Fig. 11.   Peripheral defects evoked by prenatal nicotine exposure that contribute to hypoxia intolerance (Slotkin et al., 1995, 1997b). Low oxygen conditions elicit massive adrenal catecholamine release in 1-day-old control rats but no release occurs in animals exposed to nicotine prenatally. As a result, the nicotine group shows elevated mortality during hypoxia. The effects on cardiac function are evident within the first few minutes after initiation of low oxygen conditions: control rats show an initial increase in heart rate followed by a gradual decline to stable levels, whereas the nicotine group shows an immediate, precipitous decline in heart rate.