TABLE 4

Effects of cytoplasmic (cyto) or mitochondrial (mito 1 and 2) catalase overexpression in insulin-producing RINm5F cells on the glucose oxidation rate after exposure to IL-1β alone or a cytokine mixture

Cell clonesGlucose oxidation (% of untreated cells)
IL-1βCytokine mixture
Control34 ± 3 (8)38 ± 3 (7)
Cyto53 ± 3 (8)58 ± 4 (8)
Mito 135 ± 4 (8)36 ± 3 (8)
Mito 2128 ± 6 (12)*139 ± 7 (11)*
  • Data are means + SE (no. experiments). Insulin-producing RINm5F cell clones overexpressing catalase in the cyto and mito 1 and 2 and control cells were incubated for 72 h with IL-1β (600 units/ml) alone or with the 1 × cytokine mixture (60 units/ml IL-1β, 185 units/ml TNF-α, and 14 units/ml IFN-γ). Glucose oxidation rates at 10 mmol/l [U-14C]glucose (1 Ci/mol) were expressed as the percentage of untreated cells. Glucose oxidation rates under control conditions were the same in the control clone and in the mito 1 and 2 clone but significantly lower (P < 0.01) in the cyto clone (glucose oxidation rate, expressed in mmol · g DNA −1 · h−1: control, 0.126 ± 0.006; cyto, 0.099 ± 0.004; mito 1, 0.108 ± 0.003; mito 2, 0.113 ±0.005).

  • *

    * P < 0.001 vs. control clone.