Cardioprotective Effect of Modified Peroxiredoxins in Retrograde Perfusion of Isolated Rat Heart under Conditions of Oxidative Stress.

Antioxidant properties of recombinant peroxiredoxin-6 and chimeric protein PSH combining peroxidase and superoxide dismutase activities were studied on the model of retrograde perfusion of isolated rat heart under conditions of H2O2-induced oxidative stress. The exogenous antioxidant proteins exhibited cardioprotective properties manifested in heart rate normalization, maintenance of contractile activity of the myocardium, and prevention of H2O2-induced LPO in oxidative stress. Localization of peroxiredoxin-6 and PSH in the cardiac tissue was determined and myocardial structures most effectively protected by the antioxidant enzymes from ischemia/reperfusion-induced damages were identified. The results suggest that modified peroxiredoxins are promising components of perfusion media for preservation of isolated organs.

[Specific molecular and morphological changes in cardiomyocytes of hibernating ground squirrels in different periods of annual cycle].

Structural and molecular changes in cardiomyocytes of hibernating ground squirrels in different periods of the annual cycle were analyzed by means of electron microscopy and polymerase chain reaction. Morphological analysis showed an increase in relative area of sarcoplasmic reticulum in cardiac muscle of ground squirrels preparing to torpor compared to active summer animals. The size of sarcoplasmic reticulum in cardiomyocytes of torpid animals was reliably less than in any other condition of ground squirrels in the annual cycle. The results of molecular analysis showed the decrease in sarcoplasmic reticulum Ca(2+)-ATPase gene (SERCA2a) expression .at all stages of hibernation process and also in periods of autumn activity compared to control mRNA level in active summer animals. The revealed season changes in structure of sarcoplasmic reticulum and sarcoplasmic reticulum Ca(2+)-ATPase gene expression are discussed in regard to adaptation of ground squirrels to hibernation.

[Role of light chains of myosin in the regulation of contraction of vertebrate striated muscles].

The data of the study on Ca2+ sensitivity of ATPase activity of myosin from vertebrate striated muscles in the presence of actin and the conditions of its manifestation and disappearance are presented. The role of Ca2+ sensitivity of actin-activated myosin ATPase in the regulation of contraction of vertebrate striated muscles is discussed.

[Expression of titin in the myocardium of spontaneously hypertensive rats during in the course of hypertrophy].

Changes in the expression of N2B- and N2BA-isoforms of titin in the left ventricle of the myocardium of spontaneously hypertensive rats during the development of hypertrophy have been analyzed by the methods of real-time scale polymerase chain reaction and SDS gel electrophoresis. It was shown that, in early development of hypertrophy (15-week-old rats), an increase in the expression of mRNA of the titin gene and a decrease in the content of the protein itself occur. At a later stage of development (26-week-old rats), a decrease in the expression of titin at the level of both mRNA and the protein per se was observed. The results obtained can be used in the development of methods for diagnosing the development of myocardium hypertrophy.

[Contractile properties of fibers and cytoskeletal proteins of gerbil's hindlimb muscles after space flight].

The work had the goal to compare the microgravity effects on gerbil's muscles-antagonists, m. soleus and m. tibialis anterior. The animals were exposed in 12-d space microgravity aboard Earth's artificial satellite "Foton-M3". Findings of the analysis of single skinned fibers contractility are 19.7% diminution of the diameter and 21.8% loss of the total contractive force of m. soleus fibers post flight. However, there was no significant difference in calcium sensitivity which agrees with the absence of changes in the relative content of several major cytoskeletal proteins (titin and nebulin ratios to heavy chains of myosin were identical in the flight and control groups) and a slight shifting of the myosin phenotype toward the "fast type" (9%, p < 0.05). These parameters were mostly unaffected by the space flight in m. tibialis anterior. To sum up, the decline of contractility and diminution of gerbil's myofibers after the space flight were less significant as compared with rats and did not impact the sytoskeletal protein ratios.

[Seasonal changes in the composition of the titin isoforms in muscles of hibernating ground squirrels].

An electrophoretic study of changes in the content of intact titin isoforms, N2B-, N2BA-, N2A-titins and T2 in skeletal and cardiac muscles of ground squirrel (Spermophillus undulatus) in different periods: summer activity, autumn activity, hibernation, arousal, and winter activity has been carried out. In atriums and ventricles of autumn activity ground squirrels, an increase (approximately 1.5 times) in the N2BA-to-N2B ratio in comparison with that in cardiac muscle of summer activity ground squirrels has been observed. During hibernation, the decrease in the relative content of N2B,- N2BA-titins and T2 in cardiac muscle and of N2A-titin and T2 in skeletal muscles has been tested against the background of preservation of the relative amount of intact titin isoforms. During arousal of ground squirrel and in short-time period of winter activity, a rapid restoration in the content of N2B,- N2BA-, N2A-titins and T2 in muscles has been observed. In this case, in cardiac muscle of hibernating, arousing and winter active ground squirrels, the increased N2BA-to-N2B ratio has been preserved. The changes in the titin content are discussed in the context of adaptation of ground squirrels to hibernation.