ABSTRACT
Introducción: el poscondicionamiento isquémico (PCI) es una estrategia protectora contra la injuria por reperfusión con propiedades antiarrítmicas. La hipertrofia cardíaca secundaria a la hipertensión arterial aumenta el riesgo de sufrir arritmias y, además, reduce la respuesta a algunos tratamientos. Objetivo: determinar si el efecto antiarrítmico del PCI se mantiene en corazones hipertróficos. Método: los corazones aislados de ratas Wistar Kyoto (WKY) y de ratas espontáneamente hipertensas (SHR) de la misma edad, fueron perfundidos según la técnica de Langendorff y sometidos a 15 min de isquemia regional. Al momento de la reperfusión se dividieron en: a) WKY, b) WKY-PCI, c) SHR, d) SHR-PCI (n=13 por grupo). El PCI consistió en tres ciclos de 30 s de reperfusión y 30 s de isquemia, al inicio de la reperfusión. Se clasificaron las arritmias ventriculares observadas en el ECG. Se estimó la hipertrofia por el peso cardíaco relativo. Resultados: la hipertensión arterial en las ratas SHR provocó hipertrofia miocárdica. Todos los corazones sufrieron una alta incidencia de fibrilación ventricular al inicio de la reperfusión (SHR 92,3% y WKY 77%, ns). El PCI restituyó el ritmo sinusal en los corazones de las ratas normotensas (WKY-PCI 61,5% vs WKY 23,1%, p=0,0236 por test de ji2) y en los de las SHR (SHR-PCI 69,2% vs SHR 15,4%, p=0,0016 test de ji2). Conclusión: el PCI fue capaz de restituir el ritmo sinusal en la mayoría de los corazones que presentaron arritmias ventriculares de reperfusión y el efecto antiarrítmico se mantuvo en corazones hipertróficos provenientes de ratas SHR.
Introduction: ischemic postconditioning (IPC) is a protective strategy against reperfusion injury with antiarrhythmic properties. Cardiac hypertrophy secondary to hypertension increases the risk of arrhythmias and also reduces the response to some treatments. Objective: to determine whether the antiarrhythmic effect of IPC was maintained in hypertrophic hearts. Methods: isolated rat hearts from Wistar Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) of the same age, were perfused according to Langendorff technique and subjected to 15 min regional ischemia. At the moment of reperfusion, hearts were divided into: a) WKY, b) WKY-IPC, c) SHR, d) SHR-IPC (each group, n= 13). The IPC consisted of 3 cycles of 30 s of reperfusion and 30 s of ischemia at the onset of reperfusion. Ventricular arrhythmias were diagnosed using ECG records. Hypertrophy was estimated by relative heart weight. Results: hypertension in SHR induce myocardial hypertrophy. All hearts underwent a high incidence of ventricular fibrillation (SHR 92,3% and WKY 77%, ns). IPC restored sinus rhythm in the hearts of normotensive rats (WKY-PCI 61,5% versus WKY 23,1%, p = 0,0236 by chi2 test) and in those from SHR (SHR-PCI 69% versus SHR 15,4%, p = 0,0016 chi2 test). Conclusion: IPC is able to restore sinus rhythm from most of the hearts that developed reperfusion ventricular arrhythmias and the antiarrhythmic effect remains in hypertrophic hearts from SHR rats.
ABSTRACT
A hipertensão arterial representa um fator de risco sistêmico e condição desfavorável para tratamentos dentários, especialmente aqueles que necessitam de reparação óssea. O objetivo deste estudo foi avaliar o reparo alveolar em ratos espontaneamente hipertensos (SHR) e o efeito do atenolol sobre este processo. Wistar e SHR tratados ou não com 100mg/kg/dia (atenolol), foram submetidos à extração do dente incisivo superior direito e sacrificados aos 7, 14, 21, 28 e 42 dias após a cirurgia. As hemi-maxilas foram removidas e as imagens radiográficas foram realizadas. A análise radiográfica foi obtida por meio do sistema digital Digora. Análises histológicas, histomorfométricas e reações imunoistoquímicas foram feitas em cortes histológicos de 5μm de espessura, os quais foram corados com hematoxilina-eosina ou submetidos à imunomarcação para RANK, RANKL, OPG e proteínas MMP-9. A análise histológica foi realizada por microscopia óptica e a análise histomorfométrica pelo software RGB / Leica Qwin Color. Os resultados densitométricos e histomorfométricos foram analisados pela Anova two-way. Na análise imunoistoquímica, utilizando um microscópio óptico, foram atribuídos scores às imagens. Os resultados foram analisados pelos testes estatísticos Kruskal-Wallis e Mann Whitney. As diferenças entre os resultados foram consideradas significativas quando p<0,05. Redução da densidade mineral óssea (DMO), menor porcentagem de osso e menor espessura do trabeculado ósseo foram observadas nos períodos finais do reparo alveolar em SHR. Aumento da imunomarcação para RANKL, RANK e MMP-9 foi observado em 28 dias após a cirurgia no alvéolo em SHR. Consistente efeito do atenolol foi observado no reparo alveolar de ratos hipertensos. O atenolol aumentou a DMO observada na maioria dos períodos analisados e aumentou a espessura do trabeculado ósseo nos 28º e 42º dias em alvéolos de SHR. Aumento na marcação para OPG aos 7º e 42º dias do reparo foram observados em SHR tratados. Aumento na...
Hypertension represents a systemic risk factor and unfavorable condition for dental treatments, especially treatments that require bone healing. The purpose of this study was to evaluate the alveolar wound healing in spontaneously hypertensive rats (SHR) and the atenolol effect on this process. Normotensive Wistar rats and SHR, untreated or treated with atenolol (100mg/kg/day), were submitted to the extraction of the upper right incisive tooth and sacrificed at 7, 14, 21, 28 and 42 days after surgery. The hemi-jaws were extracted and the radiographic images were obtained. Radiographic analysis was performed by using the digital system Digora. Histological, histomorphometric and immunohistochemical reactions were done in histological sections, 5 μm thick, stained with hematoxylin and eosin or subjected to immunolabeling to RANK, RANKL, OPG and MMP-9 proteins. Histological analysis was performed by light microscopy and histomorphometric analysis by Leica Qwin Color/RGB software. The densitometric and histomorphometric results were also analyzed by two-way ANOVA. In immunohistochemical analysis, using an optical microscopy, scores were assigned to the images. Results were analyzed by KruskalWallis and Mann Whitney statistical tests. Differences between results were considered significant when p <0.05. Reduced bone mineral density (BMD), lower bone percentage and less thickness of trabecular bone was observed in the final periods of alveolar bone healing in SHR. Increased RANKL, RANK and MMP-9 immunolabeling were observed at 28 days after surgery in SHR alveolus. Consistent atenolol effect was observed on alveolar bone healing of hypertensive rats. Atenolol increased the BMD observed in most of the periods analyzed and increased trabecular bone thickness at 28 and 42 days in SHR alveolus. Increased OPG immunolabeling at 7 and 42 days of alveolar healing were observed in treated SHR. Increased expression of RANKL and MMP-9 at 21 and 42 days, and increased RANK