THE CARDIORESPIRATORY RESPONSE TO ANOXIA - NORMAL DEVELOPMENT AND THEEFFECT OF NICOTINE

Maternal smoking increases the risk of the sudden infant death syndrom e (SIDS) 2-4-fold. The mechanism is unknown but may be related to hypo xia responses. Recovery from hypoxic apnea by young mammals depends on gasping and bradycardia. We asked whether prenatal nicotine exposure, reported to reduce hypoxic survival in 2 day old rat pups, acted by i mpairing gasping or bradycardia. Pregnant rats were infused throughout gestation and 1 week postnatally with nicotine tartrate (NIC) 12 mg/k g per day or saline (CON). Maternal plasma nicotine was 134.4 +/- 42 n g/ml, significantly reducing pup body weight. Pups at 3-28 days were e xposed to anoxia (97% N-2/3% CO2) until gasping ceased, while breathin g and heart rate were recorded. NIC and CON groups were not significan tly different at any age, in baseline heart rate, respiratory rate, th e time course for bradycardia, time to gasp onset, duration of gasping , or number of gasps, although most of these variables declined signif icantly with age. We conclude that responses to anoxia are not affecte d by prenatal high-dose nicotine. (C) 1997 Elsevier Science B.V.