Depletion of cardiac norepinephrine but not brain catecholamines by MPTP-N-oxide in mice.

After a single dose in mice, MPTP-N-oxide caused a dose-dependent depletion of cardiac norepinephrine which was similar although less pronounced than that caused by MPTP itself. After repeated daily doses, MPTP-N-oxide depleted cardiac norepinephrine, but did not deplete norepinephrine in the frontal cortex or dopamine in the striatum of mice. MPTP-N-oxide differed from MPTP, which depleted cardiac norepinephrine, cortical norepinephrine and striatal dopamine after repeated daily doses, but was similar to MPP+, another metabolite of MPTP, which depleted only cardiac norepinephrine. These data suggest that MPTP-N-oxide may contribute to the peripheral catecholamine-depleting effects after MPTP injection.