Drugs online research references
Pharmacol Biochem Behav. 1992 Aug;42(4):791-6.
Pharmacological mechanisms in the cardiovascular effects of methamphetamine in conscious squirrel monkeys.
Schindler CW, Zheng JW, Tella SR, Goldberg SR.
Behavioral Pharmacology and Genetics Laboratory, NIDA Addiction Research Center, Baltimore, MD 21224.
The effects of methamphetamine were studied on cardiovascular function in conscious squirrel monkeys. Methamphetamine (0.1-3.0 mg/kg, IV) produced a dose-dependent increase in blood pressure. Its effects on heart rate were more complex, with lower doses (0.1-0.3 mg/kg) producing increases in heart rate and higher doses (1.0-3.0 mg/kg) producing decreases. To determine the pharmacological mechanisms involved in methamphetamine's effects, a number of drugs were tested as pretreatments to an injection of 0.2 mg/kg methamphetamine. This dose produced the maximal heart rate increase. The alpha 1-antagonist prazosin completely antagonized the effects of methamphetamine on blood pressure, while the nonselective beta-antagonist propranolol and beta 1-selective antagonist atenolol completely antagonized the tachycardiac effect of methamphetamine. The dopaminergic antagonists SCH 23390 and haloperidol antagonized some of the cardiovascular effects of methamphetamine. These results indicate that the pressor and tachycardiac effects of methamphetamine are mediated via alpha 1- and beta 1-adrenoceptor mechanisms, respectively. Dopaminergic mechanisms are also involved in methamphetamine's cardiovascular effects.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1325059&dopt=Abstract
Tidsskr Nor Laegeforen. 1992 Jun 30;112(17):2235-6.
[Treatment of hypertension in the elderly--diuretics/atenolol?]
[Article in Norwegian]
Osnes JB.
Farmakologisk institutt Universitetet i Oslo.
The recently published MRC-trial on treatment of hypertension in older adults showed generally beneficial effects. Significantly lower rates of coronary events and cardiovascular events/deaths were found in the diuretic group than in the atenolol group. Special circumstances and weak points in the study it self do not seem to have caused artificial differences between the two treatment groups. Thus the comparison seems to be justified and the demonstrated differences are regarded as real. This study fits into the pattern of other trials. The diuretic regimen with a potassium-magnesium-saving component may have been of importance. Whether the trial reflects a general beta-blocker effect in older adults with hypertension or a more specific atenolol effect is not clarified.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1523667&dopt=Abstract
J Clin Invest. 1991 Apr;87(4):1153-7.
Effect of isoproterenol on intracellular pH of the intercalated cells in the rabbit cortical collecting ducts.
Hayashi M, Yamaji Y, Iyori M, Kitajima W, Saruta T.
Department of Internal Medicine, School of Medicine, Keio University, Tokyo, Japan.
To examine the mechanisms which regulate the functions of the intercalated cells (ICs) in the cortical collecting duct (CCD), the effect of isoproterenol on intracellular pH (pHi) of ICs was studied with the in vitro microperfused rabbit CCD, using the single cell pHi determination technique with fluorescent dye, 2',7'-bis-(2-carboxyethyl)-5(and-6)carboxyfluorescein. The pHi of beta-IC was significantly decreased with the addition of basolateral 10(-6) M isoproterenol (7.21 +/- 0.04 to 7.05 +/- 0.04), whereas alpha-IC did not show any change. This response of beta-IC to isoproterenol was dose-dependent and completely inhibited by the beta-blockers, atenolol or propranolol. The addition of forskolin or 8-Br-cAMP mimicked the effects of isoproterenol, suggesting that the activation of adenylate cyclase induced the decrease in pHi. The rate of pHi changes after the Cl- removal from the perfusate, which is considered to reflect the activity of luminal anion exchanger, was significantly higher with isoproterenol (0.032 +/- 0.009 pH unit/s) than that in the control (0.023 +/- 0.009 pH unit/s). The present studies provide direct evidence for the regulation of beta-IC function by beta-adrenergic receptor; and the luminal Cl-/HCO3- exchanger was considered to be stimulated by beta-agonist, directly.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1849143&dopt=Abstract
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