Binding sites for /sup 3/H-LTC4 in membranes from guinea pig ileal longitudinal muscle

Journal Article · Thu Mar 01 00:00:00 EST 1984 · Prostaglandins; (United States)

OSTI ID:6306017

Nicosia, S; Crowley, H J; Oliva, D; Welton, A F

Leutriene (LTC4) is one of the components of Slow Reacting Substance of Anaphylaxis (SRS-A) and is a potent constrictor of guinea pig ilea. The contraction is likely to be a receptor-mediated process. Here the authors report the existence of specific binding sites for /sup 3/H-LTC4 in a crude membrane preparation from guinea pig ileal longitudinal muscle. At 4 degrees C in the presence of 20 mM Serine-borate, binding increases linearly with protein concentration, reaches equilibrium in 10 minutes, and is reversible upon addition of 3 x 10(-5) M unlabelled LTC4. The dissociation curve is consistent with the existence of more than one class of binding site. Ca++ and Mg++ greatly enhance the binding of /sup 3/H-LTC4 at equilibrium. In the presence of 5 mM CaCl/sub 2/ and MgCl/sub 2/ not only LTC4 (IC50 10(-7)M), but also LTD4 and the SRS-A antagonist FPL 55712 can compete with /sup 3/H-LTC4 for its binding sites. FPL 55712 only displaces 60-70% of the total amount bound, while LTC4 displaces 90-95%. These studies indicate that multiple classes of binding sites exist for /sup 3/H-LTC4 in guinea pig ileal longitudinal muscle, and that at least part of these binding sites might be related to the ability of LTC4 to contract guinea pig ilea.

• Research Organization: Univ. of Milan, Italy
• OSTI ID: 6306017
• Journal Information: Prostaglandins; (United States), Vol. 27:3
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
PROSTAGLANDINS
RECEPTORS
SMALL INTESTINE
CONTRACTION
TRITIUM COMPOUNDS
BIOCHEMICAL REACTION KINETICS
CALCIUM CHLORIDES
CELL MEMBRANES
GUINEA PIGS
MAGNESIUM CHLORIDES
MUSCLES
ALKALINE EARTH METAL COMPOUNDS
ANIMALS
BODY
CALCIUM COMPOUNDS
CALCIUM HALIDES
CELL CONSTITUENTS
CHLORIDES
CHLORINE COMPOUNDS
DIGESTIVE SYSTEM
GASTROINTESTINAL TRACT
HALIDES
HALOGEN COMPOUNDS
INTESTINES
KINETICS
LABELLED COMPOUNDS
MAGNESIUM COMPOUNDS
MAMMALS
MEMBRANES
ORGANS
REACTION KINETICS
RODENTS
VERTEBRATES
551001* - Physiological Systems- Tracer Techniques