Petukhov V.I., Shchukov A.N.
ABOUT THE JUSTIFIABILITY OF THE ELEMENTAL ANALYSIS DATA EXTRAPOLATION OF THE HUMAN HAIR TO THE TOTAL BODY ^{[№ 6 ' 2015]}
In recent years, the method of quantitative atomic emission spectrometry of bio-substrates such as human hair has become very popular in determination of person's elemental status. However, in recent publications on the topic questions about the relationship between elemental hair composition and the total body mineral content has been raised and requires special discussion. This article contents an attempt of such discussion. According to atomic emission spectrometry data, concentration values of chemical elements (including but not limited to metals), which are contained in hair, show expressed individual variation. This very fact suggests that the observed shifts may be caused not nearly by 'hypo- or hyperelementosis' but by redistribution of chemical elements mediated by intra- and extracellular regulators of transmembrane mineral traffic which has practically no effect on the total body elemental composition. There are many factors to be considered in determining the most probable causes of quantitative shifts in metal-ligand homeostasis (MLH). Their distinguishing feature is the capacity of activation or deactivation (up to a total block) of ionic channels — hydrous pores of transmembrane proteins, which are in charge of metals transfer. Activation of ligand-activated channels may take place due to redox-modification of thiol groups of cysteine in the molecule of proteins-transporters. Among the latter ones is the P-type ATPases superfamily, which ensures the transportation of not just electrogenic (Ca, Na, K) but also heavy metals (Cd, Zn, Pb, Cu, Co). Active oxygen species (AOS) and active nitrogen species (АNS), which are constantly formed in cells, fulfil the function of redox-modifiers of cysteine residues in the molecule of membrane pumps (oxidation with formation of disulphide bonds, S-nitrosylation). Having said this, one cannot exclude that increased production of AOS and АNS (oxidative/nitrosative stress) which may cause further activation of P-type ATPases. Therefore, in the setting of oxidative/nitrosative stress, we may expect quantitative shifts in intracellular concentrations of not just electrogenic but also heavy metals (transfer of the latter is affected by P1B-type-pump from the superfamily of ATPases). Does it mean that hair is not a very "reliable" substrate for MLH evaluation? Answering this question, it is necessary to notice that the problem is not with the substrate but with interpretation of metal-ligand homeostasis' variations in epidermal cells meter mined by spectrometry.