Chemical antiradiation protection

Chemical antiradiation protection - introduction of certain chemical substances before or during exposure, in order to prevent or reduce the development of radiation damage. Chemical antiradiation protection possible by the fact that in the development of radiation damage has several stages. On the first stage of physical processes occur - ionization and excitation of molecules, which can interfere only means of physical protection (see). At the next stage can come directly modify sensitive elements cells (direct action), but much more often the so-called indirect effect. At the same time existing in all living cells water is split into ions H+ and Oh-, which in conditions of radiation form with oxygen several short-lived, but chemically very active compounds, under the influence them and be further chemical changes vital polyatomic molecules in the cell nucleus, such as DNA, some enzymes , etc., (such a path confirmed by the presence of oxygen effect, which is that when exposed to oxygen-poor environment action of x-ray and gamma radiation is attenuated). To prevent the development of further changes, and founded a chemical antiradiation protection. Among the many hundreds of tested substances found a number of compounds that when introducing them into the organism immediately prior to or shortly before exposure to a greater or lesser extent weaken the severity of subsequent radiation damage. This, for example, sulfur-containing amino acids and aminothiol [cysteine, glutathione, Marklin, aminoacylation (AET), and others], which are easily oxidized due to their composition sulfhydryl group -SH. Some do not contain sulfur amines (tryptamine, serotonin and others) also have a protective effect, especially when combined with the previous one. Antiradiation protection have substances that suppress tissue respiration.
A similar effect may determine stay during irradiation in an atmosphere with low oxygen content, mechanical circulatory disorders of separate parts of the body, such as a tourniquet on a limb. The mechanism of protective action of these funds is difficult and not all are the same, but it is based on the reduction of the contents or use of oxygen in tissues of irradiated organism.
Certain protective effect has a number of non-specific tools used in advance, such as vaccination a few weeks prior to exposure.
All specific chemical and pharmacological tools antiradiation protection United under the name "radioprotective agents", or radioprotectors (see).

Chemical (biological) antiradiation protection. The weakening of the radiation damage is achieved by the introduction into the body before exposure to ionizing radiation of certain compounds of various chemical forms. Currently there are several hundred protective remedies (protectors) and their combinations that have radioprotective effect. Chemical antiradiation protection normally classified based on their chemical properties. So, for example, distinguish the class of protectors - amination, serosoderzhashchikh amino acids, cyanophoric etc.
The peculiarities of action on an organism all means chemical antiradiation protection can be divided into two groups: 1) the means acting in a one-time; 2) means in effect the re-introductions. The first group includes those protectors that are injected into the body shortly before exposure once in doses that have a significant shift in physiological and biochemical processes in the body (aminothiol, Lanovoy and others). The second group includes some vitamins, hormones.
Chemical antiradiation protection of the first group, as a rule, be effective when irradiated animals in lethal doses. Funds antiradiation protection of the second group used when exposed to radiation in sublethal doses.
The mechanism of action of funds antiradiation protection of the first group is defined by the ability of these compounds to form a temporary connection with important biological macromolecules, temporary, local tissue hypoxia, to drastically change the course of all major biochemical radiosensitive reactions to exposure. The mechanism of action of antiradiation protection of the second group is related to the increase of the total radioresistance tissues, increasing strength of blood vessels, activation of blood processes, etc.
To the substances of the second group can be attributed, for example, the substances possessing properties of vitamin R (citrine, Maureen, hesperidin), ascorbic acid, a combination of vitamins P and Cider. There is evidence of radioprotective action of Biotin, thiamine (vitamin B1), vitamin B6, and B12, hormones estradiol, stilbestrol, adrenaline, etc.
Especially effective and promising combined use of funds antiradiation protection of the first and second groups. Of the many tools antiradiation protection in clinical practice in radiation therapy of cancer patients have found while using only a few protectors: beta-mercaptoethylamine (tsistamin, Marklin, bcaplan, Lambrate), disulfide form P-mercaptoethylamine (tsistamin), propain, aminoacylation and some other
Effective drugs antiradiation protection can be used to protect crews of spacecrafts in the conditions of radiation danger.
Antiradiation protection is widely used in radiobiological laboratories in the study of the primary mechanisms of action of ionizing radiation on the organism and mechanisms of action of protectors.
The search for new means of chemical antiradiation protection is conducted in many radiobiological laboratories of different countries.