Desencadeamento de arritmias e morte súbita por pequeno grau de estress em camundongos com distrofia tipo cinturas
USA – camundongos com distrofia muscular tipo cinturas, deficientes em delta sarcoglican, quando submetidos a pequeno estress apresentam arritmias cardíacas e morte súbita. Controle do estress e da desregulação do sistema nervoso autônomo pode garantir melhor qualidade de vida.
O resumo em inglês pode ser lido abaixo:
(Experimental Biology, 2014) Acute mild stress induces cardiac arrhythmias and sudden death in sarcoglycan delta deficient mice, a model of muscular dystrophy
Rasna Sabharwal and Mark Chapleau
Muscular dystrophy is a catastrophic neuromuscular disease characterized by muscle wasting and weakness and dilated cardiomyopathy (DCM). We recently demonstrated that sarcoglycan delta deficient (Sgcd-/-) mice, an established model of muscular dystrophy, exhibit sympathovagal imbalance at a young age prior to development of DCM and premature death[Clin Auton Res 20(5):300, 2010]. We hypothesized that the combination of autonomic dysregulation and DCM in middle-aged Sgcd-/- mice confers susceptibility to acute stress-induced cardiac arrhythmias and sudden death. Blood pressure (BP), heart rate (HR), electrocardiogram and HR variability (HRV, SD of R-R interval) were measured by telemetry in control C57BL/6 and Sgcd-/- mice (50-60 wks of age). Acute mild psychosocial stress was induced by two methods: brief (<1min) hand-held restraint and ~15 minute exposure to an intruder mouse. In control mice, both types of stress transiently increased HR without affecting mean BP or HRV. In contrast, Sgcd-/- mice immediately assumed a supine position after hand-held restraint for several seconds accompanied with marked increase in HR (760±20 vs. 616±20 bpm at baseline, P<0.05) and arrhythmias. Exposure of Sgcd-/- mice to an intruder mouse initially increased HR mice, decreased HRV, and triggered arrhythmias (see Table). These responses were not associated with a postural change and were followed by progressive bradyarrhythmias, hypotension, ventricular fibrillation and death in 40% of Sgcd-/- mice. We conclude: 1) Acute mild stress induces cardiac arrhythmias and sudden death in Sgcd-/- mice; and 2) Therapeutic targeting of both autonomic dysregulation and stress disorders may yield better clinical outcomes in muscular dystrophy.
