Selective blockade of α<inf>2</inf>-adrenoceptor subtypes modulates contractility of rat myocardium

© 2016 Springer Science+Business Media New York.The study examined the dose-dependent effects of selective antagonists of α2A/D-, α2B-, and α2C-adrenoceptors applied in concentrations of 10-9-10-5 M on atrial and ventricular contractility of rat myocardium in vitro. Selective blockade of each α2-adrenoceptor subtype affected the contractile force of the atrial and ventricular strips. Various concentrations of α2A/D-and α2C-adrenoceptor antagonists produced positive inotropic effect on ventricular strips and negative effect on atrial strips. α2B-Adrenoceptor blocker in the majority of the tested concentrations produced a positive inotropic effect in both atria and ventricles

Effect of α2-adrenoceptor stimulation on cardiac activity in rats

We studied the effect of α2-adrenoceptor stimulation with clonidine on BP and cardiac activity in rats. Variations in BP and chronotropism of the heart were studied in vivo after bolus injection of clonidine. In vitro experiments were performed to evaluate a dose-dependent change in myocardial contractility of the atria and ventricles after treatment with clonidine in concentrations of 10-9-10-5 M. α2- Adrenoceptor stimulation with clonidine had a negative chronotropic and inotropic effect and induced the decrease in systolic BP of rats. © 2014 Springer Science+Business Media

Peculiar Effects of Selective Blockade of α2-Adrenoceptor Subtypes on Cardiac Chronotropy in Newborn Rats

© 2015, Springer Science+Business Media New York. We studied the effects of selective blockade of various subtypes of α2-adrenoceptors on cardiac chronotropy in newborn rats. This period in rats is characterized by the absence of adrenergic regulation of heart function. Blockade of α2A/D- and α2B-adrenoceptors in 1-weekold rats provoked tachycardia. In contrast, blockade of α2C-adrenoceptors in newborn rats had no effect on heart rate

Selective Blockade of α<inf>2</inf>-Adrenoceptor Subtypes Modulates Contractility of Rat Myocardium

© 2016 Springer Science+Business Media New YorkThe study examined the dose-dependent effects of selective antagonists of α2A/D-, α2B-, and α2C- adrenoceptors applied in concentrations of 10—9-10—5 M on atrial and ventricular contractility of rat myocardium in vitro. Selective blockade of each α2-adrenoceptor subtype affected the contractile force of the atrial and ventricular strips. Various concentrations of α2A/D- and α2C-adrenoceptor antagonists produced positive inotropic effect on ventricular strips and negative effect on atrial strips. α2B-Adrenoceptor blocker in the majority of the tested concentrations produced a positive inotropic effect in both atria and ventricles

The effect of blockade of α<inf>2A/D</inf>-adrenoreceptors on myocardial contractility in developing rats

© 2016,International Journal of Pharmacy and Technology. All rights reserved.Previously,it was believed that α2-AR in the mammal heart modulate regulatory influence,by ranging presynaptically and regulating the release of norepinephrine. Currently,it is known that α2-AR are present in the smooth vascular muscles,on the presynaptic adrenergic fiber membranes,and on the postsynaptic membranes of myocardiocytes. Further investigation of the functional characteristics of α2-adrenergic receptor subtypes will help to clarify their role in the regulation of the cardiovascular system of the developing organism. We studied in vitro the contractile activity of the myocardium strips. The atria and ventricle strips of rats at different stages of early postnatal ontogenesis were placed in the reservoir with process solution. To solve the set problem,the process solution was added with selective blocker α2A/D-АR (RX 821002),at a concentration of 10-5,10-6,10-7,10-8,-10-9 mol. Contractile force (F) was stated in grams (g). The study of dose-dependent response of myocardial contractile function of the atria and ventricles in rats of different ages to the introduction of α2A/D-adrenergic receptor blocker in the concentration range of 10-9-10-5 has shown that the blockade of the α2A/D-AR subtypes causes multidirectional inotropic effect in animals of different age groups. A multidirectional effect and age characteristics of the blockade α2-adrenergic receptor subtypes may be associated with changes in the synthesis,localization and activity of various receptor structures of the heart

Metastable phases and "metastable" phase diagrams

The work discusses specifics of phase transitions for metastable states of substances. The objects of condensed media physics are primarily equilibrium states of substances with metastable phases viewed as an exception, while the overwhelming majority of organic substances investigated in chemistry are metastable. It turns out that at normal pressure many of simple molecular compounds based on light elements (these include: most hydrocarbons; nitrogen oxides, hydrates, and carbides; carbon oxide (CO); alcohols, glycerin etc) are metastable substances too, i.e. they do not match the Gibbs' free energy minimum for a given chemical composition. At moderate temperatures and pressures, the phase transitions for given metastable phases throughout the entire experimentally accessible time range are reversible with the equilibrium thermodynamics laws obeyed. At sufficiently high pressures (1-10 GPa), most of molecular phases irreversibly transform to more energy efficient polymerized phases, both stable and metastable. These transformations are not consistent with the equality of the Gibbs' free energies between the phases before and after the transition, i.e. they are not phase transitions in "classical" meaning. The resulting polymeric phases at normal pressure can exist at temperatures above the melting one for the initial metastable molecular phase. Striking examples of such polymers are polyethylene and a polymerized modification of CO. Many of energy-intermediate polymeric phases can apparently be synthesized by the "classical" chemistry techniques at normal pressure.Comment: 5 pages, 4 figure

Reação adaptativa do sistema simpático de adrenalina de meninas em atividade física

The study of the functional state of the sympatho-adrenal system in girls of 11-16 years old undergoing graduated physical activity was performed on the basis of excretion rates of epinephrine, norepinephrine, dopamine and DOPA. As a functional test, a graduated cycloergometric load of 50% of the individually determined PWC170 was used. The results obtained made it possible to establish the heterochronic nature of the maturation of the hormonal and mediator links of the sympathetic adrenal system. The highest reactivity of the adrenal link of SAS is observed in girls of 12 years old, the lowest – in senior schoolgirls (15-16 years old). In girls of 12-13 years old, the reaction of urgent adaptation to the graduated physical activity is carried out against a background of high excretion of epinephrine (E), norepinephrine (NE), but without sufficient replenishment of the reserve capabilities of SAS, which is confirmed by minimal shifts in the excretion of dopamine (DA) and DOPA in these age groups. At 14-16 years, moderate shifts of E and NE as a reaction to activity are noted against the background of a significant increase in the excretion of precursors, which characterizes the SAS response to the functional test as more saving, with increasing reserve capacities.El estudio del estado funcional del sistema simpato-adrenal en niñas de 11-16 años sometidas a actividad física graduada se realizó sobre la base de las tasas de excreción de epinefrina, norepinefrina, dopamina y DOPA. Como prueba funcional, se utilizó una carga cicloergométrica graduada del 50% de la PWC170 determinada individualmente. Los resultados obtenidos permitieron establecer la naturaleza heterócrona de la maduración de los enlaces hormonales y mediadores del sistema adrenal simpático. La mayor reactividad del enlace suprarrenal de SAS se observa en niñas de 12 años, la más baja - en niñas de escuela secundaria (15-16 años). En niñas de 12-13 años de edad, la reacción de adaptación urgente a la actividad física gradual se lleva a cabo en un contexto de alta excreción de epinefrina (E), norepinefrina (NE), pero sin un reabastecimiento suficiente de las capacidades de reserva de SAS. que se confirma por cambios mínimos en la excreción de dopamina (DA) y DOPA en estos grupos de edad. A los 14-16 años, se observan cambios moderados de E y NE como reacción a la actividad en el contexto de un aumento significativo en la excreción de precursores, que caracteriza la respuesta SAS a la prueba funcional como más ahorro, con el aumento de la capacidad de reserva.O estudo do estado funcional das raparigas do sistema simpático-envelhecido 11-16 anos, submetidos a actividade física realizada classificados com base em taxas de excreção de epinefrina, norepinefrina, dopamina e DOPA. Como teste funcional, utilizou-se uma carga cicloergométrica graduada de 50% do PWC170 individualmente determinado. Os resultados obtidos permitiram estabelecer a natureza heterocrônica da maturação dos laços hormonais e mediadores do sistema adrenal simpático. A reatividade mais alta do elo adrenal de SAS observa-se em meninas de 12 anos, o mais baixo - em meninas de escola secundária (15-16 anos). Em raparigas com idades entre 12-13, reacção urgente de adaptação gradual da actividade física ocorre em um contexto de elevada excreção de adrenalina (E), norepinefrina (NE), mas sem capacidades de reabastecimento suficientes Reserva SAS. o que é confirmado por alterações mínimas na excreção de dopamina (DA) e DOPA nestes grupos etários. Aos 14-16 anos, E e NE variações moderadas em resposta à actividade no contexto de um aumento significativo da excreção de precursores, o que caracteriza a resposta SAS para um teste funcional, mais economia, com o aumento observado a capacidade de reserva

Blockade of different subtypes of α1-adrenoceptors produces opposite effect on heart chronotropy in newborn rats

We compared the effects of blockade of α1A-, α1-, and α1D-subtypes of α1- adrenoceptors on the cardiac rhythm in newborn rats. Different responses of the heart were observed after blockade of several subtypes of α1- adrenoceptors. Administration of WB 4101, a selective blocker of α1A-adrenoceptors, increased heart rate, while blockade of α1AD-adrenoceptors with BMY 7378 decelerated of heart rhythm. Blockade of α1-adrenoceptors with chloroethylclonidine produced no significant effects on heart chronotropy. © 2012 Springer Science+Business Media New York

Carbon monoxide affects electrical and contractile activity of rat myocardium

<p>Abstract</p> <p>Background</p> <p>Carbon monoxide (CO) is a toxic gas, which also acts in the organism as a neurotransmitter. It is generated as a by-product of heme breakdown catalyzed by heme oxygenase. We have investigated changes in electrical and contractile activity of isolated rat atrial and ventricular myocardium preparations under the influence of CO.</p> <p>Methods</p> <p>Standard microelectrode technique was used for intracellular registration of electrical activity in isolated preparations of atrial and ventricular myocardium. Contractions of atrial myocardial stripes were registered via force transducer.</p> <p>Results</p> <p>CO (10^-4- 10^-3M) caused prominent decrease of action potential duration (APD) in working atrial myocardium as well as significant acceleration of sinus rhythm. In addition CO reduced force of contractions and other parameters of contractile activity. Inhibitor of heme oxygenase zinc protoporphyrin IX exerts opposite effects: prolongation of action potential, reduction of sinus rhythm rate and enhancement of contractile function. Therefore, endogenous CO, which may be generated in the heart due to the presence of active heme oxygenase, is likely to exert the same effects as exogenous CO applied to the perfusing medium. In ventricular myocardium preparations exogenous CO also induced shortening of action potential, while zinc protoporphyrin IX produced the opposite effect.</p> <p>Conclusions</p> <p>Thus, endogenous or exogenous carbon monoxide may act as an important regulator of electrical and contractile cardiac activity.</p

Antioxidative Activity of Ferrocenes Bearing 2,6-Di-Tert-Butylphenol Moieties

The antioxidative activity of ferrocenes bearing either 2,6-di-tert-butylphenol or phenyl groups has been compared using DPPH (1,1-diphenyl-2-picrylhydrazyl) test and in the study of the in vitro impact on lipid peroxidation in rat brain homogenate and on some characteristics of rat liver mitochondria. The results of DPPH test at 20°C show that the activity depends strongly upon the presence of phenolic group but is improved by the influence of ferrocenyl fragment. The activity of N-(3,5-di-tert-butyl-4-hydroxyphenyl)iminomethylferrocene (1), for instance, was 88.4%, which was higher than the activity of a known antioxidant 2,6-di-tert-butyl-4-methylphenol (BHT) (48.5%), whereas the activity of N-phenyl-iminomethylferrocene 2 was almost negligible −2.9%. The data obtained demonstrate that the compounds with 2,6-di-tert-butylphenol moiety are significantly more active than the corresponding phenyl analogues in the in vitro study of lipid peroxidation in rat brain homogenate. Ferrocene 1 performs a promising behavior as an antioxidant and inhibits the calcium-dependent swelling of mitochondria. These results allow us to propose the potential cytoprotective (neuroprotective) effect of ditopic compounds containing antioxidant 2,6-di-tert-butylphenol group and redox active ferrocene fragment