FUNCTIONAL OPIATE RECEPTORS IN THE GUINEA-PIG ILEUM - THEIR DIFFERENTIATION BY MEANS OF SELECTIVE TOLERANCE DEVELOPMENT

  • 1 January 1981
    • journal article
    • research article
    • Vol. 219  (2) , 547-550
Abstract
A differentiation of multiple opiate receptors in the electrically stimulated longitudinal muscle-myenteric plexus preparation of the guinea-pig ileum is described employing the technique of tolerance development of selective opiate receptors. Apparently, .mu.- and .kappa.-opiate receptors are clearly differentiated in this tissue, since highly tolerant .mu.-receptors (80-fold) coexist with .kappa.-receptors of almost normal sensitivity and vice versa. Attempts to demonstrate .delta.-receptors failed, as there was complete cross-tolerance between .mu.- and .delta.-agonists. Agonists bring about their action via .mu.-receptors in this preparation. Although .mu. and .kappa.-receptors have been demonstrated, neither of them appear to represent a uniform population.