il\VOLVEMENT OF RETII\OIC ACID II{ - MSpace at the University of ...

IIYPOTHESIS
This study tests the hypothesis that oxidative stress induced apoptosis and heart
failure due to adriamycin may be mediated by changes in the RAR/RXR receptor ratio'
This study followed a two prong approach, involving in vivo and in vitro
experiments. For the in vlvo studies, heart failure due to adriamycin was produced in rats
with or without probucol, a proven lipid soluble antioxidant. For the in vitro studíes, adult
ventricular myocytes were isolated and exposed to different doses of adriamycin (4, 8 and
10pM) and retinoic acid (0.1 and 1pM) in different combinations. In these studies, trolox
(20pM) a water soluble antioxidant was also used. After the appropriate incubation
period, the cells were harvested and used. Following data were obtained using the whole
hearts as well as isolated myocytes:
1. Hemodynamic assessment of control, adriamycin, adriamycin*probucol and
probucol group animals;
2. The expression of retinoic acid receptors, RAR (o,Þ,Y) and RXR (o,B,y)in the hearts
as well as myocytes;
3. The RAR/RXR receptor ratio in the hearts as well as myocytes;
4. The expression of peroxisome activation receptor delta (PPAR ô) in the hearts as
well as isolated myocytes;
5. The levels of anti and pro-apoptotic (Bax) and antiapoptotic (Bcl-xl) proteins in the
hearts and isolated myocYtes;
6. The BaxlBcl-xl ratio in the hearts as well as isolated myocytes;
7. Apoptosis in the isolated myocytes using the Propidium Iodide+ Annexin staining;
8. Study of oxidative stress in isolated adult cardiac myocytes using an
immunoflourescence technique (CM-H2 DCFDA).
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