PPARγ-Independent Side Effects of Thiazolidinediones on Mitochondrial Redox State in Rat Isolated Hearts

Figure 1. Shows the experimental protocols. The hearts were isolated from eight-week-old male Brown Norway rats and mounted in a Langendorff setup. After 20 min equilibration and a baseline (bl) reading, the hearts in the first set of experiments (n = 12; Panel (A)) were given rosiglitazone (Rosi, 50 µM) or a vehicle (Con) for two times, 5 min each with a 5 min washout period interspersed and followed by 15 min washout before 30 min of global no-flow ischemia and 120 min of reperfusion (IR) and subsequent infarct size (IS) determination. In a second set of experiments (Panel (B)), the hearts were given increasing concentrations (2, 10, and 50 µM) of either rosiglitazone (Rosi, blue colors; n = 6) or pioglitazone (Pio, red colors; n = 6) for 5 min each followed by 30 min washout. This series was repeated in the presence of 10 µM of the PPARγ antagonist GW9662 (GW, white). The hearts were not subject to IR or to IS determination.

Figure 2. Shows representative time courses of NADH (closed blue circles) and FAD (open green diamonds) autofluorescence for an experiment with rosiglitazone (Rosi) in increasing doses from 0 to 50 µM (5 min each) first in the absence and then, after a 30 min washout period, in the presence of the PPARγ antagonist GW9662 (GW, 10 µM).

Figure 3. Shows a concentration-dependent decrease in autofluorescence of reduced NADH (Panel (A)) and a concomitant concentration-dependent increase in autofluorescence of oxidized FAD (Panel (B)) with administration of the thiazolidinediones (TZDs) rosiglitazone (Rosi, open dark-blue square) and pioglitazone (Pio, closed red square) compared to % baseline (bl). The PPARγ antagonist GW9662 (GW, 10 µM) did not alter the effect of rosiglitazone (open light-blue triangle) or pioglitazone (closed pink triangle) on NADH (Panel (A)) or FAD (Panel (B)) at any of the concentrations. Statistics: ANOVA followed by SNK post-hoc test with P < 0.05 (two-tailed) vs. * 0 µM TZD; n = 6 per group. Please note that the slight horizontal offset of curves for any given concentration is for visual purposes only.