Recent experiments to derive a thermally stable mutant of turkey beta-1-adrenergic receptor (beta1AR) have shown that a combination of six single point mutations resulted in a 20 degrees C increase in thermal stability in mutant beta1AR. Here we have used the all-atom force-field energy function to calculate a stability score to detect stabilizing point mutations in G-protein coupled receptors....

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 [iodo]cyanopindolol to /3-receptors in unfixed transmural slices of feline and canine left ventricle. Speci...

Little is currently known regarding the electrophysiological response elicited by 5-hydroxytryptamine-7 (5-HT(7)) receptor stimulation in the brain. Previous anatomical studies have shown that the anterior thalamus expresses a high density of 5-HT7 receptors. Therefore, we used whole-cell recording techniques in the in vitro brain slices to examine the effects of serotonin on neurons of the ant...

Chronic stress elevates plasma norepinephrine, which enhances expression of the α(1C)-subunit of Ca(v)1.2b channels in colonic smooth muscle cells within 1 h. Transcriptional upregulation usually does not explain such rapid protein synthesis. We investigated whether chronic stress-induced release of norepinephrine utilizes posttranscriptional mechanisms to enhance the α(1C)-subunit. We performe...

The mechanisms underlying the blunted contractile response to -adrenergic receptor ( -AR) stimulation in heart failure (HF) are incompletely understood, especially with regard to -AR subtype–specific regulation of L-type Ca channels. We evaluated the impact of HF induced by pacing tachycardia on -AR regulation of L-type Ca channels in a canine model. To evaluate changes in the relative subcellu...

The β1-adrenoceptor (β1AR) is a G protein-coupled receptor (GPCR) that is activated by the endogenous agonists adrenaline and noradrenaline. We have determined the structure of an ultra-thermostable β1AR mutant bound to the weak partial agonist cyanopindolol to 2.1 Å resolution. High-quality crystals (100 μm plates) were grown in lipidic cubic phase without the assistance of a T4 lysozyme or BR...

Prediction of 3D structures of membrane proteins, and of G-protein coupled receptors (GPCRs) in particular, is motivated by their importance in biological systems and the difficulties associated with experimental structure determination. In the present study, a novel method for the prediction of 3D structures of the membrane-embedded region of helical membrane proteins is presented. A large poo...

Background—Heart failure is associated with activation of the sympathetic nervous system and downregulation of b-receptors. However, the coupling between cardiac sympathetic neuronal function and the b-receptor during the development of hypertensive heart failure is not clear. Methods and Results—We determined cardiac neuronal function and b-receptors with a dual-tracer method of [I]metaiodoben...

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 ...

Here, we describe the preclinical pharmacological profile of 5-[(R)-2-(5,6-diethyl-indan-2-ylamino)-1-hydroxy-ethyl]-8hydroxy-1H-quinolin-2-one (indacaterol), a novel, chirally pure inhaled 2 adrenoceptor agonist, in comparison with marketed drugs. Indacaterol is close to a full agonist at the human 2 adrenoceptor (Emax 73 1% of the maximal effect of isoprenaline; pEC50 8.06 0.02), whereas salm...