Maternal nicotine exposure at doses ≥3.00 mg/kg/day decreased the number of successful autoresuscitations in 5- to 6-day-old rat pups exposed to intermittent hypoxia.
Does maternal nicotine exposure impair protective responses to hypoxia in newborn rats?
Maternal nicotine exposure above a specific threshold impairs the ability of newborn rats to autoresuscitate from intermittent hypoxia, suggesting a potential mechanism for vulnerability in human infants during sleep apnea or positional asphyxia.
Experiments were carried out to determine the threshold level of maternal nicotine that impairs protective responses of rat pups to hypoxia. From days 6 or 7 of gestation, pregnant rats received either vehicle or nicotine (1.50, 3.00, or 6.00 mg of nicotine tartrate. kg body wt(-1).day(-1)) or vehicle continuously via a subcutaneous osmotic minipump. On postnatal days 5 or 6, pups were exposed to a single period of hypoxia produced by breathing an anoxic gas mixture (97% N(2) or 3% CO(2)) and their time to last gasp was determined, or they were exposed to intermittent hypoxia and their ability to autoresuscitate from hypoxic-induced primary apnea was determined. Perinatal exposure to nicotine did not alter the time to last gasp or the total number of gasps when the pups were exposed to a single period of hypoxia. The number of successful autoresuscitations on repeated exposure to hypoxia was, however, decreased in pups whose dams had received either 3.00 or 6.00 mg of nicotine tartrate/kg body wt; these dosage regimens produced maternal serum nicotine concentrations of 19 +/- 6 and 35 +/- 8 ng/ml, respectively. Thus our experiments define the threshold level of maternal nicotine that significantly impairs protective responses of 5- to 6-day-old rat pups to intermittent hypoxia such as may occur in human infants during episodes of prolonged sleep apnea or positional asphyxia.
Fewell et al. (Tue,) conducted a other in Hypoxia response in newborn rats. Maternal nicotine exposure vs. Vehicle was evaluated on Time to last gasp and number of successful autoresuscitations on repeated exposure to hypoxia. Maternal nicotine exposure at doses ≥3.00 mg/kg/day decreased the number of successful autoresuscitations in 5- to 6-day-old rat pups exposed to intermittent hypoxia.