Catalase Protects Cardiomyocyte Function in Models of Type 1 and Type 2 Diabetes
Article Figures & Tables
Figures
- FIG. 1.
Catalase RNA levels are increased in OVE26 hearts. Northern blots were prepared from total RNA of 5-month-old animals using eight OVE26 and seven FVB hearts. The lower graphs show the intensity of signals for catalase normalized to the intensity of the signal for GAPDH. *OVE26 is different from FVB by P < 0.01. Vertical bars indicate SE.
- FIG. 2.
Overexpression of catalase protects against morphologic damage. Electron micrographs of left ventricle in FVB (A), OVE26 (B), and OVE26C (C) mice at 5 months of age. D: Semiquantitative, blind, scoring of 32 randomly selected electron micrographs from each of two or three FVB, OVE26 diabetic, and OVE26C mice at 5 months. Higher magnification showing typical FVB mitochondria (E) and severely damaged OVE26 mitochondria (F). G: Portion of OVE26 left ventricle with normal myofibrils and damaged mitochondria. *OVE26 differs from OVE26C and FVB, P < 0.001.
- FIG. 3.
The catalase transgene protects cardiomyocyte contractility. A: Percent peak shortening. B: Rates of contraction (+dL/dt) and relaxation (-dL/dt). *OVE26 is different from FVB and OVE26C, P < 0.01. Values are the means from ≥60 myocytes derived from at least five mice per group. The mean value obtained from at least five contractions was obtained each cardiomyocyte. Vertical bars indicate SE.
- FIG. 4.
Catalase does not prevent slower calcium reuptake in OVE26 myocytes. *Time required for calcium to return to 90% of baseline is longer in OVE26 and OVE26C myocytes, P < 0.01. Values are the means from ≥80 myocytes derived from four mice per group. The mean value obtained from at least five contractions was obtained for each cardiomyocyte. Vertical bars indicate SE.
- FIG. 5.
Western blot of MDA-modified proteins in FVB control, OVE26 diabetic, and catalase-protected OVE26C diabetic hearts. The intensity of the 50-kDa protein on this blot was elevated 2.5-fold in OVE26 samples (P < 0.02) compared with FVB samples. The intensity of FVB and OVE26C immunostaining was not significantly different. MDA-modified proteins were recognized with polyclonal goat anti-MDA antibody and visualized with peroxidase-conjugated anti-goat antibody. Statistical analysis was performed by ANOVA and Tukey’s post hoc test with three animals per group. Band intensities were normalized to β-actin intensity.
- FIG. 6.
Catalase reduces high-glucose-induced ROS production in diabetic myocytes. A: Isolated cardiomyocytes were exposed to normal glucose media (5.5 mmol/l) or high-glucose media (25 mmol/l) for 60 min, and ROS was measured by CM-H2DCFDA fluorescence. *OVE26 exposed to high glucose was greater than all other groups (P < 0.01); #OVE26C was greater than all other groups except OVE26 exposed to high glucose and OVE26C exposed to normal glucose (P < 0.05). Vertical bars indicate SE. B and C: Typical fluorescence images of OVE26 myocytes exposed to high glucose (B) or low glucose (C). The arrows point to the fluorescence standardization bead used to normalize the intensity of all images. hg, high glucose; ng, normal glucose.
- FIG. 7.
Rotenone and thenoyltrifluoroacetone inhibit high-glucose-stimulated ROS production in diabetic OVE26 cardiomyocytes. *P < 0.01 vs. all other groups. Values are the means from 100 myocytes derived from four mice per group. Vertical bars indicate SE. hg, high glucose (25 mmol/l); ng, normal glucose (5.5 mmol/l); ROT, rotenone (5 μmol/l); TTFR, thenoyltrifluoroacetone (10 μmol/l).
- FIG. 8.
The catalase transgene protects myocytes contractility in Ay diabetes. A: Percent peak shortening. B: Rates of contraction (+dL/dt) and relaxation (-dL/dt). *Ay diabetic myocytes are different from FK control and AyC myocytes, P < 0.01. Values are the means from ≥120 myocytes derived from five or six mice per group. Vertical bars are the SE.
In this Issue
