Tropane ligands of different types of opiate receptors

: Interaction of tropane derivatives (motropin, atropine, cocaine) with opiates (morphine) and opioids (an enkephalin amide analog) was studied according to varying tests: pain sensitivity, impulse summation in the central nervous system, respiration. It appeared that motropin is a morphine antagonist and enkephalin amide analog from the standpoint of effect on analgetic action and impulse summation, but is not their antagonist as regards the effect on respiration. Atropine is a weak morphine antagonist in terms of the effect on analgesia, impulse summation and respiration as well. Cocaine is a morphine synergist as regards all the tests indicated. Therefore, the effect of tropane derivatives on pain sensitivity, impulse summation and respiration is mediated via different opiate receptors, which does not exclude the involvement of other neurochemical mechanisms in their action.