Changes in peripheral ?_1-adrenergic receptor sensitivity after high spinal cord injury in rats / 中华麻醉学杂志

ABSTRACT

Objective To evaluate the changes in peripheral?1-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 ?g?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 ?g?kg-1 were injected i.v. successively at an 1h 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, peripheral?1-adrenergic receptor sensitivity is significantly increased 3 weeks after high SCI.