In the heart, the existence of an electrical memory was firstly reported by Rosenbaum et al. (1982), but Rios et al. (1975) and Garcia Moreira (1977) were those that firstly described the existence of contractile memories in the amphibian myocardium. These authors developed a mathematical model for representing such phenomenon. In the present study, we aimed to characterize two kinds of contractile memories occurring in the mammalian myocardium. One of them, depresses the tissue (the depressant memory, DM) and the other one acts by stimulating it (the excitatory memory, EM). The pivotal rationale guiding this work was: when the heart is challenged by changing the environment sources like nutrients, chemicals, temperature, etc., its behavior changes in order to optimize the energy expenditure associated with its contractility. This adaptation process allows to be reached a new state of dynamic equilibrium. In order to express such behavior, the tissue creates contractile memories for adjusting the amplitude of myocardial forces. This is provided by balancing the load of DM and EM available at each myocardial beat. The expression and accumulation of these memories were studied in the guinea pig atria submitted to the experimental protocols described previously by Seed & Walker (1988), Shimizu (2000), and Conde-Garcia (not published). The expression and accumulation of myocardial memories were described by employing two static descriptors, LODMmax and LOEMmax. They stand for the maximum load of depressant memory and the maximum load of excitatory memory, respectively. Furthermore, another pair of dynamic descriptors was also used to measure the maximum rate of erasing of the depressant memory (MREDM) and the other one to measure the maximum rate of erasing of the excitatory memory (MREEM). The static descriptors represent the transference of load of both memories but the dynamic descriptors were related to the rate of erasing of such memories. Our results brought us onto the following conclusions: 1. contractile memories are a phenomenon apart from the electrical memory because rising the external potassium from 2.7 to 7.0 mM did not modify (n n = 4) LODMmax that changed from 82,09 ± 1,58 to 81,56 ± 2,01% (p > 0,05), LOEMmax from 83,36 ± 0,56 to 90,12 ± 17,92% (p > 0,05), MREDM changed from -1,36 ± 0,67 to -1,13 ± 0,42gf/s (p > 0,05), and MREED from -2,09 ± 1,65 to -1,56 ± 1,41gf/s (p > 0,05). 2. However, the expression and accumulation of DM and EM are affected by the intracellular calcium transient. The increase of extracellular calcium from 1,37 to 5,47mM (n = 3) reduced LODMmax: from 87,56 ± 2,33 to 63,83 ± 3,78% (p < 0,05); LOEMmax from 84,36 ± 0,54 to 13,91 ± 0,11% (p < 0,05); MREDM from -2,58 ± 0,71 to -1,20 ± 0,37gf/s (p < 0,05) and MREEM from -0,90 ± 0,13 to -0,34 ± 0,05 gf/s (p < 0,05). Adding 5mM cafeine to the bath solution also reduced LODMmax from 79,88 ± 3,48 to 56,68 ± 6,62% (p < 0,05); LOEMmax from 77,14 ± 1,02 to 28,54 ± 2,11% (p < 0,05); MREDM from -1,78 ± 0,50 to -0,60 ± 0,10 gf/s (p < 0,05), and MREED from -1,74 ± 0,64 to -0,33 ± 0,14 gf/s (p < 0,05); 3. In the experimental condition employed in this work, a given beat receives both depressant and excitatory information built by the last ten beats. / A capacidade de o miocárdio memorizar foi estudada inicialmente por Rosenbaum (1982), que, entre outros, relataram uma memória elétrica no coração. Todavia, Rios e cols. (1975) e Moreira (1977) foram os primeiros a descrever a existência de memória contrátil no miocárdio de anfíbio. Eles propuseram um modelo matemático para representar esse fenômeno. A nossa proposta, contudo, visou caracterizar dois tipos de memórias contráteis. Uma delas inibe o inotropismo (memória depressora, MD) e a outra, o estimula (memória excitadora, ME). A hipótese central deste trabalho propõe que, quando o coração é desafiado por um novo ambiente (nutrientes, químicos, pH etc.), ele redefine sua atividade contrátil para que possa alcançar um novo estado de equilíbrio. Para expressar tal comportamento, o miocárdio cria memórias, visando ajustar a amplitude das forças geradas. Isto se dá por meio do balanço entre a carga de MD e de ME de cada batimento. Neste trabalho, a expressão e a acumulação destas memórias foram estudadas em átrio de cobaia, utilizando-se dois descritores para cada uma delas um estático, o IKMDmax e IKMEmax, que representam o incremento máximo de carga de MD e ME, respectivamente, e outro dinâmico VmedAMD e VmedAME - que está associado à velocidade de apagamento de cada memórias. As preparações foram ensaiadas com diferentes protocolos experimentais como os descritos por Seed & Walker (1988), Shimizu, et al. (2000) e Conde-Garcia (não publicado). Os resultados mostraram que a memória contrátil difere do fenômeno relativo à memória elétrica do miocárdio, porque, elevando-se o potássio externo de 2,7 para 7,0 mM, não houve variação significativa dos descritores, pois, para n = 3, o IKMDmax passou de 82,09 ± 1,58 para 81,56 ± 2,01% (p > 0,05), o IKMEmax passou de 83,36 ± 0,56 para 90,12 ± 17,92% (p > 0,05), a VmedAMD variou de -1,36 ± 0,67 para -1,13 ± 0,42gf/s (p > 0,05) e a VmedME foi alterada de -2,09 ± 1,65 para -1,56 ± 1,41gf/s (p > 0,05). A expressão e a acumulação das memórias são fenômenos que dependem do transiente intracelular de cálcio nas células miocárdicas. A elevação do cálcio extracelular de 1,37 para 5,47mM, para n = 3, alterou o IKMDmax: de 87,56 ± 2,33 para 63,83 ± 3,78% (p < 0,05); IKMEmax: 84,36 ± 0,54 para 13,91 ± 0,11% (p < 0,05); VmedAMD: -2,58 ± 0,71 para -1,20 ± 0,37gf/s (p < 0,05) e VmedME: -0,90 ± 0,13 para -0,34 ± 0,05 gf/s (p < 0,05). A adição de 5mM de cafeína à solução controle do banho fez o IKMDmax variar de 79,88 ± 3,48 para 56,68 ± 6,62% (p < 0,05); o IKMEmax de 77,14 ± 1,02 para 28,54 ± 2,11% (p < 0,05); a VmedAMD de -1,78 ± 0,50 para -0,60 ± 0,10 gf/s (p < 0,05) e a VmedME -1,74 ± 0,64 para -0,33 ± 0,14 gf/s (p < 0,05). Nas condições experimentais deste estudo, uma dada contração recebe informações depressoras e excitadoras que foram geradas pelos últimos dez batimentos.

Made available in DSpace on 2016-01-26T18:55:41Z (GMT). No. of bitstreams: 1 adriana junqueira.pdf: 634783 bytes, checksum: 52945121a1cc60fa69b359adf719311f (MD5) Previous issue date: 2014-09-29 / Objective-This study aimed to evaluate the effects of growth hormone (GH), in rats submitted to resistance training (RT) on cardiac remodeling in morphological aspects, Ca2+ genes and cardiac marker. Design- Wistar male rats were divided into 4 groups: control (CT, n = 7), Growth Hormone (GH, n = 7), Resistance Training (RT, n = 7) and Resistance Training with Growth Hormone administration (RTGH, n = 7). The GH dose was 0,2 IU/kg through subcutaneous administration every two days, and the RT model used was the vertical jump in water (4 sets of 10 jumps/day, 3 sessions/week) both for 30 consecutive days. Anatomical variables such as final body weight (FBW), left ventricle weight (LV) and the LV/FBW ratio of rats were evaluated. The morphology analysis consisted of the cardiomyocytes cross-sectional area (HE) and collagen fraction (picrosirius). The mRNA of the proteins of the calcium pump of the sarcoplasmic reticulum Ca2+ ATPase (SERCA2a), phospholamban (PLB) and ryanodine (RyR) infarction were evaluated by real-time PCR (qPCR). The cardiac marker dosed was creatine kinase muscle-brain fraction (CK-MB), through serum analysis Results- FBW, LV weight, LV/FBW ratio, cardiomyocytes cross-sectional area, as and SERCA2a, PLB and RyR gene expression, showed no statistical difference between the groups, whereas for the collagen assessment , an increase in RT group (p <0,05) was observed when compared to other groups (CT, GH and RTGH). In biochemical analysis of CK-MB there was statistical difference between trained groups and untrained groups. Conclusion- The RT interferes with cardiac remodeling by increasing interstitial collagen, which may result from the myocardial injury characterized by increased CK-MB, however, when combined with GH collagen remained unchanged. / Objetivo- Este estudo teve como objetivo avaliar os efeitos do Hormônio do Crescimento (GH), em ratos submetidos ao Treinamento Resistido (TR) sobre remodelação cardíaca nos aspectos morfológicos, genes do Ca2+ e marcador cardíaco. Desenho- Ratos Wistar machos foram distribuídos em 4 grupos: controle (CT, n=7), Hormônio do Crescimento (GH, n=7), Treinamento Resistido (TR, n=7) e Treinamento Resistido com Hormônio do Crescimento (TRGH, n=7). A dose do GH foi de 0,2 UI/Kg, via subcutânea, a cada dois dias e o modelo de TR utilizado foi o salto vertical na água (4 séries de 10 saltos/dia, 3 sessões/semana) ambos por 30 dias consecutivos. Foram avaliadas as variáveis anatômicas, peso corporal final (PCF), peso do Ventrículo Esquerdo (VE) e a relação VE/PCF. A análise morfológica constou da avaliação da área dos cardiomiócitos (Hematoxilina e Eosina-HE) e da fração de colágeno (Picrosirius-red). O nível de expressão do RNAm das proteínas da bomba de cálcio (Ca2+) do retículo sarcoplasmático Ca2+ ATPase (SERCA2a), fosfolambam (PLB) e rianodina (RyR) do miocárdio foi avaliado por PCR em tempo real (qPCR). A dosagem da creatina quinase fração músculo-cérebro (CK-MB), foi avaliada por meio de análise sérica. Resultados- O PCF, peso do VE, a relação VE/PCF, a área dos cardiomiócitos, e a expressão gênica SERCA2a, PLB e RyR, não mostrou diferença estatística entre os grupos. Para o colágeno, houve aumento do grupo TR (p < 0,05), quando contrastado com os demais grupos (CT, GH e TRGH). Na análise bioquímica da CK-MB houve diferença estatística dos grupos treinados em relação aos grupos não treinados. Conclusão- O TR interfere na remodelação cardíaca aumentando o colágeno intersticial, que pode ser decorrente da lesão miocárdica caracterizada pelo aumento da CK-MB, porém, quando associado ao GH o colágeno não se alterou.

Made available in DSpace on 2016-07-18T17:53:14Z (GMT). No. of bitstreams: 1 adriana junqueira.pdf: 634783 bytes, checksum: 52945121a1cc60fa69b359adf719311f (MD5) Previous issue date: 2014-09-29 / Objective-This study aimed to evaluate the effects of growth hormone (GH), in rats submitted to resistance training (RT) on cardiac remodeling in morphological aspects, Ca2+ genes and cardiac marker. Design- Wistar male rats were divided into 4 groups: control (CT, n = 7), Growth Hormone (GH, n = 7), Resistance Training (RT, n = 7) and Resistance Training with Growth Hormone administration (RTGH, n = 7). The GH dose was 0,2 IU/kg through subcutaneous administration every two days, and the RT model used was the vertical jump in water (4 sets of 10 jumps/day, 3 sessions/week) both for 30 consecutive days. Anatomical variables such as final body weight (FBW), left ventricle weight (LV) and the LV/FBW ratio of rats were evaluated. The morphology analysis consisted of the cardiomyocytes cross-sectional area (HE) and collagen fraction (picrosirius). The mRNA of the proteins of the calcium pump of the sarcoplasmic reticulum Ca2+ ATPase (SERCA2a), phospholamban (PLB) and ryanodine (RyR) infarction were evaluated by real-time PCR (qPCR). The cardiac marker dosed was creatine kinase muscle-brain fraction (CK-MB), through serum analysis Results- FBW, LV weight, LV/FBW ratio, cardiomyocytes cross-sectional area, as and SERCA2a, PLB and RyR gene expression, showed no statistical difference between the groups, whereas for the collagen assessment , an increase in RT group (p <0,05) was observed when compared to other groups (CT, GH and RTGH). In biochemical analysis of CK-MB there was statistical difference between trained groups and untrained groups. Conclusion- The RT interferes with cardiac remodeling by increasing interstitial collagen, which may result from the myocardial injury characterized by increased CK-MB, however, when combined with GH collagen remained unchanged. / Objetivo- Este estudo teve como objetivo avaliar os efeitos do Hormônio do Crescimento (GH), em ratos submetidos ao Treinamento Resistido (TR) sobre remodelação cardíaca nos aspectos morfológicos, genes do Ca2+ e marcador cardíaco. Desenho- Ratos Wistar machos foram distribuídos em 4 grupos: controle (CT, n=7), Hormônio do Crescimento (GH, n=7), Treinamento Resistido (TR, n=7) e Treinamento Resistido com Hormônio do Crescimento (TRGH, n=7). A dose do GH foi de 0,2 UI/Kg, via subcutânea, a cada dois dias e o modelo de TR utilizado foi o salto vertical na água (4 séries de 10 saltos/dia, 3 sessões/semana) ambos por 30 dias consecutivos. Foram avaliadas as variáveis anatômicas, peso corporal final (PCF), peso do Ventrículo Esquerdo (VE) e a relação VE/PCF. A análise morfológica constou da avaliação da área dos cardiomiócitos (Hematoxilina e Eosina-HE) e da fração de colágeno (Picrosirius-red). O nível de expressão do RNAm das proteínas da bomba de cálcio (Ca2+) do retículo sarcoplasmático Ca2+ ATPase (SERCA2a), fosfolambam (PLB) e rianodina (RyR) do miocárdio foi avaliado por PCR em tempo real (qPCR). A dosagem da creatina quinase fração músculo-cérebro (CK-MB), foi avaliada por meio de análise sérica. Resultados- O PCF, peso do VE, a relação VE/PCF, a área dos cardiomiócitos, e a expressão gênica SERCA2a, PLB e RyR, não mostrou diferença estatística entre os grupos. Para o colágeno, houve aumento do grupo TR (p < 0,05), quando contrastado com os demais grupos (CT, GH e TRGH). Na análise bioquímica da CK-MB houve diferença estatística dos grupos treinados em relação aos grupos não treinados. Conclusão- O TR interfere na remodelação cardíaca aumentando o colágeno intersticial, que pode ser decorrente da lesão miocárdica caracterizada pelo aumento da CK-MB, porém, quando associado ao GH o colágeno não se alterou.

A hipertrofia ventricular esquerda (HVE) é importante fator de risco cardiovascular. O objetivo deste estudo retrospectivo foi verificar a associação de critérios eletrocardiográficos de HVE com as características anatômicas e histológicas do coração, em 51 pacientes submetidos à necropsia. Procedeu-se à medição do diâmetro transverso dos cardiomiócitos e da porcentagem de fibrose do ventrículo esquerdo e direito. Entre os pacientes que apresentavam HVE anatômica, o critério de Romhilt foi positivo em 92,3%, sendo superior aos demais critérios avaliados, com especificidade de 89,5% e sensibilidade de 68,8%, Foi o único que se associou a características anatômicas e histológicas do coração / The left ventricular hypertrophy (LVH) is an important cardiovascular risk factor. The purpose of the present retrospective paper is to examine the association of LVH electrocardiographic criteria with both anatomical and histological characteristics of the heart on 51 patients submitted to the necropsy. The study carried out the measurement of the transverse diameter of cardiomyocytes, as well as the percentage of fibrosis at both left and right ventriculi. Among those patients who presented anatomic LVH, the Romhilt criterium resulted positive in 92.3% of the cases, thus surpassing the other criteria evaluated, with specificity and sensibility up to 89.5% and 68.8% respectively. This was the only criterium associated to both anatomic and histological characteristics of the heart

No description available.

Adaptation to chronic hypoxia provides myocardial protection against ischemia - reperfusion injury (IR). Cardioprotective effect of adaptation depends on the degree and duration of hypoxic exposure and daily regime of adaptation. Certain protective regimes of adaptations to hypoxia have been reported to activate proapoptotic signaling pathways and bioactive sphingolipids were recently shown to play important role in the regulation of apoptosis in the heart. We aimed to determine the mRNA level of selected genes related to apoptotic pathways and to sphingolipid metabolism in two models of hypoxic adaptation, continous normobaric hypoxia (CNH 10% O2) with different exposures (4h, 48h, 120h, 21days) and intermitent hypobaric hypoxia (IHH 7000 m, 8h/day). Both ventricles, LV and RV, were analysed after adaptation to CNH and only LV was analysed after IHH adaptation. Our results show that both types of adaptation increased mRNA of proapoptotic genes, CNH mainly in RV and IHH in LV. Furthermore, increased expressions of proapoptotic genes were accompanied by the increase of expression of enzymes producing predominantly protective kinds of sphingolipids. The exact role of apoptosis and sphingolipid signaling molecules in endogenous myocardial protection requires further research. Key words: Apoptosis,...

The objective of the current study is to present the case of an intercollegiate basketball player diagnosed with an ifliopathic cardiomyopathy. The athlete illustrated in the case study experienced ongoing chest discomfort with exercise. Episodic chest pain and syncope in athletes is often alarming and may signal an underlying cardiac condition. Early recognition and maJagement of these athletes is vital to the prevention of sudden cardiac death (SCD). Fortunately, the athlete was referred to a cardiologist by her team physician during her pre-participation physical examination to rule out heart conditions that may lead to SCD. The athlete was presented a mildly reduced ejection fraction during her screening with the cardiologist. In cardiovascular physiology, ejection fraction is the fraction of end-diastolic volume that is ejected from the ventricle with each heart beat. Damage to the myocardium, as seen in cardiomyopathies, decreases the heart's ability to eject blood and therefore reduces the ejection fraction. The athlete underwent VO2max testing as well where it was discovered that her VO2max was exceptionally low for a physically active division-I athlete. This low VO2max suggested that the athlete had an insufficient oxygen uptake during intense exercise. The athlete experienced a treatment protocol consisting of a progressive conditioning regimen of additional cardiovascular exercise that proved to be effective in raising her VO2max by 10%. The athlete returned to full participation and remained asymptomatic throughout the remainder of the season. The pre-participation physical examination is crucial in early detection of events that may lead to sudden cardiac death. A thorough history and physical examination are the most efficient screening methods for detecting cardiovascular abnormalities. Any athlete with episodes of syncope, hypertension, or changes in heart rhythm should be referred to a physician.

A substance that cross-reacts with antiserum to human atrial natriuretic peptide (ANP) is found in fish hearts. This ANP-like material increases sodium output from the gill and kidney while inhibiting sodium uptake in the gut. Mammalian ANP secretion is stimulated by glucocorticoids, and cortisol injection increases sodium output in salt-loaded fish. Therefore, we wanted to determine if the release of ANP in fish is sensitive to dexamethasone. Ventricle cardiocytes from the rainbow trout Oncorhynchus mykiss were treated with various doses of dexamethasone for 18 or 72 h. Single ventricle cells were then assayed for ANP release using a reverse hemolytic plaque assay and antiserum to human alpha-ANP. Incubation with 100 microM dexamethasone almost doubled the population of ventricle cells committed to ANP release (basal, 15.0 +/- 0.3% vs. Dexamethasone, 28.3 +/- 1.4%; values are percent plaque formation +/- SE). Stimulation of ANP secretion was dependent on dose and time of exposure to dexamethasone. These results suggest that ANP secretion in fish is regulated by glucocorticoids.

The immune system plays critical roles in the human heart in health, injury, and disease. Of the major immune cell types that reside in the cellular landscape of the myocardium, macrophages are particularly prevalent. Macrophages are responsible for a wide range of biological processes, including immunosurveillance, maintaining cardiomyocyte homeostasis, and regulating electrical conduction of cardiomyocytes. Within certain pathophysiological contexts such as Myocardial Infarction, they also facilitate the initiation and resolution of inflammation, and regulate cardiac repair and remodeling, significantly affecting injury trajectory and outcome. In addition to these already intricate interactions, both the immune system and the cardiovascular system are known to display sex-specific disparities, particularly under pathophysiological conditions, which may have important ramifications for patient health. The complex interplay within the human cardiac immune system has become increasingly evident, and therefore, understanding the interactions along the immune-cardiac axis and how they may vary among patient populations is of great interest to the clinical and research communities. An opportunity to study these interactions is presented by leveraging recent advances in induced pluripotent stem cell technology to engineer iPSC-derived models, which enable patient-specific studies of immune-cardiac interactions in a highly controllable environment. In this dissertation, we engineer patient-specific iPSC-derived models for studying immune-cardiac interactions. In Chapters 1 and 2, we introduce the importance of engineered models for studying the functions of the human heart, review the current state of the field, and identify key ways in which these models can be advanced. In Chapter 3, we create an iPSC-derived engineered cardiac tissue model with a resident macrophage population and investigate its impact on the function of the model under healthy conditions. In Chapter 4, we illustrate the capacity of iPSC-derived models to be patient-specific by showing how iPSC-derived macrophages demonstrate sex-specific dimorphism that emerges in response to an inflammatory stimulus. Finally, in Chapter 5, we present the optimization of an engineered model of myocardial ischemia reperfusion injury, which can be applied in future studies to study immune-cardiac interactions in the context of injury. Collectively, this dissertation provides a set of engineered tools that can be leveraged for improved understanding of the relationship between the heart and the immune system.

Das Ziel der vorliegenden Arbeit war es, Mechanismen zu identifizieren, die an der Induktion von Zellwachstum und/oder Zelltod von Kardiomyozyten beteiligt sind. Zunächst wurde ein Modell entwickelt, das es erlaubt, genregulatorische Elemente in vivo zu identifizieren. Es wurden die verschiedenen Variablen, die die Expression in vivo ins Myokard injizierter Reportergenplasmide regulieren, analysiert. Es stellte sich heraus, daß die Injektion von Reportergenkonstrukten ins Myokard des Hundes ein ausgezeichnetes Modell darstellt zur Analyse der Genregulation im Myokard großer Säugetierspezies. Mit Hilfe dieses Modells gelang durch Injektion von ANF (atrialer natriuretischer Faktor)-Promotorkonstrukten mit anschließendem aortic banding die Identifizierung einer AP1-Bindungsstelle im Promotor des ANF-Gens als cis-regulatorisches Element, das für die Aktivierung des ANF-Gens bei der Druckhypertrophie verantwortlich ist. Zur Identifizierung von Faktoren, die für den Zellzyklusarrest von Kardiomyozyten verantwortlich sind, wurde der ubiquitär exprimierte Transkriptionsfaktor E2F-1 in isolierte Kardiomyozyten mittels adenoviralem Gentransfer eingebracht. Die Überexpression von E2F-1 in Kardiomyozyten führte zur Induktion von programmiertem Zelltod (Apoptose). Die Apoptose wurde in Anwesenheit von Insulin-like Growth Factor-I (IGF-I) supprimiert und es konnte nun gesteigerte DNA-Synthese beobachtet werden. Es zeigte sich weiterhin, daß die Zellzyklusinhibitoren p21CIP1 und p27KIP1 eine besondere Rolle bei der Aufrechterhaltung des Zellzyklusarrestes von Kardiomyozyten spielen, denn in der Anwesenheit von IGF-I verschwanden in Kardiomyozyten, die E2F-1 exprimierten, diese Faktoren aus den Komplexen, die sie mit Zyklinen und zyklin-abhängigen Kinasen (cdks) bilden. Um zu verstehen, über welche Faktoren Apoptose in Kardiomyozyten induziert und über welche intrazellulären Signalwege sie vermittelt wird, wurden isolierte Kardiomyozyten mit freien Sauerstoffradikalen (ROS) exponiert, von denen bekannt ist, daß sie in bestimmten Zellen in einem bestimmten Dosisbereich Apoptose erzeugen können. Obwohl beides, H2O2 und O2-, zur Induktion von Apoptose in Kardiomyozyten führt, werden jeweils unterschiedliche intrazelluläre Signalwege aktiviert. So führt H2O2 zur Freisetzung von mitochondrialem Cytochrom C, was mit einer Translokation von Bax an die Mitochondrien und seiner Interaktion mit dem anti-apoptotischen Faktor Bcl-2 einhergeht. Dies führt zur Aktivierung der Caspase 3. O2- hingegen führt zur Aktivierung der Caspase 6 und Spaltung von Lamin A. / The aim of the study was to elucidate mechanisms controlling death and growth of cardiomyocytes. First, a model was developed suitable to identify regulatory gene sequences in vivo. Multiple variables controlling expression of reportergene constructs injected into the heart were investigated. The results showed that injection of reportergene constructs into the heart of dogs is an appropriate model to analyse regulation of gene expression in vivo in large mammals. Using this approach reportergene constructs harboring the promoter of the ANF (atrial natriuretic factor)-gene were injected in dog hearts which were subjected to pressure overload by aortic banding. Serial mutations of the promoter region revealed an AP-1 like sequence to be of importance for the induction of this gene in pressure overload hypertrophy. In order to identify factors responsible for the cell cycle arrest of cardiomyocytes the transcription factor E2F-1 was overexpressed in isolated cardiomyocytes using adenoviral gene transfer. In cardiomyoccytes the overexpression of E2F1- was followed by apoptosis. Apoptosis was suppressed in the presence of insulin-like growth factor-I (IGF-I) and the re-induction of DNA synthesis could be observed. Cyclin dependent inhibitors (cdi) p21CIP1 and p27KIP1 appear to play an important role in the maintenance of the cell cycle arrest in cardiomyocytes, since these factors dissappeared from cyclin complexes in the presence of IGF-I. In order to understand how apoptosis is induced in cardiomyocytes and which intracellular signalling cascades may be involved, isolated cardiomyocytes were exposed to reactive oxygen species (superoxide anion (O2-) or hydrogen peroxide (H2O2)). Both O2- and H2O2 induced apoptosis in cardiomyocytes dose-dependently. However, different intracellular signalling cascades were activated. Cytochrome C was released by H2O2, but not by O2-. Release of cytochrome c was followed by translocation of Bax from the cytosol to mitochondria where it was interacting with anti-apoptotic Bcl-2 leading to the subsequent activation of caspase-3. O2- lead to an activation of caspase-6 which was followed by the cleavage of lamin A.