EFFECT OF NICOTINE EXPOSURE ON POSTNATAL VENTILATORY RESPONSES TO HYPOXIA AND HYPERCAPNIA

The risk of SIDS is increased up to fourfold by maternal smoking, by a n unknown mechanism We tested the hypothesis that prenatal nicotine ex posure can cause abnormal postnatal development of breathing control. Osmotic minipumps were implanted into pregnant rats to deliver either nicotine bitartrate (6 mg kg(-1) day(-1)) (NIC) or saline (CON) throug hout gestation and for 1 week postnatal. NIC and CON rat pups from 4 a ge groups (means 3, 8, 18 and 34 days) were studied. Ventilation was r ecorded at 30 degrees C in air and after 10 min at FIO2 = 0.1 and 0.15 , and at FICO2 = 0.05 Ventilatory responses to FIO2 = 0.1 and FICO2 = 0.05 showed significant changes with age but were unaffected by NIC at all ages. The weak respiratory responses to FIO2 = 0.15 were unaffect ed by NIC or age. Oxygen consumption in normoxia and hypoxia, and hypo xic depression of oxygen consumption, declined with age but were not a ffected by NIC. We conclude that MC exposure alone has no detectable e ffect on the postnatal development of respiratory responses to moderat e levels of hypoxia or hypercapnia for short periods. However, effects of MC on the responses to more severe or prolonged stimuli cannot be ruled out.