pubmed-article:13774961 | pubmed:abstractText | The respiration of KCl-stimulated cortical slices of brain from control rats is markedly depressed by morphine, whereas the respiration of those from rats chronically dosed with morphine is unaffected. The results demonstrate an adaptation to morphine at the cellular level which is concomitant with the adaptation of the whole animal to morphine | lld:pubmed |