Oxygen consumption and survival prediction in neonatal rats exposed to prenatal hypervitaminosis A

Publisher Website
Google Scholar
Abstract
Fetal exposure to excess vitamin A results in a highly variable degree of lung pathology and high neonatal mortality in the Long–Evans rat. The present study evaluated O2 consumption in newborn of vitamin A‐treated, vehicle‐treated, and untreated pregnancies on five consecutive postnatal days beginning with the day of delivery (D0). Pregnant female rats were treated by gavage with 160,000 USP units of retinyl acetate dissolved in 0.5 ml corn oil on days 15 through 19 of gestation. Vehicle and undisturbed controls were run concurrently. All animals delivered spontaneously, and the pups were tattooed and individually tested in a closed system consisting of three chambers submerged within a thermostatically controlled water bath at 33°C. Vitamin A‐exposed pups, as a group, have significantly lower QO2 (ml O2 consumed/min/kg body weight) values than controls through postnatal day 2 (p < 0.05). By days 3 and 4 of age, the mean QO2 values of surviving vitamin A‐treated pups were similar to those of controls. A QO2 of 30 or greater on day 0 appears to be critical for early neonatal survival of vitamin A‐exposed pups, as 87% of the pups with initial QO2 < 30 died prior to day 4. Oxygen consumption rates in teratogen‐exposed pups exhibiting low QO2 on day 0 rarely reached normal levels. In contrast, the occasional control pup with such low initial levels were well within normal limits (X̄ ± 1 SD) by the following day. These studies demonstrate a marked effect of prenatal insult on respiratory function and strongly suggest that the nonivasive determination of QO2, 2–6 hours after birth provides a means to identify both moderately and severely affected individuals thereby permitting sequential study of their ensuing development of atelectasis neonatorum and apparent hyalin membrane disease.