DOSE-RESPONSE OF L-NAME ON INTRATHECAL NITRIC OXIDE ACTIVITY AND SPINAL CORD BLOOD FLOW DURING TRANSIENT SPINAL CORD ISCHEMIA IN THE RAT

Abstract

S359 INTRODUCTION: The contribution of the increase in nitric oxide (NO) activity to the regional or whole brain ischemic injuries is widely accepted [1]. But it has been unclear whether NO activity has a correlation with spinal cord (SC) blood flow and injury level during and after SC ischemia. In this study, we tested whether lumbar intrathecal NO activity increased during transient SC ischemia and reperfusion in the rat. METHODS: After approval of the study protocol by the local ethical committee, 36 male Wistar rats were included in this study. They were divided into L10, L30, and Control (C) groups (n=12, each). Each group was further divided into NO or LD subgroups (n=6, each). In each rat anesthesia was induced by pentobarbital, 50 mg/kg, ip., and maintained by 0.7-1.5% halothane. Its trachea was intubated through tracheostomy and it was put on the artificial ventilator. PaCO2 was maintained between 35 and 40 mmHg during the study. Axial and femoral arterial pressures were continuously monitored through arterial catheter and an appropriate monitoring system. Left thoracotomy was made to place the tie around the descending aorta at T5 level to induce spinal cord ischemia. T11 through T13 laminectomy was made and dura was opened. NO subgroups were placed NO electrode intrathecally after calibration. NO activity was continuously determined by the NO meter (NO-501, Intermedical, Japan). LD subgroups were placed Laser Doppler Flow (LDF) meter (FLO-N1, Omega wave, Japan), and LDF was continuously determined L10, L30 and C groups were given Nw Nitro L-arginine methyl ester (L-NAME) (Sigma, St. Louis, U.S.A.), 10 mg/kg, 30 mg/kg, and saline, iv., respectively, 10 minutes before the 27 minutes' aortic clamp. Axial and femoral mean arterial pressure were controlled below 90 and 15 mmHg during the aortic clamp, respectively, and maintained at baseline values after declamp. NO activity changes and LDF were compared between groups at baseline, 27 min after clamp, at peak, 30 min, 60 min, and 120 min after declamp using ANOVA. P<0.05 was considered statistically significant. RESULTS: Main results were shown in Table 1.Table 1DISCUSSION: The results of this study shows that L-NAME attenuated the increase in NO activity during and after SC ischemia dose-dependently, but that blood flow was maintained in L10 group after transient SC ischemia more than the other groups.