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J Hypertens ; 33(11): 2310-21, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26259125

RESUMO

OBJECTIVE: Left-ventricular hypertrophy and interstitial fibrosis are the main pathophysiological factors of heart failure with preserved ejection fraction. Blockade of the serotonin 5-HT2B receptor (5-HT2BR) has been shown to reduce cardiac hypertrophy, oxidative stress, and extracellular cell matrix activation. In this study, we evaluated the effects of the 5-HT2BR blockade, on hemodynamic and cardiac remodeling, in spontaneously hypertensive rats (SHRs) that display a diastolic dysfunction with preserved ejection fraction. METHOD: Thirty-seven-week-old SHRs were randomized in four groups receiving either saline, the selective 5-HT2BR antagonist RS-127445 (1 mg/kg per day), a calcium channel blocker nicardipine (6 mg/kg per day), or RS-127445 + nicardipine. During the 14 weeks of treatment period, cardiac function and blood pressure were monitored by echocardiography and tail-cuff. Finally, electrocardiograms and invasive hemodynamics were obtained before blood collection. Heart was analyzed for morphology and mRNA expression. A complementary study evaluated the cardiac and vascular effects of serotonin on wild-type and mice knockout for the 5-HT2BR (Htr2B) and/or the 5-HT2AR (Htr2A). RESULTS: Despite the left ventricular 5-HT2BR overexpression, 5-HT2BR blockade by RS-127445 did not affect left ventricular hypertrophy and fibrosis in SHRs. This antagonist did not improve diastolic dysfunction, neither alone nor in combination with nicardipine, although it induced plasma brain natriuretic peptide decrease. Moreover, RS-127445 amplified subendocardial fibrosis and favored left ventricular dilatation. Finally, a subendocardial left ventricular fibrosis was induced by chronic serotonin in wild-type mice, which was increased in Htr2B animals, but prevented in Htr2A and Htr2A/2B mice, and could be explained by a contribution of the endothelial 5-HT2BRs to coronary vasodilatation. CONCLUSION: This work is the first to identify a cardioprotective function of the 5-HT2BR in an integrated model of diastolic dysfunction with preserved ejection fraction.


Assuntos
Pressão Sanguínea/efeitos dos fármacos , Hipertensão/metabolismo , Hipertrofia Ventricular Esquerda/metabolismo , Antagonistas da Serotonina/farmacologia , Serotonina/metabolismo , Disfunção Ventricular Esquerda/metabolismo , Animais , Pressão Sanguínea/fisiologia , Ecocardiografia , Insuficiência Cardíaca/metabolismo , Insuficiência Cardíaca/fisiopatologia , Ventrículos do Coração/efeitos dos fármacos , Ventrículos do Coração/metabolismo , Ventrículos do Coração/fisiopatologia , Hipertensão/fisiopatologia , Hipertrofia Ventricular Esquerda/fisiopatologia , Masculino , Camundongos , Camundongos Knockout , Peptídeo Natriurético Encefálico/metabolismo , Pirimidinas/farmacologia , Ratos , Ratos Endogâmicos SHR , Receptor 5-HT2A de Serotonina/genética , Receptor 5-HT2A de Serotonina/metabolismo , Receptor 5-HT2B de Serotonina/genética , Receptor 5-HT2B de Serotonina/metabolismo , Disfunção Ventricular Esquerda/fisiopatologia
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