About some concept in aerospace medicine

R.A.Gareyev

Institute of human and animal physiology

The fact of adsorption of substances on erythrocyte surface was known in the twenties of the last century. In half a century it was concluded that protein adsorption on erythrocytes affects deformability of red blood cells and rheology of whole blood. Substances adsorbed on erythrocyte surface were considered as a reserve for their emergency supply to plasma.

"The main law of lymphology" also existed in the 20^th century according to which plasmic proteins got from blood to interstitial space return to blood flow solely through lymphatic vessels. The law was based on appearance of edema caused by lymph outflow blockage. Therewith difference in content of plasmic protein (DPP) between arteries and veins always means its outlet from blood to tissues.

After thorough examination we have found out that DPP defined by protein content in plasma does not allow for significant adsorption of protein on arterial and venous erythrocyte surface. Allowing for protein on the whole (adsorbed, endoglobular, plasmic), its transcapillary balance approaches the index of protein lymphatic transport by lymph. A hypothesis emerged that substances adsorbed on erythrocyte surfaces are transferred into near wall layer of blood capillaries and in the first place are involved into transcapillary exchange, participate in tissue metabolism and partially join the lymph.

New stage in studies of substances transportation by erythrocytes was caused by revealed fact that glucose transport on erythrocyte surfaces increased manifold in cosmonauts' blood at the day of landing.

Further we show that substance transportation by erythrocytes is a changeable and adjustable process, and glucose and lipids substantially exceed protein in the number of molecules adsorbed on erythrocytes. Adsorption of substances on erythrocytes depends on qualitative and quantitative indexes of hemoglobin of red blood cells. Known data and our results were generalized according to corresponding concept of absorptive-transporting function of erythrocytes. The name is given by analogy with gas-transport function of erythrocytes. Basing on diversified research the data appeared that absorption-desorption of substances on erythrocytes is an important component of many processes.

Having received a powerful incentive for research, absorption-transport function of erythrocytes itself has already created promising preconditions to its study in aspects of aerospace medicine (problem of edema, testing of biochemical adaptability, etc.). Thus transport of substances on erythrocytes' surface should be studied to the same extent as the problem of transport of substances in plasma.

Considering anti-edematous mechanism it is necessary to note, that it is amplified with known increase of amount of erythrocytes (and accordingly adsorption area) at their saturation by carbonic gas. Glucose recycling and erythrocytes saturation with carbonic gas are directly connected with energy metabolism. Concept of protein return from interstice to blood does not contradict known data on edemas frequently arising during diabetes, hypothyroidism, hypoproteinemia, anemia, and other pathologies, when level of protein adsorption on erythrocytes' surface and energy metabolism decrease. The above-stated mechanism should be taken into account when substantiating the actions reducing cosmonauts' regional tissue edemas.

By parameters of substances transportation on erythrocytes' surface one can also judge potential opportunities for metabolism enhancement (first of all, energy metabolism). Low glucose and lipids transport on erythrocytes of blood taken "on an empty stomach" indicates great potential for amplification of substances transportation, amplification of selective transfer of the most important substances. The higher is this potential, the more effectively it can be used during adaptation, in immunological processes etc.

On the whole, all the aforesaid to some extent is substantiation for conclusion that study of cosmonauts' blood system also requires analysis of substances transferred in blood on erythrocytes' surface.