Objective To analyze the haemorheological related index changes in Han population in plain who returned from plat-eau about 45 d .Methods Venous blood of Han popuktion whe returned from plateau about 45 d and who stay in plain was collected for haemorheological related index detection .Results In males of Han population who returned to plains from plateau had a re-markable rising in HCT ,erythrocyte rigidity index and the whole blood viscosity of low shear rate (P<0 .05) .In females ,all indica-tors were higher than Han population stay in plain ,but not statistically different (P>0 .05) .Conclusion In males ,the plateau re-turned to plains Han population after returned to plain about 45 d ,most indexes of blood rheology can recover to the level of the people who stay in plain .In females ,all indexes of blood rheology can recover to the level of people who stay in plain .

Objective To study the changes of cardiac structure,heart function and pulmonary arterial pressure of the Han Chinese back to the plain after living long time on Tibetan Plateau. Methods Randomly choose 67 cases out of the Han people who have moved to the Tibetan Plateau many years , and been examined to make sure they have no disease caused by other factors. Examine their cardiac structure, heart function, pulmonary arterial pressure and valve flow velocity in Tibetan Plateau and about 60 days later back in plains respectively. Then make statistical analysis of high altitude cardiopulmonary adaptation and de-adaptation reaction according to the differences. Results Only were the values of pulmonary artery systolic pressure (PASP) and tricuspid regurgitation (TR) from the group back to plains lower than those from the group migrated to plateau (P = 0.045; P = 0.041). Other indicators of cardiac structure, heart function, pulmonary arterial pressure and valve flow velocity did not change significantly between the group back to plains and the group migrated to plateau (P > 0.05). Conclusions To Han people who returned to plains about 60 days later after long time staying on plateau , only the values of PASP and TR significantly reduce , which have not recovered to normal levels. This may be correlated with the ageing factor and long time migrating.

Objective To investigate the changes of red blood cells (RBC) and blood lipid in Han high altitude immigration dur‐ing the process of altitude acclimatization and their correlation .Methods Forty male Han nationality teachers entering Xizang Ali area and working for 1 year were selected .The blood samples were collected before entering plateau and within 3 d after returning to plain .The blood routine and the blood lipid level were detected .Results In the early return to plain ,the RBC ,TG ,CHO and LDL‐C levels in the research subjects were increased ,in which RBC and TG were significantly increased (P< 0 .01) ,HDL‐C was significantly decreased .After returning to plain ,RBC was positively correlated with TG and CHO (r=0 .46 ,P<0 .01 and r=0 .36 , P<0 .05) .Conclusion High altitude hypoxia environment is the primary cause leading to the change of RBC and blood lipid inde‐xes in the plain population after entering the plateau environment .