  We present evidence for changes in the strength and profile of the iron
K-alpha line in Active Galactic Nuclei (AGN), based on X-ray observations with
ASCA. There is a clear decrease in the strength of the line with increasing
luminosity. This relation is is not due solely to radio power, as it persists
when only radio-quiet AGN are considered and therefore cannot be fully
explained by relativistic beaming. In addition to the change in strength, the
line profile also appears to be different in higher luminosity sources. We
discuss these results in terms of a model where the accretion disk becomes
ionized as a function of the accretion rate.
