Effect of antimorphine antibodies on an in vitro correlate of antagonist-precipitated opiate abstinence.

Antimorphine globulin was used to study the mechanism by which naloxone produces a contracture in ileal strips removed from morphine pellet-implanted guinea pigs. Although the antibodies effectively reversed the depressant actions of morphine on electrically stimulated contractions in both naive and tolerant tissues, neither monkey antimorphine (Kd = 1.43 x 10(-7)M) nor goat antimorphine (Kd = 1.36 x 10(-9)M) were able to elicit a naloxone-like contracture. The rate of attenuation of tissue sensitivity to naloxone was measured and no changes were observed after incubation in the presence of monkey antimorphine globulin. High-affinity goat antimorphine globulin, however, was able to accelerate the rate of attenuation of tissue sensitivity to naloxone. The naloxone contracture was accompanied by release of material reactive with morphine antiserum in a radioimmunoassay. The quantities of material were in excess of what could be bound by opiate receptors present in the tissue. Possible mechanisms of naloxone sensitivity observed in the isolated ileum are discussed.