Author + information
- SangJin Kim,
- Xiao Lei Gao,
- LaeYoung Jung,
- YiShik Kim,
- Hae-Eun Yun,
- SunHwa Lee,
- SangRok Lee,
- Won Ho Kim,
- JaeKi Ko and
- Jei Keon Chae
Intracellular accumulation of Ca2+ during ischemia / reperfusion (I/R) injury results in the activation of Ca2+-dependent enzymes such as calpain. Calpain induces proteolysis of RXRα in the nuclear extracts, which prevents RXR and PPAR-α heterodimer formation and gene transcription of cytochrome P450 (CYP) epoxygenases. Epoxyeicosatrienoic acids (EETs), generated by CYP2J3, also showed a critical role in protecting myocardial I/R injury in some studies using CYP-modulators such as chloramphenicol (CAP). Here, we examined the effects of calpain on the activity of CYP epoxygenase and 11,12-EET in I/R injured rat hearts.
I/R injury of rat hearts was induced by 45 minutes no-flow ischemia and 45 minutes reperfusion in Langendorff model (n=5, each group). Calpain inhibitor and CAP were added to the perfusion buffer 20 min before I/R. LDH release was determined by restoring flow 30 min after reperfusion and infarct size was assessed by TTC staining. Calpain, RXR-α, PPAR-α and a heart specific CYP epoxygenase CYP2J3 were determined by western blotting and RT-PCR. 11,12-EET was measured by liquid chromatography-mass spectrometry.
I/R injury provoked Ca2+-dependent calpain expression which was significantly associated with reduced RXRα, PPAR-α and CYP2J3 expression. In accordance with CYP2J3 expression, 11,12-EETs were also reduced by I/R injury. Administration of CAP as CYP modulator reduced the calpain expression, which was manifested with the recovery of RXRα, PPAR-α and CYP2J3 expression in I/R injured rat hearts. Increased level of 11,12-EET by CAP was closely related with significant reduction of LDH release and infarct size.
Calpain was up-regulated during I/R injury resulting in the decrease of RXRα, PPAR-α and CYP2J3. CAP reversed the expression of RXRα, PPAR-α and CYP2J3. The up-regulation of CYP2J3 is attributed by RXRα and PPAR-α heterodimer formation and gene transcription. These data suggested that the inhibition of calpain by CAP has a cardioprotective role through the up-regulation of CYP2J3 expression and 11,12-EETs generation.
Poster Sessions, Expo North
Saturday, March 09, 2013, 3:45 p.m.-4:30 p.m.
Session Title: Novel Therapeutic Targets in Hearts Failure
Abstract Category: 16. Heart Failure: Basic
Presentation Number: 1176-293
- 2013 American College of Cardiology Foundation