Specific binding of (/sup 3/H)LY186126, an analogue of indolidan (LY195115), to cardiac membranes enriched in sarcoplasmic reticulum vesicles

Journal Article · Mon May 01 00:00:00 EDT 1989 · Circ. Res.; (United States)

DOI:https://doi.org/10.1161/01.RES.64.5.1037· OSTI ID:6031237

Kauffman, R F; Utterback, B G; Robertson, D W

LY186126 was found to be a potent inhibitor of type IV cyclic AMP phosphodiesterase located in the sarcoplasmic reticulum of canine cardiac muscle. This compound, a close structural analogue of indolidan (LY195115), was prepared in high specific activity, tritiated form to study the positive inotropic receptor(s) for cardiotonic phosphodiesterase inhibitors such as indolidan and milrinone. A high-affinity binding site for (/sup 3/H)LY186126 was observed (Kd = 4 nM) in purified preparations of canine cardiac sarcoplasmic reticulum vesicles. Binding was proportional to vesicle protein, was inactivated by subjecting membranes to proteolysis or boiling, and was dependent on added Mg2+. Scatchard analysis suggested the presence of a single class of binding sites in the membrane preparation. Indolidan, milrinone, and LY186126 (all at 1 microM) produced essentially complete displacement of bound (/sup 3/H)LY186126, while nifedipine, propranolol, and prazosin had little or no effect at this concentration. This represents the first reported use of a radioactive analogue to label the inotropic receptor for cardiotonic phosphodiesterase inhibitors. The results suggest that (/sup 3/H)LY186126 is a useful radioligand for examining the subcellular site(s) responsible for positive inotropic effects of these drugs.

• Research Organization: Eli Lilly and Co., Indianapolis, IN (USA)
• OSTI ID: 6031237
• Journal Information: Circ. Res.; (United States), Vol. 64:5
• Country of Publication: United States
• Language: English

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59 BASIC BIOLOGICAL SCIENCES
ENZYME INHIBITORS
RECEPTORS
BIOCHEMICAL REACTION KINETICS
CELL MEMBRANES
DOGS
INDOLES
LIGANDS
MICROSOMES
MYOCARDIUM
PHOSPHODIESTERASES
PYRIDAZINES
TRACER TECHNIQUES
TRITIUM COMPOUNDS
ANIMALS
AROMATICS
AZAARENES
AZINES
AZOLES
BODY
CARDIOVASCULAR SYSTEM
CELL CONSTITUENTS
ENZYMES
ESTERASES
HEART
HETEROCYCLIC COMPOUNDS
HYDROLASES
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
MAMMALS
MEMBRANE PROTEINS
MEMBRANES
MUSCLES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANOIDS
ORGANS
PROTEINS
PYRROLES
REACTION KINETICS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques