RESUMO
40 rats were divided into 2 groups. At sea level and simulated high altitude of 4000m respectively, nalozone and saline are injected to observe the effect of nalozone on LVSP, LVDP, dp/dtmax, HR and survival time in hemorrhaged rats.blood plasma ?-EP is measured before and after bleeding to study the relation between ?-EP and hemorrhagic shock.Results: the circulatory parameters on hemorrhagic shock change more significantly at high altitude than at sea level; naloxone make these parameters recover and the survival time prolong both at sea level and high altitude; blood plasma ?-EP increases after bleeding, especially at high altitude-Suggestions; at high altitude hemorrbagic shock may be induced easilier.and symptomy is severer, development occurs rapider, and mortality higher is higher; change of ?-EP is related to the patholgical process of hemorhagic shock and the effect of ?-EP on cardiac contractility may be one of causes affecting bemorrbagic shock; naloxone has a role to antagonize hemorrhage shock at high altitude;