Role of Red Blood Cells in Adaptive Changes in Fibrinolytic System of Young Men at One-Time Muscle Load

Фотографии: 

ˑ: 

M.V. Lapshina, associate professor, Ph.D.
O.S. Shubina, professor, Dr.Biol.
S.P. Golyshenkov, professor, Ph.D.
N.A. Mel'nikova, associate professor, Ph.D.
Mordovian State Pedagogical Institute named after M.E. Evsev'ev, Saransk

Keywords: physical load, lipid peroxidation, erythrocytes, fibrinolysis.

Introduction. During the past century, physiologists, who studied the hemostatic system, tried to determine the main principles of clotting and fibrinolytic responses to physical load. At the same time, it has been impossible to clearly imagine the totality of processes occurring in the tissues, cells and plasma, and resulting in the change of the blood hemostatic potential under physical load so far. Particularly, this is due to coagulation and fibrinolytic reactions to muscular activity being different in each individual person, which makes it hard to determine the peculiarities typical for the human population in general [2-10].

The purpose of the study was to determine the role of erythrocytes in adaptive changes in the blood fibrinolytic activity at single physical load.

Materials and methods. 30 apparently healthy young males - students of the faculty of physical culture (age 19.5 ± 0.16 years old, height 174.88 ± 1.14 cm, weight 69.79 ± 1.54 kg, PWC170 = 2.6 ± 0.08 W/kg), who performed a single 20-minute physical load on the veloergometer "Rhythm VE-05" at 2.23 ± 0.12 W/kg were involved in the study.

The blood samples were taken from the median cubital vein before the workout (after 15-20 minutes of rest in vitro) and after the load at the 1st minute of the recovery period. We determined natural clot lysis by the method of M.A. Kotovshchikova and B.I. Kuznik [6] and euglobulin clot lysis time [1] in all the subjects. In the first series of studies the euglobulin clot lysis time was determined in the presence of 0.02 ml of zero-dilute suspension of erythrocytes triple-washed in the isotonic sodium chloride solution. These erythrocytes were added to the reacting mixture upon dissolution of the cell pallet by the buffer. We tested the erythrocyte cell-free extract (ECFE) for methylenedioxyamphetamine (MDA) using the thiobarbituric acid test. In the second series we determined the euglobulin clot lysis time of the platelet-poor plasma after 20-min incubation of washed erythrocytes at t = 37ºC. Erythrocytes added 0.1 and 0.2 ml to the volume.

The activity of the specific erythrocyte-bound fibrinolytic agents was estimated by coating the heated and cold fibrin plates simultaneously with the intact erythrocyte suspensions, non-activated and activated by streptokinase and fibrinolysin.

The findings were processed by the methods of variation statistics using the Student's t-test.

Results and discussion. According to the results received during the first series, the blood fibrinolytic activity (fa) in response to physical load increased by 21.8% in all testees. Based on individual changes in the lytic potential of blood two types of response were singled out. The first type (n = 18) was characterized by stimulation of fibrinolysis in whole blood by 68.9%, the second one (n = 12) - by 33.9% retardation (Table 1). The euglobulin clot lysis time decreased significantly in all testees in general and in the groups of different response types.

We evaluated the FA of the red blood cells by their effect on the euglobulin clot lysis time of the platelet-poor plasma. We determined the ratio of the euglobulin clot lysis time to the similar index in the presence of erythrocytes (erythrocyte activity index). The index increment testified to the increase in FA.

Erythrocytes in the testees in the physiological rest position (erythrocytes at rest) reduced the euglobulin clot lysis time, that is, had a pronounced fibrinolytic activity. The load caused an increase in the lytic activity of erythrocytes in all subjects on the whole and in those of the first response type. In the second group no significant changes were detected in their activity. It can be assumed that these subjects had a decrease in the blood FA due to zero activization of the fibrinolytic potential of erythrocytes, as fibrinolysis in plasma was definitely intensified in all subjects and in the groups of both of the response types (by 28.5-29.7%).

There were no statistically significant changes in the level of MDA in ECFE in the whole sampling and in those of the second response type. This, however, does not mean that the rate of lipid peroxidation (LP) does not change with dynamic muscular activity. Apparently, this owes to the fact that, normally, generation and consumption of lipid peroxidation products are well-balanced in the body, and the systems regulating these processes are able to reset peroxidation to the initial level. A decay of MDA content by 22.5% at the first response type is of particular interest. We detected a correlation between the indices of plasma euglobulin fibrinolysis in the presence of erythrocytes and MDA concentration in the cell extract of the corresponding erythrocytes. According to the detected correlation, with the decrease in the level of MDA in the red blood cells, their fibrinolytic activity increases (r = 0.55622, p < 0.002).

Table 1. Impact of single physical load on fibrinolytic and LP indicators

Indicators

All testees

First response type

Second response type

rest

load

rest

load

rest

load

Fibrinolysis in whole blood, %

16.47

20.13

14.98

25.3***

18.7

12.37*

Euglobulin fibrinolysis, min

198.26

140.07***

192.44

135.13**

206.73

146.67***

Euglobulin fibrinolysis in plasma at rest with erythrocytes at rest and under load, min

167.14

158*

171.63

157.06**

161.17

159.25

MDA in ECFE, nM/g Hb

4.33

3.86

4.72

3.66*

3.7

4.18

Erythrocyte activity index, c.u.

1.18

 

1.26*

 

1.14

 

1.26**

 

1.24

 

1.27

 

 

Note. * – p < 0.05, ** – p < 0.01, *** – p < 0.001.

 The analysis of the fibrinolytic factors of erythrocytes, conducted using the fibrin plates (Table 2), revealed the presence of fibrinolytic factors within the cells.

Erythrocytes in the individuals from the second group were characterized by a slightly higher concentration of plasminogen activator and plasmin at rest, which explains their fibrinolytic hyperactivity.

Table  2. Activity of fibrinolytic system components in erythrocytes at rest and after muscular load

Indicators

All testees

First response type

Second response type

 

rest

load

rest

 

rest

load

Fibrinolytic system components, mm2:

 

 

 

 

 

 

activators

23.43

31.46

20.9

33.66*

26.41

33.45

proactivators

41.27

54.46

46.78

42.87

37.55

61.89

plasmin

21.10

33.00**

19.48

32.72**

23.52

33.42

plasminogen

44.53

37.87*

43.3

26.41**

43.34

43.3

antiplasmin

20.83

27.45

24.56

31.84

14.99

27.7

Strenuous work caused an increase in the level of plasminogen activators in the red blood cells. It is known that physical load or adrenalin injection increase the concentration of the given fibrinolytic factor in the blood. Such an effect of adrenalin is mediated through the body organs and tissues. Thus, under the influence of catecholamines, fibrinolytic activators are released by the vessel walls and endothelium of the heart, the kidney and intestinal tract tissues. Obviously, in this case erythrocytes, being correlated with the blood fibrinolytic activity, displayed their adsorbing capacity in relation to plasminogen activators.

A significant (by 56%) increase in plasmin concentration was caused by the load in all the subjects. Enzyme strength increase under load complied with a decrease in the concentration of its inactive antecedent - plasminogen (by 15%). Probably, under the influence of physical activity the plasminogen in the red blood cells partially transforms into an active enzyme.   

The changes in the proportion of the fibrinolytic system components were more pronounced in the subjects from the 1st group: increase of activators - by 61%, plasmin - by 68%, plasminogen level decrease - by 39%. In the 2nd group no significant changes were found in the activity of the above-listed factors. Along with the increase in the fibrinolytic activity of red blood cells, we traced rather a clear tendency to densification of antiplasmins, moreover, it was the most pronounced in the 2nd group.

Conclusions       

1. Human erythrocytes have strong fibrinolytic properties due to the content and activity of plasminogen activators, plasminogen proactivators, plasmin and antiplasmin in them.

2. High-intensity exercise causes individual multi-directional responses of the fibrinolytic system of the whole blood, which are caused largely by the specificity of erythrocyte responses. Erythrocytes respond to physical activity in two ways. The first is characterized by the increased adsorption activity of erythrocytes and their content of plasminogen activators and active plasmin with an adequate decrease in the plasminogen concentration. The second is the lack of response of amplification of adsorption and fibrinolytic activity with the antiplasmin content tending to increase.

3. The primary changes in the state of immediate adaptation occur at the level of cell membranes, including by modifying the lipid bilayer against the background of changes in the lipid peroxidation processes. Changes in the fibrinolytic activity of erythrocytes during muscular work are linearly correlated with the processes of lipid peroxidation of membranes. A decrease of the MDA level in red blood cells promotes an increase of their fibrinolytic activity.

4. It makes certain sense and value in the field of medicine and sports physiology to investigate the role of formed elements in adaptive reactions of the body. Knowing which factors determine the direction of the response of the hemostatic system to a stimulus, we can purposefully influence a person for him to acquire a better response. Working at these questions will greatly influence the objectiveness of evaluation of adaptation, regulation of protective functions and prevention of premorbid states in man when exercising and doing sports.

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Corresponding author:  mvlapshina@yandex.ru