Opiate and dopamine receptors in the isolated nictitating membrane of the cat

P. Illes, J. Knoll

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

Normorphine, methionine enkephalin methylester (MEM) and apomorphine inhibited the twitches of the isolated, field stimulated medial smooth muscle of the cat nictitating membrane without affecting the action of exogenous noradrenaline (9X10-6M). The activity of methionine and leucine enkephalin and enkephalin structure analogues was compared in the cat nictitating membrane and in the longitudinal muscle preparation of the guinea-pig ileum. In the nictitating membrane of the cat, both the morphine antagonist naloxone (2.7X10-7M) and the dopamine antagonist haloperidol (2.7X10-7M) counteracted significantly the depressant effects of normorphine (1.1x10-6M) and apomorphine (1.1X10-6M). However, the action of MEM (8.5X10-6M) could be antagonized only by naloxone (2.7X10-7M) and that of dopamine (1.6X10-5M) only by haloperidol (2.7X10-7M). Moreoever, tachyphylaxis to apomorphine and cross-tachyphylaxis between normorphine and apomorphine could be demonstrated. In the field stimulated longitudinal muscle preparation of the guinea-pig ileum, dopamine inhibited twitches only in extremely high concentrations and phentolamine (2.7X10-6M), but not haloperidol (8.1X10-7M), did antagonize the action of dopamine (1.6X10-4M). The isolated nictitating membrane of the cat seems to be a promising preparation for the analysis of the mechanism of action of opiates and opioid peptides, and morphine and dopamine receptors in this organ are similar in many respects.

Original languageEnglish
Pages (from-to)293-304
Number of pages12
JournalPolish journal of pharmacology and pharmacy
Volume30
Issue number2-3
Publication statusPublished - Dec 1 1978

ASJC Scopus subject areas

  • Pharmacology
  • Pharmaceutical Science

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