A comparative study of the morphine effect on the level of cyclic AMP in lymphocytes of smokers and nonsmokers.

A study of the effect of morphine on the level of cAMP in the lymphocytes of peripheral blood in smokers and nonsmokers was carried out. It was shown that morphine enhances the activity of adenylate cyclase, and that this effect can be abolished by naloxone. The dependence of the enzyme activity on the concentration of morphine is complex. The maximal effect of the investigated opiate on the level of cAMP in lymphocytes occurs among smokers at a tenfold concentration compared with nonsmokers. On the basis of our data two suggestions are made: (i) there are opiate receptors on lymphocytes with a mechanism of action connected with the regulation of adenylate cyclase activity; (ii) smoking develops tolerance to morphine at the level of the opiate-dependent adenylate cyclase of lymphocytes.