Isoproterenol, norepinephrine, and epinephrine covalently bound to glass beads exert a positive inotropic effect on isometrically contracting papillary muscles from cats. Immobilized isoproterenol maintains increases in force and velocity of contraction for more than 5 hr. 1 muM Cocaine potentiates the action of immobilized norepinephrine, isoproterenol, and epinephrine, but not of isoproterenol in solution. The data presented indicate that the effects of immobilized catecholamines are not due to their coming off the glass. The effects observed with cocaine and immobilized catecholamines are not altered by prior treatment of the muscle with reserpine. These results suggest that the major site of catecholamine action is on receptors located on the extended surface of myocardial cells and a post-junctional site for cocaine potentiation.

Animals↗

PubMed1972

Biologically active catecholamines covalentyly bound to glass beads.

Catecholamines bound covalently to glass beads have been found to have biological activity in several systems. Experimental evidence has been found that immobilized epinephrine and isoproterenol accelerate the heart rate in dogs, chick embryo, and chick heart cells grown in culture, whereas immobilized propranolol results in a decrease in heart rate. Isoproterenol bound to glass beads has also been shown to markedly increase the level of adenosine 3':5'-cyclic monophosphoric acid in glial cells. The effects of the immobilized catecholamines are of longer duration than when the compounds are administered in solution. The present data indicate that the compounds are exerting their action when bound to the beads.

Animals↗

PubMedDate not supplied

Genome sequence analysis: scientific objectives and practical strategies.

Explore the source record for details and available documents.

Human Genome Project↗

PubMedDate not supplied

Beta-adrenergic receptor structure, synthesis, antibodies and human disease.

Lung beta 2-adrenergic receptors have been isolated using a covalent affinity label and monoclonal and autoantibodies with specificity toward the receptor. The beta 2-receptor monomer has a molecular mass of 58-64,000 daltons. Target size analysis indicates that the beta 2-receptor exists as a dimer in lung membranes. The half life of the beta 2-receptor on cultured lung cells is on the order of 20-30 h. Glucocorticoids induce the synthesis of beta 2-receptors, resulting in a doubling of the membrane concentration of receptors in 24 h. Autoantibodies to beta 2-adrenergic receptors may play a role in beta 2-receptor associated human diseases including asthma. Autoantibodies to beta 2-receptors in humans are associated with decreased sensitivity of beta 2-receptor functions and increased responsiveness of alpha-adrenergic and muscarinic cholinergic receptors.

Animals↗