Methods One-day-old SD premature rats were randomly assigned to 4 groups:air+NS group(I),O-2+NS group(II),air+RA group(III),O-2+RA group(IV).

• 方法1日龄早产SD大鼠随机分为空气+生理盐水组(I组)、高氧+生理盐水组(II组)、空气+RA组(III组)、高氧+RA组(IV组)。