The sensitivity of the respiratory center and some circulatory and subjective responses after nalorphine and naloxone injections.

In five volunteers the sensitivity of the respiratory centre to carbon dioxide after naloxone and nalorphine injections was studied using "double blind" method and increments of doses. Alterations in the respiratory centre sensitivity were reflected by changes in respiratory minute volume, which was measured before and after drug injections, as well as after carbon dioxide stimulation. Comparison of results and their statistical verification showed that nalorphine alone causes respiratory depression and carbon dioxide stimulation is, beside the weak initial action, almost ineffective. Naloxone causes very small, if at all, respiratory depression and the respiratory centre answers efficiently to carbon dioxide stimulation.