Poster Display III. Animal models and experimentation Sunday, 10 June 2007 81 expression in the LVFW caused abnormal ECG including T wave inver- sion and ST-segment reversion. In Hop-transfected and control groups, there was no change in ECG parameters from gene delivery to final stud- ies, nor were there differences in mean LVESP between these groups. In all animals, LVEDP values were the same regardless of whether Myoc- containing or other plasmids were delivered into myocardium. Conclusions: Given that heart failure is accompanied by increase in Myoc expression, this work demonstrates for the first time that in-vivo induced increase in Myoc expression can result in impared ventricular contraction. 353 Regulation of PPAR and PPAR target genes in myocardial infarction in rats D. Fliegner 1 , E. Becher 1 , C. Schubert 1 , D. Westermann 1 , A. Riad 1 , C. Tschöpe 1 , V. Regitz-Zagrosek 2 1 Charite Berlin, Center for Cardiovascular Research, Berlin, Germany; 2 German Heart Institut, Berlin, Germany Background: The Peroxisome proliferator-activated receptors (PPARs) represent a central switch point for cardiac energy metabolism. We tested the hypothesis, that PPARs are regulated in myocardial infarction (MI) and the target genes, too. Since angiotensin receptor blockers (ARB) influence PPARγ dependent gene transcription, we also determined the effects of the ARB Irbesartan (IRB). Methods: Experimental MI was performed in male Sprague Dawley rats, treated with placebo or IRB for three weeks. Hemodynamic measure- ments were performed in all animals. Western Blot and/or Real Time- PCR analysis was done for all PPARs and major PPAR target genes such as CPT1, CD36 (fatty acid transporter protein/translocase), MCAD (Medium Chain Acetyl-CoA-Dehydrogenase) and ACO (Acetyl-CoA- Oxidase) and the glucose transporters GLUT1, GLUT4 and the fibrosis related gene CTGF within the infarcted and non-infarcted area. Cellular localization of PPARγ was documented by immunofluorescence. Results: MI decreased LVP and dp/dt max and increased LVEDP, coun- teracted by IRB. PPARγ protein content was increased to 175% in the area of MI, but remained unchanged in non-infarcted areas. PPARγ in- crease was localized to myocytes and to fibroblasts in the MI area. This effect was not altered by IRB. PPARα and PPARβ/δ protein expression was not affected by MI and not altered by IRB. The mRNA expression of fatty acid metabolizing enzymes CPT-1, CD36, MCAD, ACO, Malonyl- CoA and the genes encoding for the glucose transporter GLUT4 were significantly downregulated (all p<0.05) in infarcted tissue, which was unaffected by IRB. The gene expression of CD36 and ACO in the non- infarcted areas of the hearts was unchanged by MI but upregulated by IRB to 120% and 160%, respectively. CTGF mRNA expression was increased ten fold in the area of infarction (p<0,005). Conclusion: In the infarcted area expression of PPARγ, but not PPARα or PPARβ/δ, is enhanced, without an increase of fatty acid oxidation or glucose transport. Since an increase of PPARγ on fibroblasts and of CTGF was observed we speculate that PPARγ might regulate fibrosis post MI. 354 Trimetazidine improves post-ischemic recovery by preserving endothelial nitric oxide synthase expression in isolated working rat hearts P. Di Napoli 1 , A. Grilli 2 , A.A. Taccardi 2 , M. Felaco 1 , A. Barsotti 3 1 Villa Pini d’Abruzzo Clinic, Lab. Exp. Cardiology, Dept. Clinical Sciences, Chieti, Italy; 2 University of Chieti, Department of Biomorphology, Biology Section, Chieti, Italy; 3 University of Genoa, Department of Cardiology, Genoa, Italy Previous studies have consistently shown that the piperazine deriva- tive trimetazidine (TMZ, 1-[2,3,4-trimethoxybenzil] piperazine, dihydro- cloride) exerts beneficial effects in patients with heart failure and in ex- perimental ischemia-reperfusion models. We tested the hypothesis that cardioprotective effect of TMZ is partly mediated by preservation of the endothelial barrier of the coronary microcirculation. Methods: Isolated Wistar rat (250-300 g) hearts were subjected to a 15 min period of global ischemia and 180 min reperfusion in the presence or absence of 1 μM TMZ. Hemodynamic parameters, heart weight, cre- atinekinase (CK) release and microvascular permeability (FITC-albumin extravasation) were evaluated. In addition, eNOS gene expression was estimated by rt-PCR, and eNOS protein levels were assessed by West- ern analysis. In order to confirm the involvement of NO in mediating the cardioprotective effects of TMZ, 30 μM N-Nitro-L-Arginine methylester (L-NAME), a specific inhibitor of nitric oxide synthase, was used. Results: After ischemia and reperfusion, TMZ produced a significant improvement of mechanical function associated with a reduction of CK release and FITC-albumin diffusion (P<0.001); the agent also resulted in improvement in coronary flow (at 45 min + 27% vs control). The e-NOS mRNA and protein levels were significantly higher in TMZ-treated hearts compared to controls. The addition of L-NAME significantly reduced the beneficial effects of TMZ on contractile function, CK release and FITC- albumin diffusion. Conclusions: in the isolated rat heart, TMZ exerts a relevant, NO- dependent, cardioprotection against ischemia-reperfusion injury and pre- serves the endothelial barrier of the coronary circulation. This could contribute to explain the cardioprotective action of TMZ following is- chemia and reperfusion and could explain, at least in part, the beneficial effects of this drug in patients with ischemic dilated cardiomyopathy and ventricular dysfunction. 355 Plasma membrane calcium ATPase isoform 4 as a potential drug target for treatment during hypertrophy E. Cartwright, F. Baudoin, D. Oceandy, S. Prehar, M. Zi, L. Neyses University of Manchester, Heart Failure Group, Manchester, United Kingdom Background: The plasma membrane calcium ATPase (PMCA) is a ubiq- uitously expressed calcium-extruding enzymatic pump which is the only system to extrude calcium from the cytosol of the majority of cells. In the heart, however, the sodium/calcium exchange is responsible for bulk calcium removal, leaving the role of PMCA unclear. We have previously generated a null mutant mouse line (PMCA4 KO) in order to elucidate the role of the ubiquitously expressed isoform 4 of PMCA in the healthy and failing heart. Results: Analysis of the heart by echocardiography revealed no differ- ences in heart rate, wall and septum thicknesses and fractional shortening between PMCA4 KO and wild type (WT) controls, and blood pressure re- mained unaltered. Invasive haemodynamic analysis did, however, reveal that both contractility and speed of relaxation were significantly elevated in PMCA4 KO mice. To determine the pathophysiological relevance of PMCA4 in the heart hypertrophy was induced by chronic beta-adrenergic stimulation. PMCA4 KO and WT mice showed the same hypertrophic response leading to increased cardiac mass and wall thickness, however, PMCA4 KO mice did not display the normal deleterious delay in diastolic relaxation. To determine if PMCA4 is a potential target for drug treatment of diastolic dysfunction associated with hypertrophy we employed systems biology by analysing over 100 parameters to determine the phenotypic effect of its deletion on the whole mouse. We determined that there was no deleterious effect due to the deletion of this calcium pump on skeletal formation, plasma chemistry parameters including calcium levels, calorimetry, auditory and visual functions, and behavioural characteristics. We have previously reported that male mice are infertile due to a defect in sperm motility. Conclusion: This analysis has shown that although PMCA4 is ubiqui- tously expressed its function is highly tissue specific, with physiolog- ical/pathophysiological relevance in the sperm and cardiovascular sys- tem. It identifies PMCA4 as a novel target for developing inhibitors for the treatment of diastolic dysfunction.