METHODS. Isolated arteries from the intraocular part of the porcine ciliary artery were suspended in microvascular myographs for isometric tension recording. The segments were contracted with the a2-adrenoceptor agonists brimonidine, apraclonidine, and oxymetazoline. To determine which subtypes of the a2-adrenoceptor mediate this contraction, antagonists subselective for the different a2-adreno...

The alpha1-adrenergic agonist phenylephrine stimulated phospholipase D (PLD) activity in Rat 1 fibroblasts transfected to express either the wild-type hamster alpha1B-adrenoceptor or a constitutively active mutant (CAM) form of this receptor. The EC50 for agonist stimulation of PLD activity was substantially lower at the CAM receptor than at the wild-type receptor as previously noted for phenyl...

Chronic visceral pain in patients with irritable bowel syndrome (IBS) has been difficult to treat effectively partially because its pathophysiology is not fully understood. Recent studies show that norepinephrine (NE) plays an important role in the development of visceral hypersensitivity. In this study, we designed to investigate the role of adrenergic signaling in visceral hypersensitivity in...

-Adrenoceptors contribute to hypertension in spite of the fact that -adrenoceptor agonists lower blood pressure. We aimed to differentiate between these functions and to identify differences between spontaneously hypertensive and normotensive rats. -Adrenoceptor antagonists with different subtype selectivity or the ability to cross the blood-brain barrier were used to demonstrate -adrenoceptor ...

BACKGROUND Propofol may decrease myocardial contractility via actions on the beta-adrenoceptor-mediated signal transduction. The aim of this study was to evaluate the effect of propofol via beta-adrenoceptor-mediated signal transduction by measuring the tissue levels of cAMP (cyclic adenosine monophosphate). METHODS The effects of propofol on beta-adrenoceptor mediated cascades were measured ...

Rhinovirus (RV) infections account for approximately two thirds of all virus-induced asthma exacerbations and often result in an impaired response to β2 agonist therapy. Using an in vitro model of RV infection, we investigated the mechanisms underlying RV-induced β2 adrenoceptor desensitization in primary human airway smooth muscle cells (ASMC). RV infection of primary human bronchial epithelia...

Many G-protein-coupled receptors, including the alpha(1b)-adrenoceptor, form homo-dimers or oligomers. Mutation of hydrophobic residues in transmembrane domains I and IV alters the organization of the alpha(1b)-adrenoceptor oligomer, with transmembrane domain IV playing a critical role. These mutations also result in endoplasmic reticulum trapping of the receptor. Following stable expression of...

1. Noradrenaline stimulates gluconeogenesis through an (a-adrenoceptor in renal cortical tubule fragments from fed rats incubated with 5 mM-lactate. 2. The selective a1-adrenoreceptor agonist methoxamine stimulated gluconeogenesis, but the selective a2-adrenoceptor agonist clonidine was ineffective. 3. The selective a1-adrenoceptor antagonist thymoxamine blocked the stimulatory effects on gluco...

alpha2C adrenoceptors occur in high density in the striatum, but the functional role of these receptors is uncertain. Mice with targeted inactivation of the alpha2C adrenoceptor gene (Adra2c-/-) and genetically related control mice expressing the wild-type alpha2C adrenoceptor (Adra2c+/+) were used to determine whether striatal alpha2C adrenoceptors modulate adenylyl cyclase activation. In stri...

The important regulator of cardiac function, cAMP, is hydrolyzed by different cyclic nucleotide phosphodiesterases (PDEs), whose expression and activity are not uniform throughout the heart. Of these enzymes, PDE2 shapes β1 adrenoceptor-dependent cardiac cAMP signaling, both in the right and left ventricular myocardium, but its role in regulating β2 adrenoceptor-mediated responses is less well ...