Adenylate cyclase regulation in intact cultured myocardial cells
To examine the coupling of cardiac cell-surface ..beta..-adrenergic receptors to adenylate cyclase activation and contractile response, the authors studied this receptor-effector response system in monolayers of spontaneously contracting chick embryo ventricular cells under physiological conditions. The hydrophilic ligand /sup 3/H-CGP12177 identified uniformly high-agonist affinity ..beta..-adrenergic receptors. Isoproterenol-stimulated cyclic AMP (cAMP) accumulation with 50% effective concentration at (EC/sub 50/) = 12.1 nM and augmented contractile response with EC/sub 50/ = 6 nM under identical conditions. One micromolar isoproterenol induced receptor loss from the cell surface with t/sub 1/2/ = 13.2 min; under identical conditions cAMP content declined with t/sub 1/2/ = 13.5 min and contractile response with t/sub 1/2/ = 20.7 min. After agonist removal cAMP response recovered with t/sub 1/2/ = 15.7 min and receptors with t/sub 1/2/ = 24.7 min. Sixty minutes after agonist removal there was recovery of 52% of maximal cAMP responsiveness and 82% of the initial number of receptors; receptor occupancy was associated with 78% of initial contractile response. Agonist affinity for cell-surface receptors was changed only modestly by agonist exposure. They conclude that for this system there is relatively close coupling between high-affinity receptors, adenylate cyclase stimulation, and contractile response.
- Research Organization:
- Brigham and Women's Hospital, Boston, MA
- OSTI ID:
- 6219721
- Journal Information:
- Am. J. Physiol.; (United States), Journal Name: Am. J. Physiol.; (United States) Vol. 252:1; ISSN AJPHA
- Country of Publication:
- United States
- Language:
- English
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550601* -- Medicine-- Unsealed Radionuclides in Diagnostics
59 BASIC BIOLOGICAL SCIENCES
62 RADIOLOGY AND NUCLEAR MEDICINE
AMP
ANIMAL CELLS
ANIMALS
AUTONOMIC NERVOUS SYSTEM AGENTS
BIOCHEMICAL REACTION KINETICS
BIOCHEMISTRY
BIRDS
BODY
CARDIOVASCULAR SYSTEM
CHEMISTRY
CHICKENS
CYCLASES
DRUGS
EMBRYONIC CELLS
ENZYMES
FOWL
HEART
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
LIGANDS
LYASES
MEMBRANE PROTEINS
MUSCLES
MYOCARDIUM
NUCLEOTIDES
ORGANIC COMPOUNDS
ORGANS
PHYSIOLOGY
PROTEINS
RADIORECEPTOR ASSAY
REACTION KINETICS
RECEPTORS
SYMPATHOMIMETICS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
VERTEBRATES