Figure 1.

Hypoxia induces ceramide production by the activation of nSMase. (A) Top panel: time course of the decay in O₂ as measured by a Clark electrode in the chamber. Medium panel: cellular ceramide content determined by immunostaining of PASMC with a monoclonal ceramide-specific antibody 15B4. Bottom panel: representative pictures of immunostained cells after 0, 1, 3, and 5 min of hypoxia. (B) Effects of 10 µmol/L GW4869 (GW) and 10 µmol/L desipramine, inhibitors of nSMase and aSMase, respectively, on ceramide production stimulated by 3 min hypoxia. Results are means ± SEM (averaged FITC-fluorescence intensity relative to cell surface measured in three to four coverslips with at least 10 cells each), # indicates P < 0.05 normoxia vs. hypoxia (unpaired t-test), **indicates P < 0.01 vs. control (ANOVA followed by a Bonferroni's test).