Abstract 19633: Downregulation of Endothelial Derived Hyperpolarizing Factors in ob-/ob- Rat Hearts
Introduction: Diabetes mellitus is associated with endothelial dysfunction and which is believed to result in impaired regulation of vasoconstrictors and vasodilators. Cytochrome P450 (CYP) epoxygenase and its metabolites has been considered as endothelium derived hyperpolarizing factor (EDHF) involved in the pathogenesis of obesity and hypertension. Suppression or induction of an endothelium-derived CYP-generated metabolites contribute to endothelium-dependent vasodilatation. But, it was not well described expression of CYP and its metabolites in diabetic rat heart.
Methods: Otsuka Long Evans Tokushima Fatty (OLETF) and Long Evans Tokushima Otsuka (LETO) were used of type II diabetes animal model with obesity. LETO (n=7) and OLETF rats (n=7) were started to intake high glucose diet and administrated CYP inhibitor, chloramphenicol (CAP, 300 mg/kg/day) for 2 weeks at age of 22 weeks. Expression of CYP2C23, 2J3 and CYP4A1 were detected by western blot and RT-PCR and their metabolites (EETs) were measured by liquid chromatography mass spectrometry (LC/MS) in ob-/ob- rat heart microsomes.
Results: The body weight and blood glucose level were increased steadily and reached plateau at 20 weeks (LETO vs OLETF ; 126 ± 8 vs 315 ± 48 mg/dL). The expression of CYP2J3 protein and mRNA were markedly decreased, whereas the expression of CYP2C23 were increased in OLETF rats compared with LETO rats (100 ± 2.5 % vs 56.78 ± 7.20 % * P< 0.01). The expression of CYP2J3 was recovered in OLETF by CAP treatment (68.41 ± 10.4 % vs 102.2 ± 6.5 %, P<0.01). In LC/MS, although no differences were detected in 5,6-, 8,9-, 14,15 -EET between LETO and OLETF, the level of 11,12-EET was decreased significantly in OLETF and recovered by CAP treatment.
Conclusion: CYP2J3 is downregulated and CYP2C23 is upregulated in ob-/ob- rat hearts. CAP treatment reverses CYP epoxygenase protein and mRNA expression, as well as its metabolite 11,12-EET activity in obese diabetic rat hearts.
- © 2010 by American Heart Association, Inc.