The Effect of Hypoxia on Oxidative Metabolism in the Early Postnatal Development of Rats

Abstract— The rate of oxygen consumption (VO₂) was measured during the first 7 days of postnatal development of newborn rats. During this period, in normoxia, VO₂ increased with increasing body weight (M), while the specific rate of oxygen consumption (Ψ) changed slightly. Hypoxia (10% O₂ for 40 min) caused a decrease in VO₂ in the first 4 days after birth. Later the change in VO₂ under hypoxia was insignificant. Hypoxia influenced on the coefficients of allometric equation: VO₂ = aM ^k. The coefficient k was equal to 0.74 in normoxia and 1.13 in hypoxia, and the coefficient a in hypoxia was lower than in normoxia. The ability to recover in normoxia after hypoxic exposure increased during the studied period of development. Thus, in newborn rats, the transition from hypoxic sensitivity to relative tolerance to hypoxia occurs within 1 week after birth.