ft-Receptors constitute only 10-30% of the total 0-adrenergic receptors in mammalian ventricular myocardium, but their precise tissue location cannot be determined easily by measuring physiological variables. To delineate the distribution of /3-receptor subtypes in myocytic and vascular components of the heart, we incubated transmural sections of canine left ventricle with [Iodo]cyanopindolol a...

Rat isolated right atria obtained 1 wk after sinoaortic denervation were less sensitive to the chronotropic actions of beta-agonists than were tissues obtained from animals that underwent sham surgery or no surgery at all. The potencies, but not the maximal responses for two high efficacy agonists, norepinephrine and isoproterenol, were reduced about 3- to 4-fold. Sino-aortic denervation (SAD) ...

The goal of this study was to determine the mechanism of ,/-adrenergic receptor desensitization after chronic elevation of circulating NE levels. Osmotic minipumps containing either NE or saline were implanted subcutaneously in dogs for 34 wk. Physiologic desensitization to isoproterenol was confirmed in conscious dogs, i.e., left ventricular dP/dt increased in response to isoproterenol (0.4 ug...

The distribution of j3-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 ,B-adrenergic receptors. Binding of the radioligand to sections of the three coronary arteries under study ...

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...

This rapid, sensitive, simple radioreceptor assay (RRA) for l-propranolol and its active metabolites in unextracted samples requires 5 microL of sample, a beta-adrenergic antagonist, 125-l-labeled (-)cyanopindolol (125ICYP), and turkey erythrocyte membrane receptors (Kd = 40 pmol/L). Equal volumes (100 microL) of diluted sample and 125ICYP are incubated with 500 microL of erythrocyte membranes ...

The density of f-adrenergic receptors is reduced in crude membranes prepared from failing human myocardium. We used quantitative autoradiography of radioligand binding sites in intact tissue slices to determine whether the total tissue content of receptors is reduced and to characterize the transmural distribution of receptors in cardiac myocytes and the coronary vasculature in hearts obtained ...