We have used two different cultured cell lines—S49 lymphoma cells and BC3H-1 muscle cells— to examine the regulation of /3-adrenergic receptors by receptor antagonists. Rather than an increase ("up-regulation") of receptor number that such antagonists often produce, we found that certain /3-blockers elicit a decrease ("down-regulation") of beta-adrenergic receptors. Alprenolol and propranolol, ...

Scheiderer, Cary L., Lynn E. Dobrunz, and Lori L. McMahon. Novel form of long-term synaptic depression in rat hippocampus induced by activation of 1 adrenergic receptors. J Neurophysiol 91: 1071–1077, 2004. First published October 22, 2003; 10.1152/jn.00420.2003. Neurons located in the locus coeruleus project to hippocampus and provide noradrenergic innervation necessary for hippocampal-depende...

Recently, vast studies have been focused on the antinociceptive and anesthetic effects of α2 adrenergic receptors, using specific drugs such as medetomidine and dexmedetomidine. In the present study, we tried to assess the peripheral and central effects of dexmedetomidine in phasic and tonic pain, on rats, using tail flick and formalin tests. Dexmedetomidine, administered intraperitoneally (25,...

We have used wild-type and variants of the T-lymphoma cell line S49 to explore internalization and down-regulation of adenylate cyclase-linked beta-adrenergic receptors. Internalization was defined by the loss in "surface receptors" detected at 4 degrees C on intact cells by the antagonists [3H]CGP-12177 or [125I]iodocyanopindolol, whereas down-regulation was defined as the loss in total cellul...

In the isolated perfused hindlimb preparation of the dog, pressor responses to norepinephrine (NE) are mediated by postsynaptic alpha 1- and alpha 2-adrenergic receptors. Results obtained using preferential alpha 1- and alpha 2-adrenergic receptor antagonists suggest that the alpha 1-subtype is predominantly innervated while both alpha 1- and alpha 2-adrenergic receptor subtypes in vascular smo...

To determine the site and possible mechanism of action of adrenergic agents in regulating intraocular pressure, experiments were undertaken to identify, localize, and characterize beta-adrenergic receptors associated with adenylate cyclase in various ocular tissues involved in secretion and reabsorption of aqueous humor. The ciliary process epithelium was found to be enriched in an adenylate cy...

Signals mediated by G-protein-linked receptors display agonist-induced attenuation and recovery involving both protein kinases and phosphatases. The role of protein kinases and phosphatases in agonist-induced attenuation and recovery of beta-adrenergic receptors was explored by two complementary approaches, antisense RNA suppression and co-immunoprecipitation of target elements. Protein phospha...

We describe the cloning and functional expression of a cDNA encoding a novel G protein-coupled receptor, which was isolated from the central nervous system of the pond snail Lymnaea stagnalis. The amino acid sequence predicted by this cDNA shows highest similarity with the sequence of the Locusta tyramine receptor, the Drosophila tyramine/octopamine receptor, and the mammalian alpha-adrenergic ...

The pharmacodynamic activities of two beta adrenergic antagonists, propranolol and practolol, were compared in eight hypertensive patients. The activity of each antagonist was established in relation to its blood concentration at maximal and submaximal adrenergic blockade defined by inhibition of exercise tachycardia. Maximal inhibition of exercise tachycardia was comparable with both drugs and...

Beta-adrenergic drugs affect lens epithelial and fiber cells. The regulation and cellular integration of lens beta-adrenergic responses are largely unknown. These studies further characterize beta-adrenergic receptors in lens cells with respect to cyclic adenosine monophosphate (cAMP) production and identification of receptor polypeptides. Stimulation of beta-adrenergic receptors in organ-cultu...