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Based on the biochemical composition of erythrocyte membrane and asymmetric distribution of phospholipids, proteins, and cholesterol, FT-IR spectroscopy can monitor the distribution and interaction pattern of membrane constituents.The study series included 21 clinically healthy subjects aged between 20 and 60 years. Complete blood counts were performed and the serum biochemical compounds (cholesterol, triglycerides, total protein, glucose) were determined.The parameters that can be assessed by erythrocyte FT-IR in relation with the biochemical factors that may influence membrane fluidity are: degree of fatty acids unsaturation, saturated fatty acids/unsaturated fatty acids ratio, cholesterol/phospholipids ratio, and phospholipids/protein ratio. Based on the obtained results, in the assessment of membrane status the following vibration modes were selected as spectral parameters: vibration associated valence bond (=CH), asymmetric valence CH2 groups, modes associated with P=O bond and amine bands I and II specific for proteins. Other parameters, such as v(C-O) specific to glucose, may provide additional information on glucose metabolic status.By correlating biochemical markers with these spectral parameters information on red cell membrane status, status that may reflect different pathological processes, can be obtained.

Membrane fluidity is a complex parameter, influenced both through some biophysical (temperature, electrical charges, pH) and biochemical factors (protein/phospholipids ratio, phospholipids/cholesterol ratio, degree of fatty acids unsaturation). It is a parameter that reflects the main membrane characteristic organization (gel or liquid crystal structure). Experiments provide consistent data about membrane fluidity relations to various cellular processes, especially membrane processes. Passive transport is influenced directly by membrane lipid composition, and consequently, membrane fluidity, or by channels and carriers molecules interactions with adjacent membrane lipids. Membrane diffusion is related both to the hydrophobic nature of the particles and of the membrane environment. Depending on the mode of interaction with membrane proteins, lipids may be classified as non-annular lipids, annular and "mass" lipids. Different types of fatty acids affect the function of many channels, by stimulating or inhibiting them. These effects might be mediated through direct binding of the lipids to the channel or through indirect hydrophobic interactions. Active transport pumps conformation could be modulated, also, through interactions with adjacent lipids of the bilayer (especially cholesterol) and membrane micro-domains organization. In conclusion, membrane fluidity is close related both to passive and active transport.

The MDR character is a major factor that influence the effectiveness of cancer chemotherapy. This feature can be noninvasively evaluated through 99mTc isonitrils (MIBI, Tetrofosmin) scintigraphy, because these radiotracers cellular efflux is mediated by the Pgp membranar active transport system, the same that mediate chemotherapy drugs cellular efflux. The Pgp glycoprotein overexpression in the case of the MDR positive tumoral cells will determine both the chemotherapic drug and the isonitrile radiotracer quickly efflux from the cell. This paper present, based both on the literature and personal authors research work, the principle of the method, radiotracers structural characteristics and cellular uptake mechanism, practical protocol details from the acquisition untill the qualitative and quantitative image processing and results interpretation. Quantification indexes are proposed for the radiotracer cellular uptake quantitative evaluation on the scintigraphic image. The results could bring the possibility to make MDR positive patient diagnosis and further selection for the MDR modulators drug therapy.