Biophysics Center of Armenian

Molecular hydrogen (H(2)) can be produced via hydrogenases during mixed-acid fermentation by bacteria. Escherichia coli possesses multiple (four) hydrogenases. Hydrogenase 3 (Hyd-3) and probably 4 (Hyd-4) with formate dehydrogenase H (Fdh-H) form two different H(2)-evolving formate hydrogen lyase (FHL) pathways during glucose fermentation. For both FHL forms, the hycB gene coding small subunit of Hyd-3 is required. Formation and activity of FHL also depends on the external pH ([pH](out)) and the presence of formate. FHL is related with the F(0)F(1)-ATPase by supplying reducing equivalents and depending on proton-motive force. Two other hydrogenases, 1 (Hyd-1) and 2 (Hyd-2), are H(2)-oxidizing enzymes during glucose fermentation at neutral and low [pH](out). They operate in a reverse, H(2)-producing mode during glycerol fermentation at neutral [pH](out). Hyd-1 and Hyd-2 activity depends on F(0)F(1). Moreover, Hyd-3 can also work in a reverse mode. Therefore, the operation direction and activity of all Hyd enzymes might determine H(2) production; some metabolic cross-talk between Hyd enzymes is proposed. Manipulating of different Hyd enzymes activity is an effective way to enhance H(2) production by bacteria in biotechnology. Moreover, a novel approach would be the use of glycerol as feedstock in fermentation processes leading to H(2) production, reduced fuels and other chemicals with higher yields than those obtained by common sugars.

Hydration and [3H]ouabain uptake by different tissues of adult male rats were measured immediately after exposure to homogenous 0.2 T steady magnetic field. A time-dependent decrease of hydration and adaptation, followed by disadaptation, was detected in brain and liver tissues in most of the rats after 3.5-5 h of exposure. The number of functional active ouabain binding receptors, which correlates with cell volume, was also decreased in brain, liver, and spleen and increased in kidney tissue after half an hour of exposure. It is suggested that cell hydration is a second messenger through which the SMF exerts its influence.

The authors studied the effect of the ketamine anesthetic on hydration of tumoral and normal glandular cells and on the binding of labelled ouabain with the tissues in order to reveal changes in the number of active Na-K-ATPase molecules on the cell membrane. Hydration of tumoral and normal cells diminished in one-hour incubation in a solution of narcotic and subnarcotic doses of ketamine based on Tyrode's solution. The binding of ouabain by 3H also sharply reduced in a concentration of 10(-8) M in 30 min incubation, after incubation of pieces of tissues in ketamine, which was also evidence of reduction of the cell volume. This proves that the content of water in the tumoral cells increases and that ketamine in subnarcotic doses exerts a selective effect on tumoral cells.

“Previously, it was hypothesized that the over-hydration of excitable cells leading to the abnormal excitation of the membrane, which transmits the nerve signal to the central neuronal system, can generate pain sensation. To check this hypothesis by means of painless and painful heating of experimental animals with “hot plate” method the hydration sensitivity of several body areas to pain was studied.