<正> The effects of 7.5％ NaCl-6％ dextran 70 in small dosage on the cardiovascular func-tion and the survival rate in hemorrhagic shock at a simnlated altitude of 4000 m were observedin dogs.The animals were bled from the femoral artery for 8 rain to reduce the mean arterialpressure to 5.73±0.1kPa

which was maintained for an hour.Then the dogs were intravenouslyinjected with 4ml/kg 0.9％ NaCL（NS group

n=7）

7.5％ NaCl（HS group

n=6）and 7.5％Naa-6％ dextran 70（HSD group

n=6）respectively.In the 2-hour-period after injection

5out of 7 dogs of NS group died but only 1 out of the 6 of both the HS and HSD groupsdied.Significant increase of mean arterial pressure

left ventricular pressure

±dp/dt max of leftventricle

cardiac output

cardiac index and cardiac minute work index was observed in both theHS and HSD groups.Improvement of the cardiovascular function was even more marked inHSD group than in HS group

thougth the difference between the 2 groups was statisticallyinsignificant.There was a tendency for the pulmonary vascular resistance to decrease in HS andHSD groups as compared with the NS group.The percentage of plasma expansion of HSDgroup was larger than that of HS group（P<0.05）and of NS group（P<0.01）

but nosignificant difference existed between the HS and NS groups.It is believed that intravenous injection of hypertonic saline alone or in combination with dextran is effective for the treatment ofhemorrhagic shock at high altitude and the combination of 7.5％ NaCl and 6％ dextran 70seems even more effective.