The protective effect of ketamine on circulatory system disorders after high-lever spinal cord injury in rats

Abstract

Objective To study the protective effect of ketamine(KT) on circulatory system disorders after high-level spinal cord injury (SCI) in rats.Methods Twenty male 18-week-old SD rats weighing 290 g-310 g were randomly divided into 4 groups (n=5):SCI group,SCI+KT group,Sham group and Sham+KT group.The animals in SCI and SCI+KT groups were subjected to SCI at T4 according to modified Allen's method.The operations for Sham group and Sham+KT group were preformed without stroking spinal cord.Twenty-four hours after the operation,SCI+KT group and Sham+KT group were treated with ketamine 1 mg·kg-1 ·d-1,daily lasting 6 weeks.Mean arterial pressure(MAP),heat rate(HR) and the level of noradenaline(NA) in urine were recorded once a week for 6 weeks.At the end of 6 weeks post operation,left ventricular internal pressure maximum rate of change (-±dp/dtmax) were recorded and myocardial specimen was sampled from left ventricle to study myocardial histology with HE staining.Results In SCI group,the animal's MAP[(90±4) mmHg(1 mmHg=0.133 kPa)] and NA level were significantly lower and HR[(518±11) bpm] were significantly faster starting from 1 week post SCI compared with Sham group.Left ventricular internal pressure maximum rising rate (+dp/dtmax) were significantly increased 6 weeks post SCI.However,in SCI+KT group,the animals' MAP increased to (106±4) mmHg,HR decreased to (459±10) bpm,and +dp/dtmax and NA lever changed significantly (P＜0.05).Ultrastructure Of myocardial tissue presented abnormal changes in SCI groups,but the changes in SCI+KT group were milder.Conclusions High-level spinal cord injury could induce the disorders of circulatory system.Ketamine can increase NA lever and improve hemodynamics and myocardial function after SCI. Key words: Spinal cord injury; Ketamine; Noradrenaline ; Circulatory system