Drugs online research references
Br J Pharmacol. 1981 Nov;74(3):547-52.
Demonstration of both beta 1- and beta 2-adrenoceptors mediating relaxation of isolated ring preparations of rat pulmonary artery.
O'Donnell SR, Wanstall JC.
1 Cumulative concentration-response (relaxation) curves to three beta-adrenoceptor agonists, fenoterol (beta 2-selective), isoprenaline (non-selective) and noradrenaline (beta 1-selective) were obtained on isolated ring preparations of rat pulmonary artery contracted with 15 mM KCl. alpha-Adrenoceptors and neuronal and extraneuronal uptakes were blocked with phenoxybenzamine. The agonist concentration-response curves were reproducible. 2 Responses to each of the three agonists could be blocked by the beta-adrenoceptor antagonists atenolol (beta 1-selective) or ICI 118,551 (beta 2-selective) confirming the presence of beta-adrenoceptors. 3 The relative potencies of the agonists were isoprenaline : fenoterol : noradrenaline = 100 : 38 : 1.4. This indicated that the predominant beta-adrenoceptor type was beta 2. 4 Schild plots were obtained for atenolol and ICI 118,551 using the three different agonists. For each antagonist the location of the Schild plot varied depending on which agonist was used. This indicated that the beta-adrenoceptor population mediating relaxation responses to beta-adrenoceptor agonists was not homogeneous. 5 Atenolol was most potent when noradrenaline was the agonist and ICI 118,551 was most potent when fenoterol was the agonist. 6 It is concluded that isolated pulmonary artery ring preparations of the rat contain a mixed population of beta 1- and beta 2-adrenoceptors both mediating relaxation.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=6117344&dopt=Abstract
J Pharm Sci. 1989 Dec;78(12):1035-9.
Liquid chromatographic analysis of atenolol enantiomers in human plasma and urine.
Mehvar R.
College of Pharmacy and Health Sciences, Drake University, Des Moines, IA 50311.
A sensitive, stereospecific high-performance liquid chromatographic assay of atenolol (AT) enantiomers in human plasma and urine was developed. After addition of internal standard (IS, methoxamine) and alkalinization of the plasma, the drug and IS were extracted with ethyl acetate. The organic layer was evaporated and, after addition of saturated sodium carbonate, the residue was derivatized with (-)-menthyl chloroformate at ambient temperature; the reaction was complete within 30 s, with an efficiency of 97.2 +/- 2.6%. The diastereomeric derivatives of AT and IS were then extracted into chloroform and analyzed on a C18 column with a mobile phase consisting of water: acetonitrile: methanol. The samples were detected utilizing a fluorescent detector. Water-diluted urine samples were derivatized directly and then subjected to the same procedure as plasma. Under these conditions, AT diastereomers were separated with a resolution factor of 1.94, free of any interfering peak. An excellent linear relationship (r greater than or equal to 0.998) was obtained between the peak area ratios and the corresponding concentrations in the ranges 12.5-250 and 250-2500 ng/mL for plasma and urine, respectively. The applicability of the method is demonstrated by analysis of plasma and urine concentrations of individual enantiomers of AT after oral administration of a single 100-mg dose to a healthy subject.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2575664&dopt=Abstract
J Hypertens. 1991 Oct;9(10):969-75.
Stress and sodium hypertension in baboons: neuroendocrine and pharmacotherapeutic assessments.
Turkkan JS, Goldstein DS.
Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21205.
Behavioral stress and high dietary salt have been reported to increase blood pressure additively in non-human primates. This study was designed to replicate this phenomenon and to assess neuroendocrine correlates and responses to two commonly used antihypertensives, a beta-adrenoceptor blocker and a thiazide diuretic. High-salt intake (240 mmol sodium per day) and stress were administered for 9 weeks in adult baboons. Oral atenolol hydrochloride (50 mg, twice daily) or hydrochlorothiazide (25 mg/day) was administered for 2 weeks each. In all four baboons, salt loading and stress increased systolic blood pressure (SBP) chronically by 14 mmHg, with increases in water intake, urine osmolality and excretion of sodium, decreases in levels of serum sodium, plasma renin activity and plasma vasopressin and no changes in urinary excretion of norepinephrine or epinephrine. Neither drug decreased SBP during ongoing high salt and stress. The results confirm the additive chronic effects of high-dietary salt intake and behavioral stress on blood pressure in non-human primates. The hypertension in this model is resistant to two antihypertensive drugs commonly used clinically.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1658140&dopt=Abstract
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