Several studies have demonstrated the feasibility of gene cardium. Transgene expression is predominant in the left transfer into the heart muscle. However, all the available ventricle and the interventricular septum but limited in the data also indicate that the extent of transfection remains right ventricle. In vivo echocardiographic measurements of limited. As an alternative method to intravascular administhe left ventricular diameters at end diastolic and end systration, we have developed a novel strategy which uses tolic times show no difference between virus-and shamthe pericardial sac. When a replication-deficient adenovirus injected animals, thus indicating a good clinical tolerance containing the cDNA encoding a bacterial ␤-galactosidase to this strategy of virus delivery. The same protocol has is injected into the pericardial sac of adult Wistar rats the been used with the same efficiency in mice, which leads staining is exclusively restricted to the pericardial cell layus to propose injection into the pericardial sac as an effecers. However, injecting a mixture of collagenase and hyalutive and harmless method for gene transfer into the heart ronidase together with the virus, leads to a large diffusion muscle. of the transgene activity, reaching up to 40% of the myo-

Muscular dystrophies are often associated with significant cardiac disease that can be the prominent feature associated with gene mutations in sarcoglycan. Cardiac cell death is a main feature of cardiomyopathy in sarcoglycan deficiency and may arise as a cardiomyocyte intrinsic process that remains unclear. Deficiency of delta-sarcoglycan (delta-SG) induces disruption of the dystrophin-associated glycoprotein complex, a known cause of membrane instability that may explain cardiomyocytes cytosolic Ca2+ increase. In this study we assessed the hypothesis that cytosolic Ca2+ increase triggers cardiomyocyte death through mitochondrial Ca2+ overload and dysfunction in the delta-SG-deficient CHF147 hamster. We showed that virtually all isolated CHF147 ventricular myocytes exhibited elevated cytosolic and mitochondrial Ca2+ levels by the use of the Fura-2 and Rhod-2 fluorescent probes. Observation of living cells with Mito-Tracker red lead to the conclusion that approximately 15% of isolated CHF147 cardiomyocytes had disorganized mitochondria. Transmission electron microscope imaging showed mitochondrial swelling associated with crest and membrane disruption. Analysis of the mitochondrial permeability transition pore (MPTP) activity using calcein revealed that mitochondria of CHF147 ventricular cells were twofold leakier than wild types, whereas reactive oxygen species production was unchanged. Bax, Bcl-2, and LC3 expression analysis by Western blot indicated that the intrinsic apoptosis and the cell death associated to autophagy pathways were not significantly activated in CHF147 hearts. Our results lead to conclusion that cardiomyocytes death in delta-SG-deficient animals is an intrinsic phenomenon, likely related to Ca2+-induced necrosis. In this process Ca2+ overload-induced MPTP activation and mitochondrial disorganization may have an important role.

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In vivo electrophysiology remains a suitable method to monitor cardiac activity; however, surface electrocardiogram (ECG) monitoring remains complicated in the case of small animals. Sedation has helped to maintain the animal still; however, it is known that anesthetic drugs impair the regulation of the cardiac electrical activity. To circumvent this problem, ECG monitoring using telemetry or restraints has been developed. This study reports a new methodology, based on a restraining system without further sedation, for recording ECGs on small animal models. We investigated its efficacy in Syrian hamsters and in several strains of mice, and we compared these data to those obtained with telemetry devices. We show that this new system can easily be used in animals of different sizes ranging from adult hamsters to newborn mice. When compared to telemetry, this restrained ECG monitoring method shows a very good yield, as 65% of total beats can be used for further analysis. When recorded in the same animals, RR intervals distributions are identical for both techniques. In conclusion, this restrained ECG monitoring technique is a well-suited tool for exploring various aspects of cardiac electrophysiology in a wide variety of small animals including very young mice.

Dilated cardiomyopathies (DCM) are due to progressive dilatation of the cardiac cavities and thinning of the ventricular walls and lead unavoidably to heart failure. They represent a major cause for heart transplantation and, therefore, defining an efficient symptomatic treatment for DCM remains a challenge. We have taken advantage of the hamster strain CHF147 that displays progressive cardiomyopathy leading to heart failure to test whether stimulation of a hypertrophic pathway could delay the process of dilatation.Six month old CHF147 hamsters were treated with IGF-1 so that we could compare the efficacy of systemic administration of human recombinant IGF-1 protein (rh IGF-1) at low dose to that of direct myocardial injections of a plasmid DNA containing IGF-1 cDNA (pCMV-IGF1).IGF-1 treatment did not induce a significant variation of ventricle mass, but preserved left ventricular (LV) wall thickness and delayed dilatation of cardiac cavities when compared to non-treated hamsters. Together with this reduction of dilatation, we also noted a reduction in the amount of interstitial collagen. Furthermore, IGF-1 treatment induced beneficial effects on cardiac function since treated hamsters presented improved cardiac output and stroke volume, decreased end diastolic pressure when compared to nontreated hamsters and also showed a trend towards increased contractility (dP/dt(max)).This study provides evidence that IGF-1 treatment induces beneficial structural and functional effects on DCM of CHF147 hamsters, hence making this molecule a promising candidate for future gene therapy of heart failure due to DCM.

Several hamster strains are commonly used as models for cardiomyopathic phenotypes evolving toward heart failure. However, little is known about heart rate variability (HRV) in this species. Prolonged surface ECG recording, a prerequisite to HRV studies, can be obtained either by telemetry or by restraints. Here, we performed long time ECG recording using telemetry on young adult Syrian hamsters and we analyzed time series of interbeat intervals. Standard statistics showed that the mean of normal R-R intervals slightly increased with age, with standard deviation of normal R-R intervals remaining stable over time. However, time domain analysis using Poincaré plots revealed dynamic changes in the HRV. Analysis of frequency domains revealed that the ratio of spectral components (low frequency/high frequency) exhibited a maturation pattern. Thus refined analysis of HRV revealed a more complex pattern than common statistical analysis would translate. Unlike other rodents, hamsters display a great spontaneous variability of their heart rate. As the complexity canvas of HRV might be the consequence of extracardiac regulation factors, we assessed the sympathovagal balance in both time and frequency domain of heart rate. Pharmacological tests revealed that both sympathetic and vagal tones contribute to HRV in Syrian hamsters. Thus Syrian hamsters have a broad intrinsic HRV with large influences of the neurovegetative system. However, the influence of the previous beat seems to prevail over the autonomic oscillators. These animals present a high sensitivity to artificially altered cardiac regulation and might be great models for the diagnosis of early alterations in the HRV related to pathology. Therefore, Syrian hamsters represent a unique model for HRV studies.

This study is the first one reporting beneficial effects of IGF-1 treatment on survival of an animal model presenting DCM. Our results raise hopes for a new therapeutic approach of this pathology.

Several methods allow monitoring electrocardiogram (ECG) in small animals. Sedation may help to maintain animals; however anaesthetic drugs impair the heart rate variability (HRV). Implantable telemetry devices allow experiments in freely moving animals; but this technique requires surgery and thus a prolonged recovering period is necessary prior to ECG recording. Contention is an alternative to these methods, provided a better understanding of its influence on HRV. This study aimed at investigating the impact of contention on some HRV parameters.Telemetric and restrained ECG of Syrian hamsters were performed with TA10ETA‐F20 sensors and the EasyCG system, respectively. Time domain analysis based either on statistical or autoregressive approaches showed no significant difference in HRV at baseline. Investigations in the frequency domain revealed that restrains influenced low frequencies, translating a higher sympathetic activity. Pharmacological assays confirmed that restraints affected the sympathovagal balance.In conclusion, the imprint of contention on HRV was consistent with a shift of the sympathovagal balance towards a higher sympathetic tone.Funding: Association Française contre les Myopathies