N,N′-bis(2-Mercaptoethyl)isopthalamide (NBMI) attenuates the oxidant-induced phospholipase D (PLD) activation in mouse aortic endothelial cells (MAECs). The MAECs (5 × 105 cells/35 mm dish) were labeled with [32P]orthophosphate in phosphate-free Dulbecco-modified Eagle medium (DMEM) for 12 hours. Following [32P]orthophosphate labeling, cells were pretreated with minimal essential medium (MEM) alone or MEM containing different concentrations (10, 25, and 50 μmol/L) NBMI for 1 hour. Following NBMI pretreatment, cells were treated with 4-hydroxy-2-nonenal ([4-HNE] 100 μmol/L; A) or diperoxovanadate ([DPV] 10 μmol/L; B) for 1 hour in the presence of 0.05% (volume/volume [vol/vol]) 1-butanol. At the end of the incubation period, [32P]phosphatidylbutanol ([32P]PBt) formed was determined. Data represent mean ± standard deviation (SD) calculated from 3 independent experiments. *Significantly different at P < .05 as compared to cells treated with MEM alone. **Significantly different at P < .05 as compared to cells treated with MEM containing oxidant alone.