In the course of our research the significant increasing of blood microcirculation both in the mucosa of the nasal cavity by direct blowing the nasal cavity by NO-containing gas flow and in the eardrum by blowing the skin of postauricular area was shown experimentally. The “placebo” experiment with the same airflow without NO confirmed that the stimulation of microcirculation occurred due to the action of NO (see here (in Russian only, sorry) Lapitan D.G., Rogatkin D.A. et. al. // Medical physics, No.1, 2012. – p. 61-68). Therefore it was interesting to understand purely theoretically: whether diffusion of NO-molecules into the skin and mucous membranes of bodies in the needed quantity during experiment is possible? The modeling was passed by a solution of the standard diffusive equation. The results of the theoretical modeling of the NO diffusion into the skin and mucosa of the nasal cavity showed that in the case of mucosa a diffusion of NO-molecules in the right quantity in the area of the microvasculature is possible within the limits of experimental conditions. But in the case of the postauricular skin a diffusion of NO does not increase the NO concentration at the depth of the skin’s microvessels in the right quantity to run the process of vasodilatation. Moreover, such increase of NO concentration cannot be in the eardrum at all. According to literature data the increase of NO in the 5-10 times in the tissue compared with the background concentration value of 10-5 mol/m3 is necessary for pronounced stimulation of the blood microcirculation. According to our results of the theoretical modeling in the case of mucosa of the nasal cavity such increase due to the diffusion can be achieved by blowing the mucous after 30 seconds when only 1% of NO molecules from the flow penetrates the mucosa. Thus the mechanism of stimulation of the microcirculation due to the direct diffusion of NO through the mucosa by blowing the nasal cavity is theoretically possible. But in the case of a skin a similar increase of NO concentration on the depth of the vessels is achieved only after a 1 minute and only under the condition when 30% of NO flow penetrates the horny layer of skin and only 70% of that is reflected, that seems to be not real. Moreover, here we are talking about the vessels of the skin rather than about the vessels of the eardrum. That is the amplification mechanism of microcirculation in the eardrum cannot be related with the direct diffusion of NO-molecules through the skin. 
     Since the results of the experiment showed the significant increasing of blood microcirculation in the eardrum of the subject precisely for NO but not for air it is not excluded that in this case the stimulation mechanism is realized due to inhalation by subject of NO molecules which are located in the surrounding air while working the device «Plason». Obviously in this case the amplification of the microcirculation must be systemic and be observed in all organism. For that it is necessary to inhale and acquire about 8×10-6 mol of NO at experiment that is theoretically possible at NO production by device «Plason» of 2,7×10-4 mol for 2 minutes of blowing in the used operating mode. Another version is a certain reflex mechanism for example due to the physical or chemical action of NO on skin receptors of postauricular area with the subsequent «targeted» generation of endogenous NO in the system of blood microcirculation of the eardrum. However we don`t know biophysics and biochemistry of such process. But it is possible to notice that what from two options specified by us it was not realized, both of them can result, finally, to increasing of concentration of NO in tissues and bodies that it is easily possible to take as a result of the direct diffusion of gases through the skin if not to use theoretical calculations. In one word, the identical experimentally fixed result can be realized via different mechanisms. The obtained results are critical for justification of application of a method of NO-therapy in clinical practice for the purpose of activation of regenerative processes at the patients who have transferred various operations including in the nasal cavity, paranasal sinuses and ear.

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