高位脊髓损伤大鼠外周α_1-肾上腺素受体敏感性的变化

Changes in peripheral α_1-adrenergic receptor sensitivity after high spinal cord injury in rats

目的评价高位脊髓损伤大鼠外周α1-肾上腺素受体敏感性的变化。方法健康雄性 Wistar大鼠30只,随机分为脊髓损伤组(L组,n=24)和对照组(C组,n=6)。L组大鼠采用改良Allens 打击法建立脊髓胸4节段损伤动物模型,术后3周随机分为4个亚组(n=6),分别静脉注射苯福林1 μg/kg(P1亚组)、2μg/kg(P2亚组)、3μg/kg(P3亚组)和4μg/kg(P4亚组),C组亦分次分别静脉注射苯福林1、2、3和4μg/kg,观察注药前、后大鼠心率、收缩压及舒张压的变化。结果与C组比较,L组大鼠给药前体重减轻、心率减慢,收缩压和舒张压降低。与基础值比较,C组和L组给药后心率减慢, 收缩压和舒张压升高。与C组比较,L组给药后心率、收缩压、舒张压变化率增高(P<0．05或0．01)。结论高位脊髓损伤后,大鼠外周α-肾上腺素受体敏感性增强。

Objective To evaluate the changes in peripherala1-adrenergic receptor sensitivity in a rat model of chronic high spinal cord injury （SCI）Methods Thirty male 18-week-old Wistar rats weighing 290-310g were randomly divided into 2 groups： SCI group （n = 24） and control group （C n = 6） . The animals were anesthetized with intraperitoneal 2 % pentobartital 50 mg·kg^-1 and subjected to spinal cord injury （SCI） at T4 according to modified Allen＇s method. Successful high SCI was confirmed by bilateral hindlimb flaccid paralysis. Three weeks after SCI the animals were further divided into 4 subgroups （ n = 6） receiving 4 different doses of phenylephrine 1, 2, 3 and 4 μg·kg^-1 i.v. Femoral artery was connulated for BP （SBP and DBP） and HR monitoring. HR and SBP and DBP were recorded before and after i.v. phenylephrine injection. In control group phenylephrine （PE） 1, 2, 3 and 4 μg·kg^-1 were injected i.v. successively at an lh interval. % changes in HR, SBP and DBP were calculated： % change = （post-injection value - baseline value） / baseline value. Results The animals lost weight and HR was significantly slower and SBP and DBP were significantly lower 3 weeks after SCI as compared with control group. In both group C and SCI, HR was significantly decreased and SBP and DBP were significantly increased after i.v. PE injection as compared to the baseline value before PE. The % changes in HR, SBP and DBP were significantly greater in group SCI than in group C. Conclusion In a rat model of chronic high SCI, peripherala1-adrenergic receptor sensitivity is significantly increased 3 weeks after high SCI.