/sup 3/H-neurokinin A labels a specific tachykinin-binding site in the rat duodenal smooth muscle

Journal Article · Tue Dec 01 04:00:00 EST 1987 · Mol. Pharmacol.; (United States)

OSTI ID:5363039

Bergstroem, L B; Beaujouan, J C; Torrens, Y; Saffroy, M; Glowinski, J; Lavielle, S; Chassaing, G; Marquet, A; D'Orleans-Juste, P; Dion, S

/sup 3/H-Neurokinin A (/sup 3/H-NKA) with high specific activity (75 Ci/mmol) was synthesized to study NKA (NK-2)-binding sites on membrane preparations of various tissues in the rat, including brain, spinal cord, duodenum, vas deferens, and ileum. The binding capacity of /sup 3/H-NKA (0.9 nM) was very low in membrane preparations of different central nervous system regions and the ileum smooth muscle (0.2-2 fmol/mg of protein). In contrast, relatively high specific binding was found in membrane suspensions of the rat duodenal smooth muscle (18 fmol/mg of protein) and the vas deferens (8 fmol/mg of protein). /sup 3/H-NKA-binding sites were further characterized on the rat duodenal smooth muscle. The specific binding of /sup 3/H-NKA was shown to be temperature dependent, saturable, reversible, and increased in parallel with the protein concentration. Scatchard analyses and Hill plots of equilibrium binding studies in the concentration range of 0.40-30 nM revealed that /sup 3/H-NKA bound to a single class of noninteracting binding sites (Bmax = 270 fmol/mg of protein, KD = 13.3 nM). Displacement of /sup 3/H-NKA with different tachykinin-related peptides gave the following rank order of potencies: NKA greater than NKA (4-10) greater than kassinin greater than eledoisin greater than NKB much greater than substance P greater than physalaemin, which suggests that the binding site labeled by /sup 3/H-NKA is different from substance P (NK-1)-and NKB (NK-3)-binding sites. The biological activities of tachykinins and related peptides were tested by measuring their contractile effects on the rat duodenum and rabbit pulmonary artery, two tissues known to be sensitive for NKA. Ki values were correlated with the EC50 obtained in biological assays.

• OSTI ID: 5363039
• Journal Information: Mol. Pharmacol.; (United States), Journal Name: Mol. Pharmacol.; (United States) Vol. 32:6; ISSN MOPMA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIMALS
BIOCHEMICAL REACTION KINETICS
CELL CONSTITUENTS
CELL MEMBRANES
DISPERSIONS
IN VITRO
ISOTOPE APPLICATIONS
KINETICS
KININS
LABELLED COMPOUNDS
MAMMALS
MEMBRANE PROTEINS
MEMBRANES
MUSCLES
ORGANIC COMPOUNDS
PEPTIDES
POLYPEPTIDES
PROTEINS
RABBITS
RATS
REACTION KINETICS
RECEPTORS
RODENTS
SUSPENSIONS
TEMPERATURE DEPENDENCE
TRACER TECHNIQUES
TRITIUM COMPOUNDS
VERTEBRATES