Drugs online research references
Circulation. 1977 Aug;56(2):284-8.
The effect of propranolol on canine myocardial CPK distribution space and rate of disappearance.
Cairns JA, Klassen GA.
Canine myocardial CPK was partially purified and injected into 11 conscious mongreal dogs. From serial serum CPK measurements in each dog, mean Kd was calculated as 0.0047 +/- 0.0009 (+/- SD) min-1. Correlation coefficients indicated that CPK disappearance rate was well described by a single exponential expression. Kd measured on consecutive days in four dogs varied minimally. CPK distribution space ranged from 74 to 134% of plasma volume. Propranolol loading with 0.3 mg/kg or 2 mg/kg, followed by hourly maintenance doses, resulted in increased Kd in eight of ten dogs, mean Kd rising from .0048 min-1 to .0059 min-1 (P less than 0.02). Propranolol appeared to increase plasma volume but had no significant effect on the relationship of CPK distribution space to plasma volume. If the serial CPK technique were used to measure infarct size, using an average Kd, propranolol might produce artifactual reduction of infarct size measuremnt by increasing Kd and possibly by increasing plasma volume. The obligation to assess the effect upon CPK Kd and distribution space of an agent designed to limit infarct size is apparent.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=872323&dopt=Abstract
Braz J Med Biol Res. 1995 Nov-Dec;28(11-12):1197-206.
Is the short-term modulation of heart rate in teleost fish physiologically significant? Assessment by spectral analysis techniques.
Altimiras J, Aissaoui A, Tort L.
Departamento de Biologia Cellular i Fisiologia, Universitat Autonoma de Barcelona, Spain.
Heart rate is an important physiological variable in the control of cardiac output, even in fishes, where the importance of stroke volume has been overemphasized. Except for the myxinoids, the fish heart is innervated by cranial nerve X and the nature of this innervation is mainly inhibitory by parasympathetic fibers, although a sympathetic contribution has also been demonstrated. In mammals, cardiac innervation is not only responsible for the control of mean heart rate but it also modulates the beat-to-beat heart rate changes. These beat-to-beat changes are known as heart rate variability (HRV) and appear to be related to fluctuations in respiration and blood pressure. In this paper we demonstrate the link between cardiac innervation and HRV in several species of teleosts because HRV is greatly decreased after vagotomy or atropinization. In contrast, after abolishing the sympathetic influence with propranolol, only slight changes in total HRV are observed, indicating the restricted importance of the adrenergic innervation in determining phasic changes in HRV despite the significant tonic effect which has been demonstrated. Thus, it appears unlikely that the sympathetic influence will be present in any measured spectral component as suggested previously. Furthermore, clear spectral patterns do not always exist and this may be due to the erratic influence of respiration which is clearly faster than heart rate in all fish species studied. This differs from the slow ventilation frequency displayed by many mammalian species that exerts an influence on a beat-to-beat basis (respiratory sinus arrhythmia). Spectral patterns could also be affected by changing levels of circulating catecholamines, although this is still unproved.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8728848&dopt=Abstract
J Pharm Biomed Anal. 1996 Feb;14(4):475-81.
Comparison of two extraction methods for determination of propranolol and furosemide in human plasma by mixed-mode chromatography.
Walshe M, Kelly MT, Smyth MR.
School of Chemical Sciences, Dublin City University, Ireland.
An isocratic high performance liquid chromatographic method is described for the determination of the beta-adrenergic blocking drug, propranolol, and the diuretic, furosemide, in human plasma. The two compounds and the internal standard were extracted from plasma using a two-step extraction technique. Propranolol and pindolol (internal standard) were first extracted from alkaline plasma into diethyl ether; this was followed by extraction of furosemide into acidified ether: hexane (65:35). The two extracts were then combined and evaporated under nitrogen, and the reconstituted residues were analysed on a C18/SCX reversed-phase/cation exchange column with a mobile phase of acetonitrile: 0.1 M sodium acetate pH 4 (33:67). The drugs and the internal standard were detected by UV absorption at 230 nm. The drugs were also extracted from plasma by a column-switching technique utilizing a ten-port valve. The drug compounds were retained on a C18 pre-column. A comparison of RSD for within-batch (intra-assay) and between-batch (inter-assay) runs for both methods was carried out, the liquid/liquid extraction method giving better recovery values. The calibration graphs were linear from 25-300 ng ml-1 for furosemide and 50-400 ng ml-1 for propranolol. Recovery values were > 90.0% by liquid/liquid extraction and > 76.0% by column switching.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8729647&dopt=Abstract
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