Kappa opioid partial agonist activity of the enkephalin-like pentapeptide BW942C based on urination and in vitro studies in humans and animals

D. B. Vaupel, E. J. Cone, R. E. Johnson, T. P. Su

Research output: Contribution to journalArticle

Abstract

A diuretic effect of the pentapeptide BW 942C [Tyr-D-Met(O)-Gly-pNO2-Phe-Pro-NH2 HCI] was demonstrated in humans and rats; it was characterized pharmacologically using whole animal, isolated tissue and in vitro binding studies. A single 2-mg dose of BW942C increased urine output 5-fold over control values in humans. In Long-Evans rats, BW942C produced a biphasic dose-response curve for urine output with lower doses increasing and higher doses suppressing output. Low doses of naltrexone antagonized the antidiuresis, and high doses antagonized the diuresis produced by BW942C. BW942C was less efficacious in producing diuresis than the full kappa agonists bremazocine and U50,488H (trans-3,4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl)-cyclohexyl]- benzeneacetamide methanesulfonate, hydrate). Furthermore, BW942C antagonized the diuretic effects of bremazocine and U50,488H. Rats tolerant to U50,488H-induced diuresis were cross-tolerant to BW942C. In Brattleboro rats, which are unable to synthesize vasopressin, BW942C failed to produce a diuretic effect, demonstrating the necessity of vasopressin for its diuretic response. In the kappa-selective rabbit vas deferens bioassay, BW942C was less efficacious than a full agonist, it was antagonized by naloxone and BW942C in nondepressant doses antagonized a full agonist. In binding studies, BW942C had the highest affinity for mu and delta opioid receptors and an intermediate affinity for kappa opioid receptors. The data suggest that BW942C has the property of a partial kappa opioid agonist in addition to being a mu agonist.

Original languageEnglish (US)
Pages (from-to)225-234
Number of pages10
JournalJournal of Pharmacology and Experimental Therapeutics
Volume252
Issue number1
StatePublished - 1990

ASJC Scopus subject areas

  • Molecular Medicine
  • Pharmacology

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