  We investigated magnetic, magnetotransport and magnetostriction properties of
the A-type antiferromagnet Pr$_{0.46}$Sr$_{0.54}$MnO$_3$ which undergoes a
first order paramagnetic-antiferromagnetic transition below T$_N$ = 210 K while
cooling and T$_N$ = 215 K while warming. The zero field ($\mu_0$H = 0 T)
resistivity shows a sudden jump at T$_N$ and a small bump around T$_{max}$ =
220 K (\TEXTsymbol{>} T$_N$). T$_N$ shifts down and T$_{max}$ shifts up with
increasing $\mu_0$H. Magnetoresistance as high as -45-57 % at 7 T is found in
the temperature range 180 K-230 K. Isothermal measurements indicate that the
field induced antiferromagnetic to ferromagnetic transition below T$_N$ is
accompanied by a rapid decrease of the resistivity but increase of volume
($\Delta $V/V = +0.25 % at 180 K and 13.7 T). This lattice coupled
magnetoresistance transition is suggested due to the field induced structural
transition from the low volume orthorhombic to the high volume tetragonal
structure.
