心力衰竭大鼠增龄过程中β_3-肾上腺素能受体和内皮源性一氧化氮合酶表达变化的研究

Expression of beta3-adrenalin receptors and endothelium-derived nitricoxide synthase in heart failure rats with aging

目的:研究异丙肾上腺素诱导的心力衰竭大鼠随增龄β3肾上腺素能受体(β3受体)及其信号转导途径中相关基因内皮源性一氧化氮合酶(endomyocardialnitricoxidesynthase,eNOS)的表达,探讨β3受体和eNOS在老年大鼠心力衰竭中的作用。方法:将异丙肾上腺素诱导的心力衰竭大鼠存活者随机分为成年组(4月龄)、成年对照组、老年组(20月龄)、老年对照组(各7只)。①血流动力学测定。②免疫组化测β3受体蛋白和eNOS基因蛋白表达。③反转录多聚酶链反应(RT-PCR)方法测β3受体mRNA和eNOSmRNA表达。结果:①随增龄成年组和老年组比较,老年组左室收缩末压(LVendsys-tolicpressure,PES),左室压力最大上升速率(maximalratesofriseofventricularpressure,dp/dtmax),左室压力最大下降速度(maximalratesofdeclineofventricularpressure,dp/dtmin)绝对值较成年组明显降低犤PES:(72.3±5.7)和(93.7±9.6)mmHg;dp/dtmax:(7119±386)和(8352±339)mmHg/s;dp/dtmin:(-5011±380)和(-6143±534)mmHg/s,F=22.767,18.647,7.930,P均<0.05犦,左室等容舒张时间常数(constantofLVrelaxation,Tc)、左室舒张末压(LVenddiastolicpressure,PED)明显增加犤Tc:(22.21±2.53)和(16.44±1.49)ms,F=6.370,P<0.01;PED:(12.51±1.15)和(9.01±0.42)mmHg,

AIM:To study the expression and the function of aging on beta3-adrenalin receptor (β3-AR) of heart failure rats induced by isoproterenol and endomyocardia nitric oxide synthase (eNOS) correlated with β3-AR signaling.METHODS: Survival rats with heart failure induced by isoproterenol were randomly divided into four groups: adult group(n=7, 4 months old),adult control group(n=7), senile group(n=7, 20 months old) and senile control group(n=7). ①Hemodynamics were used to measure. ②Expression of β3-AR and eNOS proteins was identified by immunohistochemistry. ③The expression levels of β3-AR mRNA and eNOS mRNA were evaluated by reverse transcription-polymerase chain reaction (RT-PCR).RESULTS: ①Absolute values of LV end systolic pressure (PES), maximal rates of rise of ventricular pressure (dp/dtmax) and maximal rates of decline of ventricular pressure (dp/dtmin) in senile group were significantly lower than those in adult group [PES(72.3±5.7), (93.7±9.6) mm Hg; dp/dtmax : (7 119±386), (8 352±339) mm Hg/s; dp/dtmin: (-5 011±380), (-6 143±534) mm Hg/s, F=22.767, 18.647, 7.930; P< 0.05 respectively], and constant of LV relaxation (Tc), LV end diastolic pressure (PED) were significantly increased [Tc: (22.21±2.53), (16.44±1.49) ms, F=6.370, P< 0.01; PED: (12.51±1.15), (9.01±0.42) mm Hg, F=20.157, P< 0.05]. Compared with control group, hemodynamics was significantly aggravated in those two groups. ②Expression of β3-AR and eNOS proteins of positive cells in adult group were expressed increasingly with immunohistochemistry in heart failure rats compared with senile group, which was also higher than that in control group (t=6.861, 5.198, P< 0.05 to 0.01). ③The ratios of β3-AR mRNA and β-actin mRNA by RT-PCR in senile group (1.22±0.10) were higher than that in adult group (0.37±0.04) and senile control group (0.93±0.12). The ratios were higher in adult group than that in adult control group(0.23±0.07, F=4.792, P< 0.05). The ratios of eNOS mRNA and β-actin mRNA also tended to be higher with aging in heart failure rats(F=8.276, P=0.001). CONCLUSION: The expression of β3-AR and eNOS increases in failing heart rats with aging. If the levels of β3-AR and eNOS are too high, it contributes to the loss of cardiac function. So, the expression of β3-AR and eNOS increasing becomes one of the degradation factor in heart failure.