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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 703 records · Page 39
All sourcesNASA NTRSDOE OSTI
NASA NTRS1970

EMG-force dynamics in human skeletal muscle

On-line parameter tracking algorithm, obtaining parameters in mathematical relation between full wave rectified EMG and human triceps muscle force during isometric task

Bekey, G. A.↗
NASA NTRS1972

Skin and muscle components of forearm blood flow in directly heated resting man.

Changes in forearm muscle blood flow (FMBF) during direct whole-body heating were measured in 17 normal subjects using three different methods. We conclude that FMBF is not increased by direct whole-body heating. Since renal and splanchnic blood flow fall 30% under these conditions, maximal total skin blood flow in 12 previously studied subjects can be estimated from the rise in cardiac output to be 7.6 L/min (3.0-11.1 L/min).

Detry, J.-M. R.↗
NASA NTRS1980

Effect of hypokinesia on contractile function of cardiac muscle

Rats were subjected to hypokinesia for two months and the contractile function of isolated papillary muscle was studied. Hypokinesia reduced significantly the isotonic contraction rate which depended on the ATPase activity of the myofibrils; it also reduced the rate and index of relaxation which depended on the functional capacity of the Ca(++) pump of the sarcoplasmic reticulum. The maximum force of isometric contraction determined by the quantity of actomyosin bridges in the myofibrils did not change after hypokinesia. This complex of changes is contrary to that observed in adaptation to exercise when the rate of isotonic contraction and relaxation increases while the force of isometric contraction does not change. The possible mechanism of this stability of the contractile force during adaptation and readaptation of the heart is discussed.

Meyerson, F. Z.↗
NASA NTRS1980

Content of total iron, copper and manganese in liver of animals during hypokinesia, muscle activity and process of recovery

It is shown that the content of total iron, copper and manganese in the liver of animals is altered depending on the intensity and duration of their swimming. Hypodynamia for 7 days does not alter the concentration of iron, but sufficiently increases the content of copper and manganese. The barometric factor effectively influences the maintenance of constancy in the content of microelements accumulated in the liver after intensive muscle activity.

Potapovich, G. M.↗
NASA NTRS1980

Ultrastructural studies of the mitochondriae in the striated muscles of birds with regard to experimental hypokinesis

Electron microscopic studies were carried out on the mitochrondria of the transversely striated muscles with regard to experimental hypokinesia. As compared to the central group the mitochondria of m. pectoralis thoracicus and the m. iliotibialis posterior in hypokinetic birds reveal marked changes. In filamentous and ovoid mitochondria, vacuoles can be observed which in some cases produced larger light formations with following disappearance of the cristae and destruction of mitochondria. Fat particles located at the poles of the altered mitochondria, sporadically occurring also laterally, presented another finding. The Z-lines of the sarcomere did not form a continuous line, but were somewhat shifted.

Belak, M.↗
NASA NTRS1981

Electron microscopical and histochemical studies on the transverse striated muscles of birds after prolonged hypokinesis

Studies of the gastrocnemius muscle were carried out in 4 month old cockerels of the laying hybrid after hypokinesis lasting 15 and 30 days. It was found that restricted movement resulted in dystrophic changes of myotibrils, enlargement of the sarcoplasmic reticulum and oedem of interfibrillar spaces. Histochemical studies revealed focuses of increased activity of non-specific esterase, decreased activity of dehydrogenase of lactic acid and a positive reaction of acid phosphatase.

Belak, M.↗