Figure 1.

Scavenging superoxide inhibits apoB100 degradation induced by DHA and decreases the level of lipid peroxides. McA cells were treated with BSA or DHA/BSA complexes (DHA) in the presence (+) or absence (−) of the SO scavenger MnTBAP. ApoB100 recovery from cell lysate and medium samples was determined in a pulse-chase protocol to assess degradation of newly synthesized protein (see Materials and Methods). A) Representative fluorogram of secreted apoB100 at 90 min of chase. Doublets in this and other fluorograms represent apoB100 and the apoB95 forms that are secreted by rat hepatic cells. apoB95 form is derived from the apoB100 by proteolytic processing just before secretion (26), and its abundance was included in the recovery data for apoB100. B) Fluorograms were scanned in a densitometer; quantitative apoB100 recovery data are displayed. Histogram represents mean ± se (n=3) apoB100 recovery of 3 independent experiments. **P < 0.01. C) Lipid peroxidation was measured at different time points in the presence of DHA with (▴) or without (■) MnTBAP and is expressed as a fold increase of the initial amount of MDA measured at t = 0 in cells untreated. Data represent 3 independent experiments.