| Spinal cord injury (SC!) is a common disease in daily clinical practice of orthopedist. With a high rate of crippledom SC! threatens seriously peopl&s health and is taken into accounted by a lot of researchers. Unfortunately. up to now there is not a valid method to deal with it, all the measures taken in clinical practice result in poor effects. Spinal cord has such a poor power of regeneration that it can hardly restore the destoryed anatomic structure ,and in addition to a primary injury SCI includes a secondary injury which exacerbates the SCI. There is substantial evidence that a primary injury is the first factor causing SC!, and a secondary injury is the final factor deciding the extent of SCI, which may lead to irreversible deprivation of nervous functions. Secondary SC! is a perplexed process relating to multiple factors. Mechanism of vascular movement cooperating with mechanism of nervous biochemistry consists of the radical principle of secondary SC!. Many theories such as neurotoxity and microcirculation disorder were put forward, on which many means are tried to deal with secondary SC!, while the effects are dissatisfactory. There are so many factors cooperating in secondary SCI that we must find the most important link among them so as to solve the problem. Nitric oxide (NO), a new nervous medium, has been confirmed as an -7. important biological molecule with extensive biological effects in organisms. NO is catalyzed by Nitric Oxide Synthase (NOS) which is the key enzyme in the metablism of NO. In order to find the effect of NO in secondary SCI, we establish a model of compression injured spinal cord of rat to measure NOS activity and gene expression of its isforms in the spinal cord tissue by spectrophotometry and RT桺CR. The experiment is conducted as followings: I. At first we divide 30 healthy adult SD rats, weighing 220?00g. into six teams at random: normal, 2h after injury, 6h after injury, 12h after injury, 24h after injury and 48h after injury, five rats in each team. Then we establish model of spinal cord injury according to Nystrom?s method. 2. At different stipulated time, we take out injured spinal cord or corresponding section under anesthesia and asepsis, then measure the NOS activity by spectrophotometry. 3. At different stipulated time, we take out injuried spinal cord or corresponding section under anesthesia and asepsis , then measure the NOS isforms gene expression by RT桺CR. The results of study show that NOS activity is detected in normal spinal cord tissue, and after injury NOS activity in spinal cord tissue increases sharply with two peaks, one after 6 hours and another after 24 hours. nNOS mRNA and eNOS mRNA express in normal spinal cord tissue and their expressions increase quickly reaching the maximum 6 hours after injury. iNOS mRNA does not express in normal spinal cord tissue and its expression increases slowly reaching the maximum 24 hours after injury. The results indicate following conclusions: 1. NO participates, in the biological regulations of spinal cord tissue. 2. NO increases in injured spinal cord tissue, with two peaks 6h and 24h after injury respectively. 3. The three NOS isforms may lead to different effects on secondary Sc?...
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