自发性高血压大鼠左室心肌壁内小动脉平滑肌瞬时受体电位通道的表达

Expression of TRPC in the smooth muscle cells of the small intramyocardial arteries in the left ventricles of spontaneously hypertensive rats

目的:探索自发性高血压大鼠(Spontane-ously hypertensive rats,SHR)心肌壁内小动脉重构与瞬时受体电位通道(Transientreceptor po-tential channel,TRPC)蛋白表达的相关性。方法:24周龄雄性SHR(n=8)为实验组,设同周龄同性别正常血压大鼠为对照组(WKY,n=8)。计算大鼠左室质量指数(Left ventficular mass in-dex,LVMI)评价左室肥厚情况。采用HE染色观察管腔直径为10～69μm的左室心肌壁内小动脉结构特点并测定管腔面积(Lumen area,LA)、管壁面积(Wall area,WA)、管壁面积/管腔面积(WA/LA)。α-平滑肌肌动蛋白(Alpha-smooth muscle actin,α-SMA)免疫荧光染色鉴定血管平滑肌细胞(Vascularsmooth muscle cell,VSMC)。免疫荧光染色检测平滑肌细胞TR-PC1、TRPC3、TRPC5、TRPC6蛋白表达强度。结果:SHR组SBP及LVMI均明显高于WKY组[(200±4)vs(118±9)mm Hg,1mm Hg=0.133kPa;(3.11±0.03)vs(2.42±0.10)mg/g,均P<0.05];SHR组WA及WA/LA均比WKY组增加[(2951±224)vs(2654±190)μm2;(2.01±0.04)vs(1.53±0.03),均P<0.05],而LA比WKY组减少[(1469±117)vs(1730±98)μm2,P<0.05],α-SMA免疫荧光染色阳性表明增厚的血管中层为平滑肌细胞。SHR组心肌壁内小动脉平滑肌细胞TRPC1、TRPC3蛋白表达均明显高于WKY组(分别为65±8 vs 28±3和60±4 vs 26±8,均P<0.05),TRPC5蛋白表达与WKY组无统计学差异(28±7 vs 28±7,P>0.05);SHR组与WKY组均未表达TRPC6。结论:24周SHR左室心肌壁内小动脉平滑肌表达TRPC1、TRPC3、TRPC5而未表达TRPC6。24周SHR左室心肌壁内小动脉重构与平滑肌TRPC1、TRPC3表达上调相关。

AIM： To investigate the relation ship between the remodelling of small intramyocardial arteries （SIMAs） and the expression of transient receptor potential channel （TRPC） inspontaneously hypertensive rats （ SHR ）. METHODS. 24-weeks-old male of SHR taken as the experimental group （SHR group, n=8 ）, and the wistar kyoto rats （WKY, n=8） with matching age and male systolic blood pressure （SBP） is normal as the control group. Left ven- triclar mass index （LVMI） was calculated to e valuate the hypertrophy degree of the left ventri- cle. The structure feature of the small intramyo- cardial arteries with diameters from 10 to 69 μm in the left ventricles was evaluated with HE stai ning. The wall area （WA）, lumen area （LA）, wall area/lumen area （WA/LA） of SIMAs were measured. Vascular smooth muscle cells （VSMCs） were recognized with alpha-smooth muscle actin （α-SMA） immunofluorescence stai- ning. The expression of TRPC1, TRPC3, TR- PCS, TRPC6 were also detected with immuno- fluorescence staining. RESULTS. Both SBP and LVMI of the SHR group were significantly high- er than those in WKY group （（200±4） vs （118 ±9） mm Hg;（3.11±0.03） vs （2.42±0.10） mg/g respectively, both P〈0.051. Both WA and WA/LA of the SHR group were larger than those in WKY group（（2951±224） vs （2654±190） μm2 ; （2.01±0.04） vs （1.53±0.03） ,bothP 〈 0.05 1. However, LA of the SHR group was smaller than that of WKY group（（1469± 117） vs （1730±98） μm2,P〈0.05]. Positive α- SMA immunofluorescence staining indicated that the thickening middle layer of the SIMAs was smooth muscle cells. The expressions of TRPC1 and TRPC3 on the SIMAs of SHR group were significantly higher than those in WKY group （65±8 vs 28±3 and 60±4 vs 26±8 respective- ly,both P〈0.05）. The expressions of TRPC5 in two groups were not statistically different（28 ±7 vs 28±7,P〉0.05）. TRPC6 was not ex- pressed on the SIMAs in both groups. CONCLU- SION： The smooth muscle cells of the small in tramyocardial arteries in 24-weeks-old SHR ex- presses TRPC1, TRPC3 and TRPC5 but not TR- PC6. The remodelling of the small intramyocar- dial arteries in SHR is associated with the up- regulation of TRPC1 and TRPC3.