Multiple effects of the phenylhydrazone derivative FCCP on the secretory pathway in rat plasma cells

We studied the sensitivity of the last steps of the secretory process of antibody-producing cells to carbonylcyanide-p-trifluoromethoxyphenylhydrazone (FCCP) and sodium azide (NaN3), agents which lower the cellular ATP content by inhibiting oxidative phosphorylation and mitochondrial electron transport, respectively. Popliteal lymph node cells or purified plasma cells from rats immunized against horseradish peroxidase were incubated with the drugs. The rate of secretion of anti-HRP antibodies was measured by an enzyme-linked immunoadsorbent assay or after biosynthetic labeling with L-[3H]fucose. FCCP as well as NaN3 were shown to rapidly inhibit (in less than 5 min) the secretion of immunoglobulins (Ig) and to partially block the release of fucosylated Ig. This indicates that the drugs inhibit the transport of Ig from the Golgi apparatus (GA) (where fucose is added to Ig) to the plasma membrane. However, the degree of inhibition reached 40 to 50% with NaN3 and 70 to 80% with FCCP, whereas both drugs similarly depleted ATP stores by 45 to 55%. These results are consistent with multiple effects of FCCP on the secretion pathway of Ig. As a tentative explanation, we suggest that FCCP, because of its protonophore properties, not only reduces cellular ATP levels but may also neutralize the Golgi or post-Golgi acidic compartments recently shown to be involved in the transport of plasma membrane and secretory proteins.