A fundamental question regarding receptor-G protein interaction is whether different agonists can lead a receptor to different intracellular signaling pathways. Our previous studies have demonstrated that although most beta(2)-adrenoceptor agonists activate both G(s) and G(i) proteins, fenoterol, a full agonist of beta(2)-adrenoceptor, selectively activates G(s) protein. Fenoterol contains two ...

Sustained stimulation of the b -adrenoceptor leads to a desensitization of the receptor-mediated adenylyl cyclase stimulation. While 2 desensitization promoted by nanomolar concentrations of isoproterenol involves the phosphorylation of the b -adrenoceptor by protein 2 kinase A alone, both protein kinase Aand b-adrenoceptor kinase-mediated phosphorylation leading to the binding of b-arrestin co...

Regional variations in adipocyte lipolysis between subcutaneous and visceral fat may be important for obesity complications. In the present study, we compared adrenergic regulation of lipolysis in omental and subcutaneous adipocytes from obese (n = 15) and non-obese (n = 14) male subjects. Waist-to-hip ratio, blood pressure, plasma insulin, and plasma triglycerides were increased in obesity. No...

It has been suggested that there is a link between epinephrine synthesis and the development of β2-adrenoceptor-mediated effects, but it remains to be determined whether this development is triggered by epinephrine. The aim of this study was to characterize β-adrenoceptor-mediated relaxation and facilitation of norepinephrine release in the aorta of phenylethanolamine-N-methyltransferase-knocko...

It has been suggested that there is a link between epinephrine synthesis and the development of b2-adrenoceptor–mediated effects, but it remains to be determined whether this development is triggered by epinephrine. The aim of this study was to characterize b-adrenoceptor–mediated relaxation and facilitation of norepinephrine release in the aorta of phenylethanolamine-Nmethyltransferase–knockou...

OBJECTIVE Our investigation was designed to examine the signaling pathway involved in the enhancement of vascular endothelial growth factor (VEGF) release by β-adrenoceptor agonists. MATERIALS AND METHODS Human U937 cells differentiated into macrophages were primed with lipopolysaccharide (LPS) in the absence or presence of β-adrenoceptor agonists and antagonists. The VEGF released and the in...

β3-Adrenoceptor agonists have recently been introduced for the treatment of overactive urinary bladder syndrome. Their target, the β3-adrenoceptor, was discovered much later than β1- and β2-adrenoceptors and exhibits unique properties which make extrapolation of findings from the other two subtypes difficult and the β3-adrenoceptor a less-understood subtype. This article discusses three aspects...

It has been reported that trypan blue, a diazo dye with polyamphipathic structure, can inhibit the coupling of receptors to G-proteins. The present study was carried out to investigate the effect of trypan blue on the actions of adrenoceptor agonists in the guinea-pig atrium. Trypan blue (10 and 100 microM) antagonized the positive inotropic effects of isoprenaline and dobutamine by shifting th...

Cold allodynia is an important distinctive feature of neuropathic pain. The present study examined whether single or repetitive treatment of diluted bee venom (DBV) reduced cold allodynia in sciatic nerve chronic constriction injury (CCI) rats and whether these effects were mediated by spinal adrenergic receptors. Single injection of DBV (0.25 or 2.5 mg/kg) was performed into Zusanli acupoint 2...

beta-Adrenergic agonists are potent relaxing agents of airway smooth muscle; however, they are often incapable of fully reversing agonist-mediated contractions. The present study was designed to quantitate the relationship between beta-adrenoceptor binding, signal transduction, and relaxation in rabbit tracheal smooth muscle (TSM). TSM segments contracted with acetylcholine to 25 to 75% maximal...