Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “GRAVITATION”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 811 records · Page 45Linked to original sources
PubMedDate not supplied

[Effect of periodic gravitation overloads on the physico-chemical properties and Ca2+ reactivity of actomyosin of the myocardium and skeletal muscles of albino rats].

Under the influence of regular acceleration (5 g for 25 min during 15 days) Mg2+-ATPase activity of native and desensitized actomyosin of the myocardium and femurs of white rats increased. This was in correlation with increases in the rate of actomyosin superprecipitation (Vspp) and in the surface charge of macromolecules. The control animals showed a decrease in the inhibition of Mg2+-ATPase and Vspp of native actomyosin by tropomyosin-troponin. Ca2+ in a concentration of 10(-7) - 10(-4) M stimulated Mg2+-ATPase of native actomyosin of experimental animals by 50% only, but the maximum activation of Vspp was significantly higher than in the controls. It is assumed that these changes tend to increase the efficiency of the actomyosin system.

Acceleration↗
PubMedDate not supplied

[Tolerance of +G2 gravitation overload in persons aged 41-58 years].

Forty-five men (non-pilots) aged 41-58 were used in 186 experimental runs to study their tolerance to +GZ acceleration. The test subjects were either healthy people or showed atherosclerotic symptoms (the number of which varied from 1-2 to 5 and more). During centrifugation the test subjects had no anti-G suits on. Healthy test subjects exhibited high tolerance to +Gz acceleration of up to 5 g in most centrifugal runs (90.3%). The test subjects with early atherosclerotic changes showed a significantly lower tolerance as compared to the matched controls. It was found that in the atherosclerotic subjects tolerance to +Gz acceleration decreased as its value increased and as the number of atherosclerotic symptoms grew. The major symptoms that limited tolerance to +Gz acceleration in all the test subjects were cardiac arrhythmias and in the atherosclerotic subjects they were also eye disorders and autonomic-vascular reactions during recovery. The data obtained show that it is important to measure individual tolerance to acceleration in people aged 41-58 years old.

Acceleration↗
PubMed1978

Effect of gravitational and inertial forces on vertical distribution of pulmonary blood flow.

Vertical distribution of pulmonary blood flow (VDPBF) was studied, using radioactive microsphere emboli, in dogs without thoracotomy in the right decubitus position during exposure to lateral (--Gy) accelerations of 1, 2, 4, and 6 G. At all levels of force environment studied, an inverse linear relationship was observed between vertical height in the thorax and pulmonary blood flow (ml/min/ml lung tissue) with a decrease in flow to the most dependent region of the lung despite large increases in intravascular pressures at this site. Changes in blood flow were smallest at the mid-lung level, the hydrostatic "balance point" for vascular and pleural pressures. These force environment-dependent changes in VDPBF are not readily explainable by the Starling resistor analog. Gravity-dependent regional differences in pleural and associated interstitial pressures, plus possible changes in vascular tone resulting from inadequate aeration of blood in the most dependent regions of the lung, probably also affect VDPBF.

Acceleration↗
PubMedDate not supplied

[Role of gravitational force in the early embryogenesis of the teleost Brachidanio rerio].

The effect of turning and clinostating, exposures on the early embryogenesis of the teleost B. rerio was investigated. The eggs turned immediately after fertilization with their animal pole downwards and kept so till the formation of the axial complex developed in an absolutely normal way. Most eggs also developed normally during clinostating, when kept in the inclined and horizontal clinostats. During this exposure eggs of some clutches perished. They were those eggs which were unable to develop near the lower limits of the temperature range characteristic of B. rerio development (18-19.5 degrees C).

Animals↗