Drugs online research references
J Clin Endocrinol Metab. 1986 May;62(5):827-32.
Adrenergic receptors in human liver plasma membranes: predominance of beta 2- and alpha 1-receptor subtypes.
Kawai Y, Powell A, Arinze IJ.
Adrenergic receptors in human liver plasma membranes were characterized by radioligand binding assays. The binding of [3H]dihydroalprenolol [( 3H]DHA) to partially purified membranes was rapid, of high affinity, saturable, and stereospecific. The binding of [125I]iodocyanopindolol to the same membranes was also saturable and stereospecific, but extremely slow, and at 37 C required about 6 h for equilibration. The maximum number of binding sites from six livers determined with these two beta-receptor ligands was 36-83 fmol/mg protein. Catecholaminergic agonists competed for these binding sites in the order typical for beta 2-adrenergic receptors. IPS 339 [(tertiarybutylamino-3-ol-2-propyl)oximino-9-fluorene hydrochloride], a beta 2-selective antagonist, was at least 3 orders of magnitude more potent in inhibiting the binding of [3H]DHA than the beta 1-antagonist, atenolol. Computer-aided analysis of the competition curves as well as Hofstee transformations of the binding data indicated the predominance of the beta 2-subtype. The GTP analog guanyl-5'-yl-imidodiphosphate, decreased the binding affinity of the agonist, l-isoproterenol, indicating the modulation of agonist-promoted coupling of the receptors to guanine nucleotide regulatory proteins. The maximum number of binding sites for the binding of [3H]prazosin and [3H]dihydroergocryptine were the same (60-70 fmol/mg protein), indicating that the majority of the alpha-receptors are of the alpha 1-subtype. Competition experiments with prazosin and yohimbine confirmed the predominance of the alpha 1-receptor subtype, although the presence of alpha 2-receptors cannot be completely ruled out. These results indicate that adrenergic receptors in human liver plasma membranes are predominantly of the beta 2- and alpha 1-subtypes.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=3007555&dopt=Abstract
Br J Pharmacol. 1994 Jun;112(2):493-8.
Effect of salmeterol on human nasal epithelial cell ciliary beating: inhibition of the ciliotoxin, pyocyanin.
Kanthakumar K, Cundell DR, Johnson M, Wills PJ, Taylor GW, Cole PJ, Wilson R.
Department of Thoracic Medicine, Royal Brompton National Heart and Lung Institute, London.
1. Patients with airway infection by Pseudomonas aeruginosa have impaired mucociliary clearance. Pyocyanin is a phenazine pigment produced by P. aeruginosa which is present in the sputum of colonized patients, slows human ciliary beat frequency (CBF) in vitro and slows mucociliary transport in vivo in the guinea-pig. 2. We have investigated the effect of salmeterol, a long-acting beta 2-adrenoceptor agonist, on pyocyanin-induced slowing of human CBF in vitro. Salmeterol (2 x 10(-7) M) was found to reduce pyocycanin (20 micrograms ml-1)-induced slowing of CBF by 53% and the fall in intracellular adenosine 3':5'-cyclic monophosphate (cyclic AMP) by 26% and ATP by 29%. 3. Another beta 2-adrenoceptor agonist, isoprenaline (2 x 10(-7) M), also inhibited pyocyanin-induced slowing of CBF by 39%. 4. The effects of salmeterol (30 min preincubation) persisted after washing the cells. 5. Propranolol (10(-7) M) and the beta 2-specific antagonist, ICI 118551 (10(-6) M) blocked the protective effects of salmeterol completely, but atenolol (10(-6) M) was less effective. These results suggested that the effects of salmeterol on pyocyanin-induced effects were mediated primarily via the stimulation of beta 2-adrenoceptors. 6. Pyocyanin-induced ciliary slowing is associated with a substantial fall in intracellular cyclic AMP and ATP. Salmeterol reversed the effects of pyocyanin on cyclic AMP and ATP. 7. Mucociliary clearance is an important defence mechanism of the airways against bacterial infection. Salmeterol may benefit patients colonized by P. aeruginosa, not only by its bronchodilator action, but also by protecting epithelial cells from pyocyanin-induced slowing of CBF.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7915610&dopt=Abstract
Res Commun Chem Pathol Pharmacol. 1977 Sep;18(1):11-22.
beta-blocking agents and human fat cell adenylate cyclase.
Kather H, Simon B.
The effects of various beta-blocking agents upon the catecholamine-activated adenylate cyclase of human fat cell ghosts were studied. Both non-selective and cardio-selective beta-blocking drugs are capable in inhibiting the human enzyme system. The concentrations of the non-selective beta-blockers (bupranolol, alprenolol, propranolol, 4-hydroxypropranolol, prindolol and oxyprenolol) required to produce half maximal inhibition of isoproterenol-stimulated rates of cAMP-formation were found to be in a narrow range (5X10(-7) M-3X10(-6) M).The cardioselective beta-blocking agents, however, were only 1/100 (methypranol) to 1/1000 (atenolol, practolol) as potent as the non-selective drugs.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=20652&dopt=Abstract
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