Brundage Cord M, Taylor Barbara E
Institute of Arctic Biology, Department of Biology and Wildlife, University of Alaska Fairbanks, Fairbanks, AK, USA.
Dev Neurobiol. 2009 Jun;69(7):451-61. doi: 10.1002/dneu.20720.
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.
呼吸空气的脊椎动物根据二氧化碳增加（高碳酸血症）来调节通气的能力对于维持pH值稳态至关重要。研究表明，发育过程中接触尼古丁8至12周后，蝌蚪对高碳酸血症的神经通气反应会受损。然而，尚不清楚发育过程中接触尼古丁的时间以及/或者接触持续时间在多大程度上导致了这种损害。在此，将蝌蚪在发育早期或晚期暴露于30微克/升的尼古丁中，持续3周或10周。在离体脑干的正常碳酸血症（1.5%二氧化碳）和高碳酸血症（5%二氧化碳）条件下监测蝌蚪肺神经通气的相关指标。无论早期变态蝌蚪暴露于尼古丁3周还是10周，其制备物均未能对高碳酸血症增加肺神经通气做出反应。晚期变态蝌蚪的制备物在暴露于尼古丁10周后对高碳酸血症无反应。这些结果表明，在考虑尼古丁对高碳酸血症神经通气反应的影响时，发育时间和暴露持续时间都很重要。
