Heterochronic changes in parameters of cardiac pumping function in rat pups

Cardiac pumping function was studied in rat pups by thoracic tetrapolar rheography. The mean daily increment in blood stroke volume increased with age, while the mean daily changes in HR decreased starting from day 30 of life. Changes in the parameters of minute volume of circulation to a greater extent depended on stroke volume than on HR. © Springer Science+Business Media, Inc. 2006

Voltammetric determination of papaverine and drotaverine

Isoquinoline derivatives (papaverine and drotaverine) are oxidized at a graphite electrode in a 0.1 M sulfuric acid solution to give voltammetric waves at 1.1 V for papaverine and at 1.05 and 1.28 V for drotaverine. Determination limits and linearity ranges of currents as functions of papaverine and drotaverine concentrations are estimated. Microgram amounts of papaverine and drotaverine are determined in model solutions (RSD = 1-4%). A procedure for the direct determination of papaverine and drotaverine in pharmaceuticals is proposed. © 2007 Pleiades Publishing, Ltd

Effects of blockade of hyperpolarization-activated ion currents (Ih) on autonomic control of the heart in rats: Age-related peculiarities

In our experiments, we studied the effects of intravenous introduction of ZD7288, a selective blocker of the currents activated by hyperpolarization (Ih), on the cardial activity of 1- and 3-week-old and young adult (20-week-old) rats. Introduction of the blocker caused a dose-dependent decrease in the heart rate (HR) in all age groups. A maximum and a minimum expression of bradycardia were observed in 1- and 3-week-old rats, respectively. Stimulation of the n. vagus against the background of bradycardia that developed after the blockade of Ih led to a further drop in the HR. In this case, the expression of the effect of stimulation of the n. vagus depended on the dose of the introduced blocker. The blockade of Ih influenced the cardial reaction to introduction of an agonist of β-adrenoreceptors, isoproterenol, in rats of early age and young adult rats, but not in 3-week-old rats. Therefore, the blockade of Ih changes the reaction of the heart on sympathetic and parasympathetic regulatory influences, and the expression of these changes significantly depends on the animal's age. This allows us to conclude that not only the pacemaker activity of cardiomyocytes per se but also autonomic modulation of the cardial activity demonstrate a significant dependence on the function of hyperpolarization-activated ionic channels; this function is characterized by substantial age-related peculiarities. © 2003 Plenum Publishing Corporation

Age-related peculiarities of the effect of α-adrenoceptor blockade on cardiac function in rats

Blockade of α1-adrenoreceptors with prazosin produces bradycardia. The degree of this bradycardia in rats depends on age. In adult (20-week-old) rats bradycardia is pronounced, in 3-week-old rats it is insignificant, and in 1-week-old rats bradycardia does not develop. Prazosin moderates bradycardia induced by vagal stimulation in rats of different age

Determination of Sterically Hindered Phenols and α-Tocopherol by Cyclic Voltammetry

Sterically hindered phenols (2,6-di-tert-butyl-4-methylphenol (BHT) and its derivatives) are irreversibly oxidized at +0.96-1.30 V on glassy carbon electrode (GCE) in 0.1 M LiCIO4 in acetonitrile in accordance to cyclic voltammetry data. α-Tocopherol gives oxidation step at +0.4 V on voltammograms under the same conditions. Oxidation process leads to formation of corresponding quinoid derivatives. Calibration graphs linearity is 1.5-2 order for all compounds under investigation. Limits of detection are in the range 9.6-44.3 μM. The approach has been applied for determination of BHT and α-tocopherol in vegetable and lubricating oils as well as pharmaceuticals and cosmetics using preliminary single extraction of analytes with acetonitrile for 15 min at oil/extractant ratio of 1:2.5. © 2012 Copyright Taylor and Francis Group, LLC

Voltammetric determination of curcumin in spices

Curcumin is oxidized on a glassy carbon electrode in 0.1 M LiClO 4 in ethanol at the potential 0.74 V. The calibration graph is linear in the range 9.9 × 10 -6-1.07 × 10 -4 M curcumin; the detection limit is 4.1 × 10 -6 M. Curcumin is determined in model solutions. The relative standard deviation does not exceed 0.05. A procedure is proposed for the voltammetric determination of curcumin in spices. It was shown that single extraction by ethanol quantitatively recovers curcumin from spices. © 2012 Pleiades Publishing, Inc

Peculiarities of regulation of heart rate and stroke volume in rats during ontogeny

Changes in heart rate and stroke volume after successive blockade of cardiac adrenoand cholinoceptors were examined on rats of different age. It was established that irrespective of animal age the heart rate remained unchanged under conditions of total adreno-and cholinergic blockade of the heart. Stroke volume under conditions of total adreno-and cholinergic blockade increased with age. © Springer Science+Business Media, Inc. 2006

Iron(III) Salicylate complexes in surfactant solutions

Electron spectroscopy combined with the computer simulation of experimental data is employed to study the influence of different surfactants on the equilibria involved in the formation processes of bis- and tris(ligand) complexes of iron with salicylic acid (H 2L). It is established that the formation of tris(ligand) complexes FeL 3 is stimulated by both micelles and premicellar aggregates of cationic surfactants in the presence of excess ligand and only by premicellar aggregates at the deficiency of the ligand. The replacement of pyridinium head group by trimethylammonium group decreases the effect, while the application of cationic surfactants with hexadecyl radicals reduces the solubility of the complexes in water. © Pleiades Publishing, Ltd., 2011

Reactions of synthetic phenolic antioxidants with electrogenerated titrants and their analytical applications

Synthetic phenolic compounds (pyrogallol, catechol, hydroquinone, and their derivatives bearing heterocyclic fragments) react with electrogenerated titrants, halogens, and ferricyanide(III) ions. Stoichio- metric coefficients of reactions are found. It is shown that the use of ferricyanide(III) ions as a titrant and a one-electron oxidant for the determination of this class of antioxidants offers advantages in comparison with titrants-halogens. The found amounts of pyrogallol, pyrocatechol, and hydroquinone derivatives in model solutions with the RSD 1-5% are fractions of milligrams. It is found that, in the series of the studied synthetic phenolic compounds, pyrocatechol derivatives possess the maximum antioxidant capacity (AOC). © Pleiades Publishing, Ltd., 2010

Age-related peculiarities of inotropic response of rat myocardium to selective block of M1-cholinoreceptors

In vitro effect of M1-cholinoreceptor blockade on the cardiac inotropic function was examined in rats aging 1, 3, 6, 8, and 20 weeks. In 1- and 3-week old rat pups, the sympathetic control of the heart has not developed, the age of 7-8 weeks being pubertal. Adult 20-week rats were used as the controls. In rats of all age groups, preliminary blockade of M1-cholinoreceptors did not prevent the inhibitory effect of carbacholine on contractility of the atrial and ventricular myocardium. The inhibitory effect of pirenzepine on the contractile force of ventricular myocardium was revealed in 6-week rats. © 2013 Springer Science+Business Media New York