Drugs online research references
Proc Natl Acad Sci U S A. 1993 Feb 15;90(4):1541-5.
Human immunodeficiency virus coat protein gp120 inhibits the beta-adrenergic regulation of astroglial and microglial functions.
Levi G, Patrizio M, Bernardo A, Petrucci TC, Agresti C.
Laboratory of Pathophysiology, Istituto Superiore di Sanita, Rome, Italy.
The goal of our study was to assess whether the human immunodeficiency virus (HIV) coat protein gp120 induces functional alterations in astrocytes and microglia, known for their reactivity and involvement in most types of brain pathology. We hypothesized that gp120-induced anomalies in glial functions, if present, might be mediated by changes in the levels of intracellular messengers important for signal transduction, such as cAMP. Acute (10 min) exposure of cultured rat cortical astrocytes or microglia to 100 pM gp120 caused only a modest (50-60%), though statistically significant, elevation in cAMP levels, which was antagonized by the beta-adrenergic receptor antagonist propranolol. More importantly, the protein substantially depressed [by 30% (astrocytes) and 50% (microglia)] the large increase in cAMP induced by the beta-adrenergic agonist isoproterenol (10 nM), without affecting that induced by direct adenylate cyclase stimulation by forskolin. Qualitatively similar results were obtained using a glial fibrillary acidic protein (GFAP)-positive human glioma cell line. The depression of the beta-adrenergic response had functional consequences in both astrocytes and microglia. In astrocytes we studied the phosphorylation of the two major cytoskeletal proteins, vimentin and GFAP, which is normally stimulated by isoproterenol, and found that gp120 partially (40-50%) prevented such stimulation. In microglial cells, which are the major producers of inflammatory cytokines within the brain, gp120 partially antagonized the negative beta-adrenergic modulation of lipopolysaccharide (10 ng/ml)-induced production of tumor necrosis factor alpha. Our results suggest that, by interfering with the beta-adrenergic regulation of astrocytes and microglia, gp120 may alter astroglial "reactivity" and upset the delicate cytokine network responsible for the defense against viral and opportunistic infections.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8381971&dopt=Abstract
J Pharmacol Exp Ther. 1993 Feb;264(2):879-88.
Alpha-2 adrenergic receptors in inner medullary collecting duct cells of the rabbit kidney.
Clarke D, Garg LC.
Department of Pharmacology and Therapeutics, University of Florida College of Medicine, Gainesville.
The stimulation of alpha-2 adrenergic receptors in the kidney produces diuresis. In this study, alpha-2 adrenergic receptors were examined in inner medullary collecting duct (IMCD) cells isolated from the rabbit kidney. The equilibrium binding of [3H] rauwolscine to IMCD cell homogenate was measured after incubation for 45 min at 25 degrees C in the absence (total binding) and presence (nonspecific binding) of 100 microM phentolamine. The specific binding of [3H]rauwolscine was saturable with a Bmax of 170 fmol/mg of protein and Kd of 4.18 nM. The displacement of [3H]rauwolscine binding to IMCD cells by adrenergic antagonists and agonists displayed the following order of potency: phentolamine > yohimbine > clonidine > oxymetazoline > azepexole > propranolol > prazosin > alpha-methyl norepinephrine > epinephrine. Activation of alpha-2 adrenergic receptors by azepexole decreased vasopressin- and forskolin-stimulated cAMP formation in the IMCD cells. Because IMCD cells in the kidney have a hypertonic environment made up of urea and NaCl, we also determined the effects of a mixture of NaCl and urea (1200 mOsm/kg water) on the binding of [3H]rauwolscine and cAMP formation in the IMCD cells. The hypertonicity increased the Kd and Bmax of [3H]rauwolscine binding to 15.2 nM and 240 fmol/mg of protein, respectively. In addition, hypertonicity decreased forskolin-stimulated cAMP formation in IMCD cells. It is concluded that: 1) high-affinity specific alpha-2 adrenergic receptors are present in the rabbit IMCD; 2) selective alpha-2 agonists inhibit vasopressin- and forskolin-stimulated cAMP formation in rabbit IMCD and 3) the effects of adrenergic drugs on the IMCD in vivo will depend on the renal medullary osmolality that itself depends on the state of the hydration of the animal.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8382282&dopt=Abstract
Br J Pharmacol. 1993 Feb;108(2):484-9.
The affinity of betaxolol, a beta 1-adrenoceptor-selective blocking agent, for beta-adrenoceptors in the bovine trachea and heart.
Satoh E, Narimatsu A, Hosohata Y, Tsuchihashi H, Nagatomo T.
Pharmaceuticals Laboratory, Research Center, Mitsubishi Kasei Corporation, Yokohama, Japan.
1. The specificity of betaxolol, a beta-adrenoceptor antagonist, for beta 1- and beta 2-adrenoceptors was compared with that of other beta-antagonists, atenolol, ICI-118551, butoxamine and (+/-)-propranolol, in the bovine trachea and heart by competitive interaction with [3H]-CGP12177 as a radioligand. 2. The radioligand Kd values were 0.75 +/- 0.12 and 1.60 +/- 0.11 nM in the trachea and heart, respectively, and the Bmax values were 34.00 +/- 4.41 and 21.54 +/- 2.94 fmol mg-1 protein, respectively. 3. Using ICI-118551, we determined the ratio of beta 1:beta 2-adrenoceptors in the trachea and heart to be approximately 29:71 and 56:44, respectively. 4. In the trachea, a beta 2-predominant tissue, betaxolol and atenolol were more selective for beta 1-adrenoceptor binding sites than beta 2-adrenoceptor binding sites, whereas ICI-118551 and butoxamine were more selective for beta 2-adrenoceptor binding sites. 5. The beta 1-selectivity of betaxolol was 2.2 and 2.7 fold higher than that of atenolol in the bovine trachea and heart. These findings suggest that betaxolol may be useful in the treatment of hypertension, cardiac arrhythmia and angina pectoris.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8383566&dopt=Abstract
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