EFFECTS OF CYANIDE ON THE NEURAL MECHANISMS CONTROLLING BREATHING IN THE NEONATAL RAT IN-VITRO

The effects of hydrogen cyan ide (HCN) on the neural mechanisms contro lling breathing were studied. Two in vitro experimental models were ut ilized: the brain stem-spinal cord and the medullary slice preparation s isolated from neonatal rats. Cyanide, at concentrations deemed letha l in vivo (50 mu M) caused a modest (< 15%) depression of the frequenc y and amplitude of inspiratory rhythmic discharge when added to the ba thing media. Moreover, the neuronal network underlying respiratory rhy thmogenesis continued to function for hours in the presence of very hi gh concentrations of cyanide (600 mu M). We hypothesize that the rapid suppression of breathing caused by cyanide in vivo is due to changes in neuronal excitability in respiratory modulating populations in the CNS rather than due to perturbations of cellular oxidative metabolism of neurons within respiratory rhythm generating centres. (C) 1995 Into x Press, Inc.