion from outside of the galaxies. Its evolution is
linked to the dynamical structure of the host galaxy, to the supernova and AGN
feedback, and to (late-epoch) star formation, in a way that has yet to be fully
understood. Important clues about the origin and evolution of the hot gas come
from the abundances of heavy metals, that have been studied with increasing
detail with XMM-Newton and Chandra. We present recent high resolution
hydrodynamical simulations of the hot gas evolution that include the above
processes, and where several chemical species, originating in AGB stars and
supernovae of type Ia and II, have also been considered. The high resolution,
of few parsecs in the central galactic region, allows us to track the metal
enrichment, transportation and dilution throughout the galaxy. The comparison
of model results with observed abundances reveals a good agreement for the
region enriched by the AGN wind, but also discrepancies for the diffuse hot
gas; the latter indicate the need for a revision of standard assumptions,
and/or the importance of neglected effects as those due to the dust, and/or
residual uncertainties in deriving abundances from the X-ray spectra.
