MIL-therapy / Method of treatment / 1. Mechanism of biological and therapeutic action produced by low-level IR radiation and light diodes.
1. Mechanism of biological and therapeutic action produced by low-level IR radiation and light diodes.
Laser application in medicine is based on the interaction of light with biologic tissues. Photobiologic effects directly depend on laser radiation parameters : wave length, intensity of light energy and time of exposure to biologic tissues (dose). IR LILR in the range of wavelength 0,85-1,3 mkm (thermal radiation) penetrates into biologic tissues as deep as 6-7 cm . The depth of penetration of this kind of radiation into tissues is defined as a distance for which the amplitude of electric field decreases by e times and the density decreases by e2 times (e=2,71 - the basement of natural logarithms). Comparatively powerful (1-10 Wt) and short (70-150 ns) impulses of IR LILR make tissues of biologic objects more transparent for low intensive (10-100 mWt) continuous IR LED radiation due to the effect of saturation electronic state population in the atom capsules of biologic tissues.
IR radiation is absorbed by oxygen, water, several enzymes and biologic structures (first of all, by cell membranes). Heat increases oscillatory energy in biomolecules and is utilised by the organism fluids. The absorption of light energy is a key moment on which the intensity of further processes depends. The basic law of photobiology says that biological effects may be caused only by the light with such wave length which is absorbed by separate molecules-acceptors or cellular membranes. Uneven LILR distribution and light absorption in different structures cause heat unbalance in biological tissues. It may lead to the deformation of cellular membranes ( due to changes in the osmotic pressure) and to changes in their electric potential which consequently effect the metabolic processes and is one of LILR biophysical, trigger mechanisms.
LILR with the wavelength from 0,9 to 1,3 mkm directly generates highly energetic singlete (excited) oxygen without any photosensitizers participation. The latter effecting cellular membranes changes tissural antigen features, leads to structural changes in a number of compounds including those with double chemical bonds - its acceptors ( purin and pirimidin basements, cholesterol, steroid and sex hormones, bile pigments, porfirins, etc.) and aliphatic compounds (fatty non-saturated, phospholipids, sphyngomielin, cerebrosides). It is quite obvious, that the character of oxidative-reductive reactions strictly depends on the concentration of singlet oxygen; hence, on the dose of laser effect. Laser pulses periodically, with definite frequency activate the above-mentioned process ( so-called “trigger principle”) and “feed” catalytic biochemical reactions with energy if some local energy misbalance occurs, for example, in any pathology.
Formation and transformation of labile products of photobiological process developing in tissues (such as free radicals, ion-radicals of oxidated and reduced forms, peroxides and other substances) occupies a comparatively short period of time but this period is extremely important for further development of biochemical and physiological reactions. As a result, the intensity of oxidative-reductive and biosynthetic processes is changed, metabolic processes in biological tissues are normalised, blood and lymph circulation is restored due to the dilatation of functioning capillaries and due to the opening of new ones. After several MIL-therapy sessions one can see the increased net of capillary system because of the growth of new capillaries (neovasculogenesis).
This multistage process may be presented in the following way: light quantum absorption => primary photophysical act => intermediate stages including the formation of photosensitized products in tissues or the transportation of energy on cell membrane components => triggering neurohumoral reactions => the final biological effect.
Response of a biological object to LILR impact at cellular and tissue level and adequate changes in the neurohumoral regulatory link form the final result of photobiological process developing through the mechanisms of urgent adaptation in the organism. Links defining this process frequently respond to the instant local situation developing under a pathologic process but, not because of the photobiological effect itself. Hereof comes a relative simplicity and fewness of the primary photobiophysical acts in the organism, but various and multiformed responsive reactions different by their secondary manifestations and final results.
Light is a main physical factor which supplies life on the Earth. LILR impacts bioobjects with therapeutic doses which do not cause any pathologic changes in cells; so, such radiation could be estimated as an adequate physiological irritant - signals which cause changes in natural physical-chemical, biophysical, biochemical and physiological processes. It gives a possibility to interfere with the course of a pathologic process at its any stage and to achieve a staged and consecutive restoration of the homeostatic balance.