EFFECT OF INCREASED F1O2 ON IUGR FETUS

Abstract

Since the growth retarded fetus(IUGR)is subjected to chronic hypoxia,we tested the effect of ↑ inspired oxygen cencentration in the maternal environment.The uterine artery of 29 pregnant rats was ligated at 17 days gestation;the other horn was left untouched resulting in AGA littermates. Rats were placed in cages designed to deliver either a constant f1O2 of 0.40(O2) or room air (RA). Both groups of rats gained weight equally.On day 21 the pregnant rat was injected ip with 3H2O to evaluate fetal fatty acid synthesis and returned to the same cage.Four hours later,fetuses were delivered.All fetuses from the ligated horn were rescrbed in 5 of 17 RA rats, while all 12 O2 rats had ≥ 2 surviving pups from the ligated horn.Survival was significantly ↑ (p<.05) in IUGR-O2 fetuses (57±8%,m+sem) compared to IUGR-RA group (33±6%). Data from IUGR fetuses are expressed as percentages of AGA littermates exposed to the same maternal environment.(Table) Fetal weight was significantly ↑ in the IUGR-O2 group compared to IUGR-RA fetuses, without a concomitant ↑ in the AGA-O2 group. 3H-fatty acid specific activity (SA) was significantly ↓ in IUGR-RA fetal liver, lung and carcass.Maternal O2 therapy resulted in a slight,although not statistically significant ↑ in fatty acid SA in all 3 organs.