Background Renin-angiotensin-aldosterone system has been demonstrated to be associated with both congestive heart failure （CHF） and atrial fibrillation （AF）. This study investigated the effects of spironolactone, ...Background Renin-angiotensin-aldosterone system has been demonstrated to be associated with both congestive heart failure （CHF） and atrial fibrillation （AF）. This study investigated the effects of spironolactone, a kind of aldosterone antagonist, on atrial electrical remodeling and fibrosis in CHF dogs induced by chronic rapid ventricular pacing. Methods Twenty one dogs were randomly divided into sham-operated group, control group, and spironolactone group. In control group and spironolactone group, dogs were ventricular paced at 220 beats per minute for 6 weeks. Additionally, spironolactone at 15 mg.kgl.d1 was given to dogs 1 week before rapid ventricular pacing until pacing stopped. Transthoracic and transoesophageal echocardiographic examinations were performed to detect structural and functional changes of the atrium. Swan2 Ganz floating catheters were used to measure hemadynamics variances. Atrial effective refractory period （AERP）, AERP dispersion （AERPd） conduction velocity （CV） were determined. The inducib atrial fibrosis was quantified with Masson staining. intra- and inter-atrium conduction time （CT） and intra-atrium ity and duration of AF were also measured in all groups. Finally, Results AERP did not change significantly after dogs were ventricular paced for 6 weeks. However, AERPd, intra- and inter-atrium CT increased significantly, and CV decreased apparently, which was negatively correlated to the atrial fibrosis （r=-0.74, P〈0.05）. Simultaneously, left atriums were enlarged and cardiac hemadynamics worsened in pacing dogs. Although spironolactone could not affect cardiac hemadynamics effectively, it can obviously improve left atrial ejection fraction （P〈0.05）. Spironolactone treatment did not alter AERP duration, but this medicine dramatically decreased AERPd （P〈0.05）, shortened intra- and inter-atrium conduction time （P〈0.05）, and increased atrium CV. Moreover, spironolactone decreased the inducibility and duration of AF （P〈0.05）, as well as at展开更多
Background Stimulation of the heart β3-adrenoceptor （AR） may result in a negative inotropic effect. Being up-regulated, β3-AR plays a more important role in the regulation of cardiac function during heart failure....Background Stimulation of the heart β3-adrenoceptor （AR） may result in a negative inotropic effect. Being up-regulated, β3-AR plays a more important role in the regulation of cardiac function during heart failure. However, the effect of chronic blocking of β3-AR on heart failure has not been fully elucidated. In this study, we used a selective β3-AR antagonist SR59230A to treat a well defined heart failure rat model chronically, then evaluated its effect on cardiac function and investigated the mechanism. Methods Male Wistar rats were chosen randomly as controls （n=-8）. Isoproterenol induced heart failure rats were randomly divided into ISO group （n=-10） and SR group （n=10）. The ISO group received intraperitoneal injection of 1 ml saline twice a day; the SR group received intraperitoneal injection of SR59230A 85 nmol in 1 ml saline twice a day; and the control group received no treatment. The treatment was started 24 hours after the last isoproterenol injection and continued for 7 weeks. Then we measured the following indexes： the ratio of heart weight to body weight （HW/BW） and the ratio of left ventricular weight to body weight （LVW/BW）, collagen volume fraction （CVF）, left ventricular end diastolic dimension （LVEDd）, left ventricular end systolic dimension （LVESd）, ejection fraction （EF）, fractional shortening （FS） and the ratio of E wave to A wave （E/A）, the mRNA and protein expression of β3-AR and eNOS, and cGMP level in the heart. Results The ratios HW/BW and LVW/BW were significantly increased in the ISO group compared with the control group （P〈0.01）, but they were limited in the SR group （P〈0.05 compared with the ISO group）. CVF increased in the ISO group and the SR group （P〈0.01）, but it was significantly attenuated in the SR group （P〈0.01）. LVEDd, LVESd and E/A ratio were significantly increased in the ISO group compared with the control group （P〈0.01）, while EF and FS were significantly decreased （P〈0.01）. Compar展开更多
文摘Background Renin-angiotensin-aldosterone system has been demonstrated to be associated with both congestive heart failure （CHF） and atrial fibrillation （AF）. This study investigated the effects of spironolactone, a kind of aldosterone antagonist, on atrial electrical remodeling and fibrosis in CHF dogs induced by chronic rapid ventricular pacing. Methods Twenty one dogs were randomly divided into sham-operated group, control group, and spironolactone group. In control group and spironolactone group, dogs were ventricular paced at 220 beats per minute for 6 weeks. Additionally, spironolactone at 15 mg.kgl.d1 was given to dogs 1 week before rapid ventricular pacing until pacing stopped. Transthoracic and transoesophageal echocardiographic examinations were performed to detect structural and functional changes of the atrium. Swan2 Ganz floating catheters were used to measure hemadynamics variances. Atrial effective refractory period （AERP）, AERP dispersion （AERPd） conduction velocity （CV） were determined. The inducib atrial fibrosis was quantified with Masson staining. intra- and inter-atrium conduction time （CT） and intra-atrium ity and duration of AF were also measured in all groups. Finally, Results AERP did not change significantly after dogs were ventricular paced for 6 weeks. However, AERPd, intra- and inter-atrium CT increased significantly, and CV decreased apparently, which was negatively correlated to the atrial fibrosis （r=-0.74, P〈0.05）. Simultaneously, left atriums were enlarged and cardiac hemadynamics worsened in pacing dogs. Although spironolactone could not affect cardiac hemadynamics effectively, it can obviously improve left atrial ejection fraction （P〈0.05）. Spironolactone treatment did not alter AERP duration, but this medicine dramatically decreased AERPd （P〈0.05）, shortened intra- and inter-atrium conduction time （P〈0.05）, and increased atrium CV. Moreover, spironolactone decreased the inducibility and duration of AF （P〈0.05）, as well as at
基金This study was supported by grants from the Science and Technology Fund of Heilongjiang Education Bureau(No.11511228)the Innovation Fund of Harbin Medical University for Graduate Students(No.200401060)
文摘Background Stimulation of the heart β3-adrenoceptor （AR） may result in a negative inotropic effect. Being up-regulated, β3-AR plays a more important role in the regulation of cardiac function during heart failure. However, the effect of chronic blocking of β3-AR on heart failure has not been fully elucidated. In this study, we used a selective β3-AR antagonist SR59230A to treat a well defined heart failure rat model chronically, then evaluated its effect on cardiac function and investigated the mechanism. Methods Male Wistar rats were chosen randomly as controls （n=-8）. Isoproterenol induced heart failure rats were randomly divided into ISO group （n=-10） and SR group （n=10）. The ISO group received intraperitoneal injection of 1 ml saline twice a day; the SR group received intraperitoneal injection of SR59230A 85 nmol in 1 ml saline twice a day; and the control group received no treatment. The treatment was started 24 hours after the last isoproterenol injection and continued for 7 weeks. Then we measured the following indexes： the ratio of heart weight to body weight （HW/BW） and the ratio of left ventricular weight to body weight （LVW/BW）, collagen volume fraction （CVF）, left ventricular end diastolic dimension （LVEDd）, left ventricular end systolic dimension （LVESd）, ejection fraction （EF）, fractional shortening （FS） and the ratio of E wave to A wave （E/A）, the mRNA and protein expression of β3-AR and eNOS, and cGMP level in the heart. Results The ratios HW/BW and LVW/BW were significantly increased in the ISO group compared with the control group （P〈0.01）, but they were limited in the SR group （P〈0.05 compared with the ISO group）. CVF increased in the ISO group and the SR group （P〈0.01）, but it was significantly attenuated in the SR group （P〈0.01）. LVEDd, LVESd and E/A ratio were significantly increased in the ISO group compared with the control group （P〈0.01）, while EF and FS were significantly decreased （P〈0.01）. Compar
