The distribution of beta-adrenergic receptors in sections of the human right and left coronary arteries and of the anterior intraventricular branch was studied by the use of combined in vitro radioreceptor binding and autoradiographic techniques. [125I]Cyanopindolol was used as a ligand for beta-adrenergic receptors. Binding of the radioligand to sections of the three coronary arteries under st...

Intracellular recordings were made from presumed dopamine-containing neurons in slices cut from the midbrain of the rat. Focal electrical stimulation produced a hyperpolarizing synaptic potential that was reduced by 75-95% by the GABAB-receptor antagonist 2-hydroxysaclofen (300 microM). 5-HT (3-100 microM) reduced the amplitude of the GABAB synaptic potential by 20-74%, with a 50% reduction at ...

To assess whether internalization of beta-adrenergic receptor occurs in the CNS, we have isolated clathrin-coated vesicles from bovine forebrain and examined them for the presence of beta-adrenergic receptor binding and adenylate cyclase activities. A coated vesicle enriched preparation isolated by successive D2O-Ficoll density gradient centrifugations was applied to a glass bead permeation col...

Structural studies of mammalian membrane proteins, such as transporters and G protein-coupled receptors, are hampered by their lack of stability in detergents. This is manifested by a loss of activity during purification, often accompanied by aggregation, even when mild detergents such as dodecylmaltoside (DDM) are used. The situation is exacerbated during the final stages of purification, wher...

beta 2-Receptors constitute only 10-30% of the total beta-adrenergic receptors in mammalian ventricular myocardium, but their precise tissue location cannot be determined easily by measuring physiological variables. To delineate the distribution of beta-receptor subtypes in myocytic and vascular components of the heart, we incubated transmural sections of canine left ventricle with [125Iodo]cya...

Peripheral vasodilator responsiveness was examined in pacing-induced heart failure (HF) in 11 conscious dogs chronically instrumented for measurement of systemic (total peripheral resistance [TPR]) and local (iliac blood flow) vascular resistance. Dose responses to isoproterenol (ISO), acetylcholine (ACh), and nitroglycerin (NTG) were examined in the same dogs before pacing (control) and after ...

Denervation supersensitivity was demonstrated in anesthetized dogs 5 to 10 days after transmural myocardial infarction produced by latex embolization of a diagonal branch of the left anterior descending coronary artery. Sympathetic efferent denervation in noninfarcted myocardium apical to the infarction was demonstrated by a 90% depletion of myocardial norepinephrine content in the apical (45 +...

Tocolytic therapy with beta-adrenergic receptor agonists is a standard regimen to prevent preterm birth. Agonists exposure of beta-adrenergic receptors causes receptor desensitization in other organs, and this may limit the therapeutic value of beta-adrenergic receptor agonists. To study the effects of prolonged beta-adrenergic agonist treatment in human myometrium, we obtained biopsies during ...

BACKGROUND Heart failure is associated with activation of the sympathetic nervous system and downregulation of beta-receptors. However, the coupling between cardiac sympathetic neuronal function and the beta-receptor during the development of hypertensive heart failure is not clear. METHODS AND RESULTS We determined cardiac neuronal function and beta-receptors with a dual-tracer method of [13...

The distribution of adrenergic receptors in specific components of the heart such as vessels and myocytes cannot be determined easily with assays of membranes prepared from homogenates of whole tissue. Accordingly, we characterized the binding of the potent nonsubtype selective antagonist [125iodo]cyanopindolol to beta-receptors in unfixed transmural slices of feline and canine left ventricle. ...