关键词: 高原鼠兔 Wistar 大鼠 一氧化氮（NO） 内皮素-1（ET -1）

Abstract: The aim of the present study was to compare the effects of hypoxia on NO，ET_-1 and NO/ ET_-1 levels in Wistar rats and pikas. We determined NO and ET_-1 levels in the serum of 30 rats（three groups of 10 rats，each taken to 3 780 m and divided into 24 h，2 wk and 3 wk durations）and 10 pikas at 3 780 m by ELISA and Nitrate Reductase Method. We compared the values of NO，ET _-1 and NO/ ET_-1 in rats of 24 h duration with those in rats of 2 wk and 3 wk durations. We then compared NO，ET_-1 and NO/ ET_-1 values in the 24 h，2 wk，3 wk groups with those in pikas. In the beginning of entry to high altitude，the NO and ET_-1 levels in rats were markedly increased compared to those in pikas（respectively，P <0. 01），whereas the values of NO/ ET_-1 in rats and pikas were very close（P > 0. 05）. There was a decreasing trend in NO levels and an increasing trend in ET _-1 levels（respectively，P < 0. 01）with passage of time at high altitude in rats，and NO was well correlated with ET _-1（r² = 0. 2416，P < 0. 01）. The NO/ ET_-1 levels in pikas was approximately 2 fold greater than in the 2 wk and 3 wk groups（ P < 0. 01）. In conclusion，NO，ET_-1 and NO/ ET_-1 levles in Wistar rats and pikas at 3 780 m are very different，may indicate adaption or acclimitization to high altitude hypoxia.

Key words: Endothelin -1(ET -1), Hypoxia rat, Nitric oxide(NO), Pika