[Respiratory effects of nicotine and naloxone].

The effect of an i.v. bolus injection of nicotine 50 micrograms/kg-1, was compared in 6 awake dogs with the effect of nicotine injection after naloxone, 400 micrograms/kg-1. Respiratory inhibition was produced immediately after beginning the nicotine injection, followed by hyperpnea. Naloxone produced a significant decrease of the respiratory inhibition followed by hyperpnea increase compared to the trial with only nicotine.