  We re-analyze the physical conditions for Magneto-rotational Instability
(MRI) within a steady axisymmetric stratified disk of plasma, in order to
account for the so-called isorotation theory (the spatial profile of
differential angular velocity depends on the magnetic flux surface). We develop
the study of linear stability around an astrophysical background configuration,
following the original derivation in \cite{Ba:1995}, but implementing the
isorotation condition as the orthogonality between the background magnetic
field and the angular velocity gradient. We demonstrate that a dependence on
the background magnetic field direction is restored in the dispersion relation
and, hence, the emergence of MRI is also influenced by field orientation.
