Accelerated cardiomyopathy in mice with overexpression of cardiac G(s)alpha and a missense mutation in the alpha-myosin heavy chain

Article

关键词: FAMILIAL HYPERTROPHIC CARDIOMYOPATHY;    TRANSGENIC MICE;    MOUSE MODEL;    MYOCYTES;    PATHOGENESIS;   

DOI  :  10.1161/hc0502.103012

来源: SCIE

【 摘 要 】

Background-To understand further the pathogenesis of familial hypertrophic cardiomyopathy, we determined how the cardiomyopathy induced by an Arg403-->Gln missense mutation in the alpha-myosin heavy chain (403) is affected by chronically enhancing sympathetic drive by mating the mice with those overexpressing G(s)alpha (G(s)alphax403). Methods and Results-Heart rate in 3-month-old conscious mice was elevated similarly (P<0.05) in mice overexpressing G(s)α (G(s)α mice; 746+/-14 bpm) and G(s)αx403 mice (718+/-19 bpm) compared with littermate wild-type mice (WT; 623+/-18 bpm) and 403 mice (594+/-16 bpm). Left ventricular ejection fraction (LVEF), as determined by echocardiography, was enhanced in G(s)αx403 mice (88+/-1%, P<0.001) compared with WT (69+/-1%), 403 (75+/-1%), and G(s)alpha (69+/-2%) mice. Isolated cardiomyocytes from G(s)alphax403 mice also exhibited higher (P<0.001) baseline percent contraction (11.9+/-0.5%) than WT (7.0+/-0.5%), 403 (5.5+/-0.5%), and G(s)α (7.8+/-0.3%) cardiomyocytes. Relaxation of myocytes was impaired in 403 mice compared with WT but enhanced in G(s)α and normalized in G(s)αx.403 mice. This was also observed in vivo. In vivo isoproterenol (0.1 μg . kg(-1) . min(-1)) increased LVEF to maximal levels in G(s)αx403 and G(s)α, whereas in 403, the response was attenuated compared with WT. At 10 months of age, G(s)αx403 had significantly depressed LVEF (57+/-4%). Histopathological examination demonstrated at myocyte hypertrophy and fibrosis were already present in young G(s)αx403 mice and that old animals had severe cardiomyopathy. By 15 months of age, the survival of G(s)αx403 was 0% compared with 100% for WT, 71% for G(s)α, and 100% for 403 mice (P<0.05). Conclusions-These results show that the cardiomyopathy developed by G(s)alphax403 mice is synergistic rather than additive, most likely owing to the elevated baseline function combined with enhanced responsiveness to sympathetic stimulation.

【 授权许可】

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