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 04:00:00 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), Journal Name: Circ. Res.; (United States) Vol. 64:5; ISSN CIRUA
• Country of Publication: United States
• Language: English

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