[Effects of weak magnetic fields on the production of reactive oxygen species in peritoneal neutrophils in mice].

The influence of weak magnetic fields of different types on the rate of the formation of reactive oxygen species in mouse peritoneal neutrophils has been studied. It was found that the exposure of neutrophils activated by phorbol 12-myristate 13-acetate to the magnetic field tuned to the parametric resonance for Ca2+ ions leads to a decrease in the rate of the reactive oxygen species (ROS) generation by 23%. Conversely, the generation of ROS in neutrophils exposed to the same field but stimulated by the bacterial peptide FMLP (N-formyl-L-methionyl-L-leucyl-L-phenylalanine) increased by about 21%. Pulsed magnetic fields also changed the rate of ROS generation in phorbol-stimulated neutrophils by about 20%, but the sign of the effects observed in this case was opposite to those induced by the magnetic field tuned to the parametric resonance for Ca2+ ions.

[Effect of the extremely weak alternating magnetic fields on the regeneration of planarians and the gravitropic response of plants].

The influence of extremely weak alternating magnetic fields (EW AMF) directed colinearly to the static Earth magnetic field on the rate of regeneration of planarians and the rate of gravitropic response in the stem segments of flax has been studied. The value of bioeffects of EW AMF is determined by the parameter gamma B(AC)/f, where y is the gyromagnetic ratio of the magnetic moments induced by the orbital movements of electrons in atoms, and B(AC) and f correspond to magnetic induction and frequency of the alternating magnetic component. It was shown that the magnitude of bioeffects depends on the amplitude (at fixed 1000 Hz - frequency) and frequency (at fixed 192 nT - amplitude) of the alternating component. Maxima of bioeffects are observed at gamma B(AC)/f = 0.9; 2.75, and minor maxima gamma B(AC)/f = 4.5; 6.1. The bioeffects are absent at gamma B(AC)/f = 1.8, 3.8, 5.3, 6.7. The positions of the maxima and minima of bioeffects correspond to the theoretical prediction (at gamma = 14000 Hz/microT). Primary targets for the EW AMF of this type are the magnetic moments induced by the orbital movements of electrons in atoms.

[Monitoring the orientation of myosin bridges on two-dimensional maps of birefringence in a single muscle fiber]. / Monitoring orientatsii miozinovykh mostikov po dvukhmernym kartam dvulucheprelomleniia v odinochnykh myshechnykh voloknakh.

Two-dimensional maps of birefringence in sarcomers of a single fiber of rabbit m.psoas were obtained by an automated interference microscope developed at our laboratory. The changes in birefringence of muscle fibers reflect the movement of myosin cross-bridges. The orientation of cross-bridges was modified by varying the pH (pH 7.0, 6.0, 8.0) and ionic strength (mu = 0.115, 0.085, 0.235) of the bathing rigor solution. The maximum value of total birefringence in the rigor state was observed at neutral pH. Total birefringence markedly decreased (by 40%) as pH was changed from 7.0 to both 8.0 and 6.0. No significant changes in light phase shifts were found at a 1.5 reduction of ionic strength in the rigor solution. The calculated birefringence values were 45% higher in rigor solutions of a high (mu = 0.235) ionic strength. The results observed are discussed in terms of changes in the orientation of cross-bridges due to the movement of the alpha-helical subfragment-2 away from the filament shaft (pH 8) or coming closer to it (mu = 0.235). The available data do not allow one to explain the results obtained at pH 6.0.

[Two-dimensional reconstruction of birefringence map of the skeletal muscle sarcomere in relaxed and rigor states studied by interference microscopy]. / Dvumernaia rekonstruktsiia karty dvulucheprelomleniia sarcomera skeletnoi myshtsy v relaksirovannom i rigornom sostoianii po dannym interferentsionnoi mikroskopii.

A new method of automatized quantitative interferometry of skeletal muscle fibers was developed for the investigation of birefringence. A device based on the Linnic microscope was constructed to obtain phase images, which are two-dimensional pictures of birefringence. For the first time, two-and-three-dimensional maps of both total birefringence and birefringence for individual sarcomeres in the central part of muscle fiber were visualized using large databases. It was shown that total birefringence of fibers at rest length in the rigor state was lower as compared with the relaxed. Birefringence values from individual sarcomere interferograms revealed also that normalized A-disk birefringence was lower in the rigor state. The results obtained could be explained by a decrease of thick filaments anisotropy, due to the moving away of myosin heads from the rod during transition into the rigor state.

[Ca2+ localization in muscles with double calcium regulation]. / Lokalizatsiia Ca2+ v myshtsakh s dvoinoi kal'tsievoi reguliatsiei.

Localization of Ca-accumulating structures was studied in scutal depressor muscles of barnacle (Balanus rostratus) by electron microscopy combined with osmium--pyroantimonate technique. In resting fibers the pyroantimonate precipitate was localized mainly in plasma membranes of the cleft system which can be considered as main calcium store. The precipitate was also located in membranes of sarcoplasmic reticulum and mitochondria and I--bonds diffusely. In contracted fibers fixed at the peak of mechanical activity the number of precipitate granules increased in the sarcoplasm and diminished at cleft plasma membranes. In contracted fibres the fine precipitate also appeared along thick filaments at the sites of myosin heads. The latter seems to be the proof of the presence of myosin control in crayfish muscles.