[Mechanisms of development of cardiac insufficiency in old age]. / Mekhanizmy razvitiia serdechnoi nedostatochnosti v starosti

Tests conducted with adult (8--10 months) and old (26--28 months) rats brought evidence that in ageing the cardiac ejection, dp/dt max, contractility index, the ATP concentration, that of creatinophosphate, glycogen, pyruvate decline, the phosphorylation coefficient, the lactate content increase, while the level of water-soluble proteins and collagen diminishes and that of water-insoluble ones decreases. In adult rats hemodynamics and myocardial contractility change but unsignificantly on the 4--6th day after coarctation of the aorta, whereas in the old ones there occur functional and metabolic alterations in the heart that are indicative of a developing cardiac insufficiency. The age-specific differences persist also on the 14--16th day following coarctation of the aorta. During these periods the weight of the heart, the content of the myofribrillary proteins and collagen are on the rise, whereas in the old ones the weight of the heart remains unchanged and the level of water-soluble protein drops. Changes in the properties of the actomyosin complex, disruption of the calcium pump, shifts in the system of the energy generation, limitation of potential possibilities incident to the systems of protein biosynthesis in the myocardial cell, all this leads to the development of cardiac incompetence following loading in old age.

[Hormonal regulation of the heart in aging]. / Gormonal'naia reguliatsiia serdtsa pri starenii.

It was established in experiments on adult (8--12 month) and old (26--32 month) rats that in ageing the sensitivity of the cardiovascular system to certain hormones--adrenaline, vasopressin, insulin, thyroxine, estradiol dipropionate--grows while its reactivity to them diminishes. The administration of these hormones causes significant changes in hemodynamics and myocardial contractility. Adrenaline and thyroxine lead to an increase in the blood minute and stroke volume, arterial pressure, cardiac index and left ventricular work index, maximum rate of intraventricular pressure growth, maximum rate of myocardial fiber shortening, and in the contrastility index. Vasopressin and insulin cause a decrease in the indices of general hemodynamics. The increased sensitivity of the heart to hormones at old age and diminution of its reactivity lead to prolonged, protracted reactions of the cardiovascular system in elderly and old individuals.

[Nervous regulation of cardiac function during aging]. / Nervnaia reguliatsiia funktsii serdtsa pri starenii.

The hemodynamic changes and myocardium contractile capacity following the extracardiac nerves stimulation with acetylcholine, norepinephrine, inderal, regitin and atropine, as well as the activity of main enzymes of cholinergic and adrenergic metabolism, were studied in albino rats, rabbits, and cats of various age. With ageing, the thresholds of vagal and sympathetic nerves influences on the heart increased, the sensitivity of heart to acetylcholine and norepinephrine changed. In old animals, smaller atropine and in deral doses blocked the respective cholinergic and beta-adrenergic reactions. Alterations of transmitters metabolism play an important role in the mechanism of age-induced changes in nervous control of cardiac function.

[The effect of polyfunctional macroheterocycles on the rhythmic and contractile activity of the myocardium in animals]. / Vliianie polifunktsional'nykh makrogeterotsiklov na ritmicheskuiu i sokratitel'nuiu aktivnost' miokarda zhivotnykh.

The effect of the polyfunctional macroheterocycles on the rhythmic and contractile activity of the rat myocardium was found to depend on their concentration. A two-phasic effect upon contractility of the papillary muscles was revealed: a short-term (up to 20 sec) positive inotropic effect followed by a stable depression. The most active drug of this class, dicyclohexano-18-crown-6, prevented the positive inotropic action of classic stimulants (catecholamines and strophantin) upon the contractile function of the heart.

[Role of protein biosynthesis activation in the mechanism of the negative chronotropic action of the vagus nerve and acetylcholine on the heart]. / Rol'aktivatsii biosinteza belka v mekhanizme otritsatel'nogo khronotropnogo deistviia bluzhdaiushchego nerva i atsetilkholina na serdtse.

In rats, the following data were obtained: a) acetylcholine activates the rate of protein biosynthesis in auricles in vitro; b) protein biosynthesis inhibitors (actinomycine D, sarcolysine, neutral rot, tolluidine blue) weaken the negative chronotropic effect of acetylcholine and vagus on the heart; c) anabolic hormones increase the cholinergic effect on heart; d) acetylcholine induces hyperpolarization of the myocardial fibers which is prevented by actinomycine D. The activation of protein biosynthesis followed by hyperpolarization of the pacemaker cells seems to play an important role in the mechanism of negative chronotropic effect of acetylcholine and vagus on the heart.

[The contractile function and calcium-transport system of the myocardium in aging]. / Sokratitel'naia funktsiia i kal'tsii-transportnaia sistema miokarda pri starenii.

Experiments with different species of animals and different models (in situ heart, isolated perfused heart, isolated papillary muscle) revealed a reduction of functional capacity of ageing heart. A decrease of Ca2+ uptake by sarcoplasmic reticulum and mitochondria and diverse age-dependent shifts were found in sarcolemma. The data obtained suggest that the development of the cardiac contractile function disorders in ageing largely depends of the age-related changes in the Ca2+ transport system.

[Structural effects in the sarcolemma of the cardiomyocytes under the action of modulators of the polyphosphoinositide system]. / Strukturnye éffekty v sarkolemme kardiomiotsitov pri deistvii moduliatorov polifosfoinozitidnoi sistemy.

The influence of activators (Ca(2+)-channels stimulator BAY K 8644 and phospholipase C stimulator fMLP) and inhibitors (Ca(2+)-channels blocker verapamil and alpha 1-adrenoceptors blocker prazosin) of the polyphosphoinositide system on cardiomyocytes sarcolemma, was studied. The structural effects of the PPI modifiers seem to be one of the mechanisms of the PPI physiological activity at the membrane level.

[Effect of caffeine on chronotropic correlations in the myocardium of the rat and guinea pig]. / Vliianie kofeina na khronoinotropnye vzaimootnosheniia v miokarde krysy i morskoi svinki.

Force-frequency relations in the isolated papillary muscles of rats and guinea-pigs were compared using isometric force measurement technique. Stimulation frequency varied between 0.33 and 4 Hz. Under normal conditions the rat papillary muscle exhibits a negative force-frequency dependence which differs from ventricular preparations in many other mammals. Caffeine (10 mmol/l) introduced into the bath solution abolishes a negative force-frequency dependence in the papillary muscle of rat. During incubation of the rat ventricular preparations in the caffeine-containing solution the force-frequency relations measured on these muscles display the same behaviour as in guinea pig preparations. Caffeine has induced no changes in the force-frequency relations of guinea-pig ventricular preparations. A conclusion is made that caffeine-sensitive intracellular calcium stores participate in species-determined differences in force-frequency relations of the ventricular muscles.

[Effect of retabolil, biosed and vitreous body on reparative processes in the heart of rats with experimental myocardial infarction]. / Vliianie retabolila, bioseda i steklovidnogo tela na reparativnye protsessy v serdtse krys s éksperimental'nym infarktom miokarda.

Influence of retabolilum, biossedum and corpus vitreum on the inflammation and reparation in the rat heart with experimental infarction has been investigated. It is shown that retabolilum has the most pronounced reparation effect. At the same time biossedum has a slight effect on the reparative processes and corpus vitreum does not influence it al all. It is also found that the most pronounced action of retabolilum has been observed by the 12th day of infarction.