PRENATAL COCAINE - EFFECT ON HYPOXIC VENTILATORY RESPONSIVENESS IN NEONATAL RATS

The effects of prenatal (embryonic days 7-21) cocaine (30 mg/kg b.i.d. , s.c.) exposure on postnatal respiratory and behavioral responsivenes s to acute hypoxia were investigated in 5-day-old (P5) rat pups. Contr ol and cocaine-exposed pups were subjected to 20 min of 0.21 Fl(O2) fo llowed by 20 min of 0.08 Fl(O2). Although all pups demonstrated the ch aracteristic biphasic response to hypoxia, cocaine-exposed pups exhibi ted a blunted initial response in minute ventilation (p <0.05) and ins piratory drive (p <0.05) as compared with control pups who showed incr eases in these measures (p <0.01 and p <0.05, respectively). The conse quence of this apparent blunted ventilatory response was reflected in blood gas data gathered after 20 min of 0.08 Fl(O2): P-CO2 (P <0.05) a nd base-excess (p <0.05) were increased and HCO3- (p <0.05) and S-O2 ( P <0.01) were decreased relative to control pups. Cocaine-exposed pups also exhibited behavioral evidence of decreased struggling (p <0.001) in response to the hypoxic challenge. These data in the rat confirm o ur previous findings of altered ventilatory responsiveness to inspired hypoxia in the rabbit and extend our observations of a decreased abil ity to successfully compensate and behaviorally arouse following prena tal cocaine-exposure, thus underscoring the potential vulnerability of infants so exposed.