Maternal smoking is a major risk factor for SIDS. We have previously shown that prenatal nicotine exposure impairs the cardiorespiratory response to acute hypoxemia in sleeping young lambs (Pediatr Res 41:302A, 1997). The aim of this study was to determine whether this effect is mediated by a dopaminergic mechanism.

Subjects & Methods. Seven pregnant ewes were infused continously with nicotine, 40 mg/d during the last trimester. Nicotine conc. was 6.7±1.0 ng/ml. Seven nicotine exposed lambs (N)and 7 control lambs(C) were studied at a postnatal age of 3 to 10 d. Hypoxia tests (change in FiO2 to 0.1 for 4 min) were performed in quiet sleep during infusion of a) saline, b) domperidone (DP), a DA2 receptor blocker in the carotid bodies or c) SCH 23390 (SCH), a DA1 receptor blocker in the brainstem.

Results. Ventilation increased less in N compared with C. This attenuated response was significantly reversed by SCH. In 4 C lambs, DP reduced the response slightly, while a significant attenuation was observed with SCH (p<0.05). Table

Table 1 Hypoxia tests (% change in minute ventilation from baseline)(Mean+SD)
Full size table

Conclusion. Prenatal nicotine exposure has a marked inhibitory effect on the postnatal ventilatory response to hypoxemia which appears to mediated by a dopaminergic mechanism.