Timing and duration of developmental nicotine exposure contribute to attenuation of the tadpole hypercapnic neuroventilatory response.
The ability for air-breathing vertebrates to adjust ventilation in response to increased CO(2) (hypercapnia) is fundamental to maintaining pH homeostasis. Developmental nicotine exposure has been shown to impair tadpole neuroventilatory responses to hypercapnia following 8-12 weeks of exposure. It is not clear, however, to what extent the timing of exposure during development and/or the duration over which the exposure takes place contribute to this impairment. Here, tadpoles were exposed to 30 microg/L of nicotine for 3- or 10-week durations, either early or late in tadpole development. Correlates of tadpole lung neuroventilation were monitored during normocapnic (1.5% CO(2)) and hypercapnic (5% CO(2)) conditions of isolated brainstems. Preparations derived from early metamorphic tadpoles failed to increase lung neuroventilation in response to hypercapnia whether they had been exposed to nicotine for 3 or 10 weeks. Preparations derived from late metamorphic tadpoles failed to respond to hypercapnia after being exposed to nicotine for 10 weeks. These results suggest that both the developmental timing and duration of exposure are important when considering nicotine's effect on the hypercapnic neuroventilatory response.
Institute of Arctic Biology, Department of Biology and Wildlife, University of Alaska Fairbanks, Fairbanks, AK, USA.
Cord M
CM
Brundage
Barbara E
BE
Taylor
D000367:Age Factors; D000704:Analysis of Variance; D000818:Animals; D001933:Brain Stem / Q000187:drug effects / Q000503:physiopathology*; D004594:Electrophysiology; D005154:Facial Nerve / Q000187:drug effects / Q000503:physiopathology; D006935:Hypercapnia / Q000503:physiopathology*; D007002:Hypoglossal Nerve / Q000187:drug effects / Q000503:physiopathology; D007814:Larva; D008168:Lung / Q000187:drug effects / Q000503:physiopathology; D008675:Metamorphosis, Biological / Q000187:drug effects*; D009538:Nicotine / Q000008:administration & dosage / Q000494:pharmacology*; D018722:Nicotinic Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D016897:Respiratory Burst / Q000187:drug effects*; D015656:Respiratory Mechanics / Q000187:drug effects; D013997:Time Factors
D018722:Nicotinic Agonists; D009538:Nicotine