[Dynamics of ECG voltage in changing gravity].

Comparative analysis of the QRS voltage response to gravity variations was made using the data about 26 normal human subjects collected in parabolic flights (CNERS-AIRBUS A300 Zero-G, n=23; IL-76MD, n=3) and during the tilt test (head-up tilt at 70 degrees for a min and head-down tilt at-15 degrees for 5 min, n=14). Both the parabolic flights and provocative tilt tests affected R-amplitude in the Z lead. During the hypergravity episodes it was observed in 95% of cases with the mean gain of 16% and maximal--56%.

[Reactions of the human bone system in space flight: phenomenology].

Results of multi-year bone observations in crewmembers of long-term (6 to 14 mos.) Salyut and Mir missions have been summarized. The theoretical expectation of bone losses (mineral bone density, MBD) was consistent only in the trabecular of the lower skeleton (lumbar spine, femur proximal epiphysis, pelvis).

ECG voltage modifications as response to gravity changes.

The aim of the study was to analyze ECG (QRS) voltage responses to body fluid shift due to gravity chances. Acute changes in gravity were created by two ways: 1) changes in gravity value during parabolic flights (within 27 subjects 45 ECG have been analyzed); 2) changes in gravity direction due to rotation of the body during postural tests (within 11 subjects 14 ECG have been analyzed). Results and conclusions.

Ephaptic feedback in identified synapses in mollusk neurons.

The possible existence of intrasynaptic ephaptic feedback in the invertebrate CNS was studied. Intracellular recordings were made of excitatory postsynaptic potentials and currents arising on activation of the recently described monosynaptic connection between identified neurons in the snail CNS. In the presence of ephaptic feedback, tetanization of the postsynaptic neuron with hyperpolarizing impulses should activate presynaptic calcium channels, thus increasing the amplitude of excitatory postsynaptic potential, while sufficiently strong postsynaptic hyperpolarization applied during generation of the excitatory postsynaptic current should induce "supralinear" increases in its amplitude, as has been observed previously in rat hippocampal neurons.

Bone mineral and lean tissue loss after long duration space flight.

The loss of bone and muscle is a major concern for long duration space flight. In December of 1989, we established a collaboration with Russian colleagues to determine the bone and lean tissue changes in cosmonauts before and after flights on the Mir space station lasting 4-14.4 months.