[Electron microscope study of protein P55 interaction with myosin]. / Elektronno-mikroskopicheskoe issledovanie vzaimodeistviia belka P55 s miozinom.

It was shown by electron microscopic study that in the presence of inhibitor of myosin ATPase protein P55 the long fibrils of myosin became short.

[Effect of 7-day immersion hypokinesia on the characteristics of precise movements]. / Vliianie 7-sutochnoi immersionnoi gipokinezii na kharakteristiki tochnostnykh dvizhenii.

Experiments were carried out to study the effect of 7-day immersion hypokinesia on precision movements that included reproduction of a certain isometric strain of leg muscles (30% from the maximum voluntary level) and angular displacement of the ankle (15 degrees) relative to the 90 degrees position. On the first postimmersion day the precision level deteriorated, i. e., the error and variability of the movements to be reproduced consistently increased. The precision decline was the highest with plantar flexion, when the error of the effort and position reproduction was 24 and 28%, respectively, and the lowest with dorsiflexion, when the error was 17 and 25%, respectively, versus 6-8% in the baseline tests. Precision disorders were seen in the structure of movements which lost their stereotypic pattern and became fragmentary, transforming into slow approximate movements versus the pattern of preimmersion movements that were of a rapid programmed control type. Precision changes during plantar flexion movements were usually excessive, hypermetric and almost twice longer than preimmersion. The origin of the above precision changes seems to be primarily associated with muscle atonia. At the same time data analysis shows that in nearly 50% of cases the values of precision changes in movements of various types (efforts and displacements) and different directions (plantar and dorsiflexion) were correlated. This is suggestive of common central mechanisms underlying their development.

[Comparative analysis of the effect of weightlessness and its model on the velocity-strength properties and tonus of human skeletal muscles]. / Sravnitel'nyi analiz vliianii nevesomosti i ee modelei na skorostno-silovye svoistva i tonus skeletnykh myshts cheloveka.

The effect of various types of support elimination (actual zero-g, water immersion, and head-down tilt) on the strength-velocity properties and tone of leg muscles was investigated. With all the exposures used, there was a high correlation between the tone decrease and the strength potential of antigravitational muscles, as well as the degree of support elimination (immersion and bed rest). This suggests that the tonic changes associated with the decrease of the support input are the major factor responsible for motor disorders during short-term exposures to zero-g.

[Effect of 7-day immersion hyperkinesia on the response-strength properties of human skeletal muscles]. / Vliianie 7-sutochnoi opornoi razgruzki na skorostno-silovye svoistva skeletnykh myshts cheloveka.

By isokinetic dynamometry the effect of 7-day water immersion on the velocity-strength properties of the triceps and anterior tibial muscles was investigated. The exposure decreased significantly the maximum strength of the leg extensors (about 30%); this was seen in a large velocity range (60-180 degrees/s) and during static movements. The decline of the contractile properties of the extensors was also manifested in a significant increase of the ratio of bioelectrical and mechanical effects of contraction which was greatly pronounced during high-load (60 degrees/s) and isometric regimens. The strength properties of the tibial muscle diminished only during isometric contractions. The high rate with which the above changes developed and returned to normal after the exposure (3-5 days) are indicative of their reflex nature and association with mechanisms of tonic disorders due to the lack of support loading.

[Isolation and certain properties of minor protein P55 inhibiting myosin and actinomyosin ATPase activity]. / Vydelenie i nekotorye svoistva minornogo belka P55, ingibiruiushchego ATFaznuiu aktivnost' miozina i aktomiozina.

A method of minor protein P55 isolation from extract of soluble proteins of A-zone of the sarcomere from rabbit skeletal muscle is described. It is shown that this protein inhibits Ca2+-ATPase of myosin and Mg2+-ATPase of reconstructed actomyosin, but it does not affect superprecipitation of actomyosin. The molecular weight which is determined by mobility and its polypeptide chain polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate is about 35 000 dalton.