The effects of melafen (plant growth stimulant) on membrane structure and functions of animal cells were studied. The process of signal transduction from cell surface to intracellular structures and conformation changes in membranes in the presence of this substance were studied by light scatter and differential scanning microcalorimetry. Melafen in a wide range of concentrations (10(-13)-10(-3) M) inhibited Ca(2+) signal system involved in the function of Ca(2+)-dependent K(+) and Cl(-) channels in Ehrlich ascitic carcinoma cells. Being a hydrophilic substance, melafen had little effect on the lipid phase of artificial membranes, but impaired the function state of transformed cell. The importance of studies of transformed cells causes no doubt because of increasing incidence of diseases associated with uncontrolled cell division.

It was shown that low doses of phenozan (10(-17), 10(-14), 10(-11), 10(-5) mol/kg) caused changes in kinetic parameters Vmax, Km of LDG and microviscosity in various ranges of microsomal membranes of brain cells. It is suggested that the effect of phenozan on the structure of bilayer membrane is important for binding LDG with membranes.

In paper the new aspects of action regularity of ionizing radiation of low intensity on the biophysical and biochemical characteristics of bio-objects and populations are considered. From the point of view of breaking the connection between occurrence of damages and work of systems of restoration at low intensity irradiation, are described the dose dependence of different types--from threshold up to extreme and a plateau curve, differing among themselves only by a parity of these processes. The features of action of low intensity irradiation on bio-objects and populations--change of structure of a population, sensitivity to action of external stimulus, force of connections between the elements of regulatory systems--allow to consider the low intensity irradiation as the factor capable to cause unpredictable transition of quasistationary systems in new status.

Biochemical, biophysical and functional properties of the genetic and membrane apparatus of the cell were considered activity and regulatory properties of the membrane and cytosolic enzymes of organs and tissues of mice exposed to radiation in the wide range of doses of 6 to 1800 mGy with the radiation intensity of 4.1 x 10(-3) and 41 x 10(-3) mGy/min. It was shown that the dose-dependence of changes in the investigated properties is of non-linear polymodal (bimodal) nature. The value of the maximum and the dose at which the latter was observed depend on the object's nature, radiation intensity and time passed after irradiation. An essential factor is that sensitivity of molecules, cells, organs and animals exposed to low-dose radiation to other damaging effects changes. The explanation is given in terms of the changes in the relation between the quantity of damages and the activity of reparation systems induced by low-dose irradiation.

The complex study on the low gamma-irradiation on the structural feature of lymphocyte DNA and lipid peroxidation (LPO) regulatory system parameters in mice blood was carried out depending on irradiation intensity. It was found that DNA alkaline elution rate constants, viscosity of the different regions of erythrocyte membranes and LPO products content in mice blood plasma varied nonlinearly depending on dose or dose rate. The proportion of the damage types and the range of the DNA structural changes substantially differ depending on the gamma-irradiation dose and its intensity. It is considered that the proportion of the DNA and membrane damage and repair can change depending on radiation dose and dose rate.