Effects on the isolated human bronchus of SR 48968, a potent and selective nonpeptide antagonist of the neurokinin A (NK2) receptors

Am Rev Respir Dis. 1992 Nov;146(5 Pt 1):1177-81. doi: 10.1164/ajrccm/146.5_Pt_1.1177.

Abstract

Tachykinins produce concentration-dependent contraction of the human isolated bronchus by stimulation of receptors that belong to the NK2 type. The aim of this study was to investigate the inhibitory effects of a new, potent, and selective nonpeptide antagonist of the neurokinin A (NKA) (NK2) receptors, SR 48968 [(S)-N-methyl-N-[4-acetylamino-4-phenylpiperidino-2-(3,4-dichlorophenyl) butyl]benzamide] on human isolated airways. Our experiments were performed on human isolated bronchi obtained from patients with lung cancer. Phosphoramidon, 10(-5) M, was added to the bath to inhibit neurokinin metabolism. SR 48968 induced a parallel shift to the right of the concentration-response (C/R) curves to [Nle10]-NKA(4-10), a specific NK2 receptor agonist. The antagonism was of the competitive type, with a pA2 of 9.40 +/- 0.19 (slope = 0.95 +/- 0.08, n = 13). The (R)-enantiomer of SR 48968 was 100-fold less potent and a noncompetitive antagonist (slope = 0.56 +/- 0.11, n = 8); pA2 and slope of the racemate were 8.86 +/- 0.21 and 1.09 +/- 0.21 (n = 7), respectively. Under similar conditions, racemic CP-96,345, a nonpeptide NK1 antagonist, did not modify the C/R curves to [Nle10]-NKA(4-10) until 10(-7) M. SR 48968 did not modify C/R curves to acetylcholine, histamine, KCI, or PGF2 alpha on the human isolated bronchus. Finally, SR 48968 shifted to the right C/R curves to substance P on isolated human bronchi, whereas racemic CP-96,345 was without effect.(ABSTRACT TRUNCATED AT 250 WORDS)

MeSH terms

  • Acetylcholine / administration & dosage
  • Acetylcholine / pharmacology
  • Amino Acid Sequence
  • Animals
  • Benzamides / administration & dosage
  • Benzamides / chemistry
  • Benzamides / pharmacology*
  • Biphenyl Compounds / pharmacology
  • Bronchi / drug effects*
  • Bronchoconstriction / drug effects
  • Cricetinae
  • Dinoprost / administration & dosage
  • Dinoprost / pharmacology
  • Dose-Response Relationship, Drug
  • Drug Antagonism
  • Drug Evaluation, Preclinical
  • Female
  • Histamine / administration & dosage
  • Histamine / pharmacology
  • Humans
  • In Vitro Techniques
  • Male
  • Middle Aged
  • Molecular Sequence Data
  • Neurokinin A / antagonists & inhibitors*
  • Neurokinin A / drug effects
  • Peptide Fragments / drug effects
  • Piperidines / administration & dosage
  • Piperidines / chemistry
  • Piperidines / pharmacology*
  • Potassium Chloride / administration & dosage
  • Potassium Chloride / pharmacology
  • Racemases and Epimerases
  • Receptors, Neurokinin-2
  • Receptors, Neurotransmitter / classification
  • Receptors, Neurotransmitter / drug effects*

Substances

  • Benzamides
  • Biphenyl Compounds
  • Peptide Fragments
  • Piperidines
  • Receptors, Neurokinin-2
  • Receptors, Neurotransmitter
  • Potassium Chloride
  • SR 48968
  • Histamine
  • Neurokinin A
  • neurokinin A(4-10)
  • Dinoprost
  • Racemases and Epimerases
  • Acetylcholine
  • CP 96345