Figure 6. A role for uncoupling proteins (UCPs) for the diminished contractile reserve in TGF-β₁ transgenic mice.

(A) Stimulation of rat cardiac myocytes with TGF-β₁ (10 ng/ml) leads to upregulation of UCP2 and UCP3 mRNA (n = 4 in each group). (B) Western blot analysis of UCP3 expression in mitochondria isolated from myocardial tissue of WT and TGF-β₁ mice. COX-I served as a loading control, and UCP3 knockout mice served as a negative control. The bar graph represents means ± SEM from 7 animals in each group. (C and D) Expression of UCP2 and UCP3 mRNA in the various treatment groups. (E) Functional role of UCPs in the heart. Inhibition of UCPs by genipin (100 mg/kgBW) restored the contractile response to dobutamine (40 µg/kg/min) in TGF-β₁ mice. (F) Genipin (5 µM) restored the contractile response to isoprenaline (10 µM) in isolated cardiac myocytes (n = 26–30 in each group).