Characterization of guinea pig myocardial leukotriene C4 binding sites. Regulation by cations and sulfhydryl-directed reagents
Using (/sup 3/H)leukotriene C4 (LTC4) and radioligand-binding techniques, specific leukotriene C4 binding sites have been identified in membranes derived from guinea pig ventricular myocardium. High performance liquid chromatography analyses indicated that, in the presence of the gamma-glutamyl transpeptidase inhibitor L-serine-borate (80 mM), less than 2% of membrane-bound (/sup 3/H)LTC4 was converted at 20 degrees to (/sup 3/H)leukotriene D4 or (/sup 3/H)leukotriene E4. The specific binding of 4 nM (/sup 3/H)LTC4, in the presence of 80 mM L-serine-borate, reached a stable steady state within 15 min at 20 degrees (pH 7.5). A monophasic Scatchard plot of saturation binding data yielded a dissociation constant (Kd) of 27.5 +/- 6.0 nM and a maximum number of binding sites (Bmax) of 19.9 +/- 5.2 pmol/mg of membrane protein. Competition binding studies of (/sup 3/H)LTC4 with synthetic leukotriene C4, leukotriene D4, and leukotriene E4 and the putative peptidoleukotriene antagonists FPL 55712, SKF 88046, and 4R-hydroxy-5S-1-cysteinylglycine-6Z-nonadecanoic acid revealed an order of potency of leukotriene C4 much greater than 4R-hydroxy-5S-1-cysteinylglycine-6Z-nonadecanoic acid greater than SKF 88046 greater than LTE4 greater than LTD4 greater than FPL 55712. The specific (/sup 3/H)LTC4 binding was stimulated by the divalent cations Ca2+, Mg2+, and Mn2+ and to a lesser degree by the monovalent cations Na+, K+, Li+, and NH4+. CaCl2 (3 mM) and NaCl (150 mM) stimulated the LTC4 binding by increasing the Bmax to 42.6 +/- 5.9 and 35.0 +/- 2.0 pmol/mg, respectively, but had minimal effects on Kd.
- Research Organization:
- Smith Kline and French Labs., Philadelphia, PA
- OSTI ID:
- 5609804
- Journal Information:
- Mol. Pharmacol.; (United States), Journal Name: Mol. Pharmacol.; (United States) Vol. 27:2; ISSN MOPMA
- Country of Publication:
- United States
- Language:
- English
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59 BASIC BIOLOGICAL SCIENCES
ALKALI METAL COMPOUNDS
ALKALINE EARTH METAL COMPOUNDS
AMMONIUM COMPOUNDS
ANIMALS
ARACHIDONIC ACID
BODY
CALCIUM COMPOUNDS
CARBOXYLIC ACIDS
CARDIOVASCULAR SYSTEM
CATIONS
CELL CONSTITUENTS
CELL MEMBRANES
CHARGED PARTICLES
CHEMICAL BONDS
CHROMATOGRAPHY
CPB
ENZYME INHIBITORS
GUINEA PIGS
HEART
IONS
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
LIGANDS
LIQUID COLUMN CHROMATOGRAPHY
LITHIUM COMPOUNDS
MAGNESIUM COMPOUNDS
MAMMALS
MANGANESE COMPOUNDS
MEMBRANES
METABOLITES
MONOCARBOXYLIC ACIDS
MUSCLES
MYOCARDIUM
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANS
POTASSIUM COMPOUNDS
PROTEINS
RESPONSE MODIFYING FACTORS
RODENTS
SEPARATION PROCESSES
SODIUM COMPOUNDS
TRACER TECHNIQUES
TRANSITION ELEMENT COMPOUNDS
TRITIUM COMPOUNDS
VALENCE
VERTEBRATES