Miocardiopatía arritmogénica. Genes y proteínas desmosómicas / Arrhythmogenic Cardiomyopathy. Genes and Desmosomal Proteins

RESUMEN Desde 1996 esta enfermedad figura en la clasificación de las miocardiopatías de la OMS con el nombre de "miocardiopatía arritmogénica". A fines de la década del 70 se estableció que el ventrículo derecho (VD) puede ser el sustrato para el desarrollo de arritmias. En la década del 80 se describió el reemplazo del miocardio por tejido fibroadiposo y su naturaleza hereditaria. Posteriores descubrimientos permitieron la identificación de varios genes implicados en la producción de proteínas desmosómicas que participan en el acoplamiento intercelular lo cual llevó a definir a la miocardiopatía arritmogénica como una enfermedad desmosómica. El electrocardiograma y el ecocardiograma resultaron fundamentales y la angiocardiografía invasiva se utilizó para detectar disquinesia-aquinesia y aneurismas del VD. La biopsia endomiocárdica se perfiló como el gold standard para el diagnóstico, debido a su capacidad para detectar el reemplazo transmural por tejido fibroadiposo. El advenimiento de la resonancia magnética cardíaca (RMC) con realce tardío de gadolinio ha permitido revelar no solamente anomalías morfológico-funcionales sino también daño tisular. El conocimiento de la estructura del disco intercalar, involucrado en el acoplamiento intercelular ha permitido determinar que no solamente los desmosomas estarían comprometidos, sino que habría varias proteínas constituyentes tanto de los desmosomas, como de las uniones adherentes, las uniones gap, y los canales iónicos, integradas en una unidad conocida como "área composita". Ésta constituye una amalgama entre elementos de sostén y canales iónicos que participan en la propagación del potencial de acción, lo que ha permitido desarrollar el concepto de disco intercalar compuesto por los llamados "nodos excitoadhesivos". Las implicancias clínicas en el desarrollo de arritmias malignas son obvias.

ABSTRACT In 1996 this disease was introduced into the WHO classification of cardiomyopathies with the term "arrhythmogenic cardiomyopathy". By the end of the 70s the right ventricle (RV) was identified as a substrate for the development of arrhythmias. The replacement of the myocardium by fibrofatty tissue and the hereditary nature of this condition were described in the 1980s. Later findings led to the identification of several genes involved in the production of desmosomal proteins participating in intercellular coupling, which led to defining arrhythmogenic cardiomyopathy as a desmosomal disease. Electrocardiography and echocardiography are fundamental tools, and invasive angiocardiography was used to detect dyskinesia-akinesia and right ventricular aneurysms. Endomyocardial biopsy was established as the gold standard for the diagnosis due to its ability to detect transmural replacement by fibrofatty tissue. The advent of cardiac magnetic resonance imaging (CMRI) with late gadolinium enhancement reveals morphological and functional abnormalities and tissue damage. The understanding of intercalated disc structure involved in intercellular coupling has made it possible to determine that, apart from desmosomes, several desmosomal proteins, as adherens junctions, gap junctions and ion channels are integrated into a unit known as the " area composita". The area composita constitutes an amalgam between supporting elements and ion channels that participate in action potential propagation, which has led to develop the concept that intercalated discs are constituted by "adhesion/ excitability nodes". The clinical implications in the development of malignant arrhythmias are obvious.

Bretschneider Solution and Two Antianginal Drugs Protect Peripheral Tissue in an Animal Model of Hemorrhagic Shock.

ABSTRACT: Shock and subsequent resuscitation provoke ischemia-reperfusion injury. Trimetazidine (TMZ), allopurinol (ALO), and histidine-tryptophan-ketoglutarate (HTK) solution, can protect from ischemia-reperfusion injury in chronic coronary syndromes and in transplantation. The objective of the current study is to compare, in a hemorrhagic shock and standard resuscitation animal model, organ damage parameters between placebo and treatment with TMZ, ALO, or HTK. Shock was induced in Wistar rats by controlled arterial bleeding, maintaining mean arterial pressure between 38 and 42 mm Hg for 60 minutes; then, drawn blood was reinfused. Animals were divided into: Sham (n = 4), Control (n = 6), TMZ (n = 7), ALO (n = 9), and HTK (n = 7). At the end of the experiment, animals were sacrificed and tissue harvested. TMZ, ALO and HTK decreased histopathologic damage in heart [Control: 1.72 (1.7-1.77); TMZ: 1.75 (1.72-1.79); ALO: 1.75 (1.74-1.8); HTK: 1.82 (1.78-1.85); all P < 0.05], kidney [Control: 3 (2-3); TMZ: 1 (1-2); ALO: 1 (1-1); HTK: 1(1-1); all P < 0.05] and intestine [Control: 3 (2-3); TMZ: 1 (1-2); ALO: 1 (1-1); HTK: 1 (0-2); all P < 0.05]. Also, treatment with TMZ, ALO, and HTK increased immunohistochemical expression of thioredoxin-1 in heart [Control: 6.6 (5.6-7.4); TMZ: 9.5 (8.1-9.7); ALO: 9.1 (8.4-10.2); HTK: 14.2 (12.6-15); all P < 0.05]; and kidney [Control: 4.6 (4-5.1); TMZ: 9.7 (9.3-9.9); ALO: 9.6 (9-9.9); HTK: 16.7 (16.1-17); all P < 0.05]. In an experimental model of hemorrhagic shock, TMZ, ALO, and HTK solution attenuated cell damage in multiple parenchyma and increased antioxidant defenses.

Structural changes in endocrine pancreas of male Wistar rats due to chronic cola drink consumption. Role of PDX-1.

AIM: The objective of this work was to analyze the structural changes of the pancreatic islets in rats, after 6 month consuming regular and light cola for 6 months. Also, we have analyzed the possible role of PDX-1 in that process. Finally, with the available knowledge, we propose a general working hypothesis that explains the succession of phenomena observed. Previously, we reported evidence showing that chronic cola consumption in rats impairs pancreatic metabolism of insulin and glucagon and produces some alterations typically observed in the metabolic syndrome, with an increase in oxidative stress. Of note It is worth mentioning that no apoptosis nor proliferation of islet cells could be demonstrated. In the present study, 36 male Wistar rats were divided into three groups to and given free access to freely drink regular cola (C), light cola (L), or water (W, control). We assessed the impact of the three different beverages in on glucose tolerance, lipid levels, creatinine levels and immunohistochemical changes addressed for the expression of insulin, glucagon, PDX-1 and NGN3 in islet cells, to evaluate the possible participation of PDX-1 in the changes observed in α and ß cells after 6 months of treatment. Moreover, we assessed by stereological methods, the mean volume of islets (Vi) and three important variables: the fractional ß -cell area, the cross-sectional area of alpha (A α-cell) and beta cells (A ß-cell), and the number of ß and α cell per body weight. Data were analyzed by two-way ANOVA followed by Bonferroni's multiple t-test or by Kruskal-Wallis test, then followed by Dunn's test (depending on distribution). Statistical significance was set at p<0.05. Cola drinking caused impaired glucose tolerance as well as fasting hyperglycemia (mean:148; CI:137-153; p<0.05 vs W) and an increase of in insulin immunolabeling (27.3±19.7; p<0.05 vs W and L). Immunohistochemical expression for PDX-1 was significantly high in C group compared to W (0.79±0.71; p<0.05). In this case, we observed cytoplasmatic and nuclear localization. Likewise, a mild but significant decrease of in Vi was detected after 6 months in C compared to W group (8.2±2.5; p<0.05). Also, we observed a significant decrease of in the fractional ß cell area (78.2±30.9; p<0.05) compared to W. Accordingly, a reduced mean value of islet α and ß cell number per body weight (0.05±0.02 and 0.08±0.04 respectively; both p<0.05) compared to W was detected. Interestingly, consumption of light cola increased the Vi (10.7±3.6; p<0.05) compared to W. In line with this, a decreased cross-sectional area of ß-cells was observed after chronic consumption of both, regular (78.2±30.9; p<0.05) and light cola (110.5±24.3; p<0.05), compared to W. As for, NGN3, it was negative in all three groups. Our results support the idea that PDX-1 plays a key role in the dynamics of the pancreatic islets after chronic consumption of sweetened beverages. In this experimental model, the loss of islets cells might be attributed to autophagy, favored by the local metabolic conditions and oxidative stress.