Specific Binding of [3H]LY186126, an Analogue of Indolidan (LY195115), to Cardiac Membranes Enriched in Sarcoplasmic Reticulum Vesicles
作者:
Raymond Kauffman,
Barbara Utterback,
David Robertson,
期刊:
Circulation Research
(OVID Available online 1989)
卷期:
Volume 64,
issue 5
页码: 1037-1040
ISSN:0009-7330
年代: 1989
出版商: OVID
关键词: [3H]LYI86I26;sarcoplasmic reticulum;binding site;indolidan (LY195I15);milrinone
数据来源: OVID
摘要:
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 milri- none. A high-affinity binding site for [3H]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 /nM) produced essentially complete displacement of bound [3H]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 [3H]LY186126 is a useful radioligand for examining the subcellular site(s) responsible for positive inotropic effects of these drugs.
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