Red blood cells: functions, norms of quantity in the blood, causes of deviations. Modern problems of science and education Carbonic anhydrase functions

The purpose of the work is to determine the factors influencing the activity of zinc-containing carbonic anhydrase in the reproductive system of male rats under conditions of exposure to low-intensity microwave radiation. Carbonic anhydrase plays an important role in the metabolism of seminal plasma and sperm maturation. Carbonic anhydrase activity in water-salt extracts of epididymis and testes of rats in the control group, according to our data, ranges from 84.0 ± 74.5 U/ml, which in terms of tissue weight is 336.0 ± 298.0 U/mg. The relationship between the concentration of zinc and polyamine ions and the activity of carbonic anhydrase was studied. The activity of carbonic anhydrase in the reproductive system of male rats has a complex regulation scheme, which obviously is not limited to the factors we have described. Based on the results obtained, it can be concluded that the role of various regulators of the activity of this enzyme varies depending on the degree of carbonic anhydrase activity. It is likely that high spermine concentrations limit the transcription of the carbonic anhydrase gene, given the data on the functions of this polyamine. Spermidine probably serves as a limiting factor at the post-tribosomal stages of regulation of carbonic anhydrase activity, and putrescine and the concentration of zinc ions are interrelated activation factors.

reproductive system of male rats

zinc ion concentration

polyamines

carbonic anhydrase

1. Boyko O.V. Methodological aspects of the use of hydrochloric acid spermine and spermidine for the identification of uropathogenic microflora / O.V. Boyko, A.A. Terentyev, A.A. Nikolaev // Problems of reproduction. – 2010. – No. 3. – P. 77-79.

2. Ilyina O.S. Changes in the zinc content in human blood in type I diabetes mellitus and features of the hypoglycemic effect of the zinc-containing insulin-chondroitin sulfate complex: abstract. dis. ...cand. biol. Sci. – Ufa, 2012. – 24 p.

3. Lutsky D.L. Protein spectrum of ejaculates of different fertility / D.L. Lutsky, A.A. Nikolaev, L.V. Lozhkina // Urology. – 1998. – No. 2. – P. 48-52.

4. Nikolaev A.A. Activity of spermoplasmic enzymes in ejaculates of different fertility / A.A. Nikolaev, D.L. Lutsky, V.A. Bochanovsky, L.V. Lozhkina // Urology. – 1997. – No. 5. – P. 35.

5. Ploskonos M.V. Determination of polyamines in various biological objects / M.V. Ploskonos, A.A. Nikolaev, A.A. Nikolaev // Astrakhan State. honey. acad. – Astrakhan, 2007. – 118 p.

6. Polunin A.I. The use of zinc in the treatment of male subfertility / A.I. Polunin, V.M. Miroshnikov, A.A. Nikolaev, V.V. Dumchenko, D.L. Lutsky // Microelements in medicine. – 2001. – T. 2. – No. 4. – P. 44-46.

7. Haggis G.C., Gortos K. Carbonic anhydrase activity of the reproductive tract tissues of male rats and its relationship to semen production // J. Fert. Reprod. – 2014. - V. 103. - P. 125-130.

It is known that the activity of zinc-containing carbonic anhydrase is high in the reproductive system of male birds, mammals and humans. The activity of this enzyme influences the maturation of sperm, their number and sperm volume. But there is no information about changes in carbonic anhydrase activity under the influence of other constant components of the reproductive system, such as zinc ions and polyamines (putrescine, spermine and spermidine), which actively influence spermatogenesis. Only a general description of the consequences of changes in carbonic anhydrase activity on the morphofunctional state of the organs of the reproductive system of male rats, the number of sperm, and their motility is given.

The purpose of our work was a study of the activity of zinc-containing carbonic anhydrase and its relationship with the level of polyamines and zinc ions in the tissue of the reproductive system of sexually mature male rats.

Materials and methods. The experimental part of the study included 418 male white Wistar rats. The rats were 6-7 months old (mature individuals). The body weight of the rats was 180-240 g, kept under standard vivarium conditions. To avoid the influence of seasonal differences in responses to experimental influences, all studies were carried out in the autumn-winter period of the year. The collection of testes and epididymis from rats was carried out under ether anesthesia (experimental studies were carried out in strict accordance with the Declaration of Helsinki on the Humane Treatment of Animals).

The objects of our study were water-salt extracts of epididymis and testes of sexually mature male white rats. Extracts were prepared in Tris-hydrochloric acid buffer pH = 7.6 in a weight/volume ratio of 1/5, after four times freezing, thawing and centrifugation at 8000 g for 50 minutes, the samples were frozen and stored at -24 °C until the study.

Determination of zinc. To 2 ml of the extract under study, 0.1 ml of 10% NaOH and 0.2 ml of a 1% solution of dithizone in carbon tetrachloride were added. In the negative control, 2 ml of distilled water was added, in the positive control - 2 ml of a 20 μmol zinc sulfate solution (molar concentration of a standard zinc sulfate solution). Samples were photometered at 535 nm. The concentration of zinc cations in the sample was calculated using the formula: CZn=20 µmol × Sample OD535/Standard OD535, where Sample OD535 is the optical density of the sample, measured at 535 nm; OD535 Standard - optical density of a standard 20 micromolar solution of zinc sulfate, measured at 535 nm.

Determination of carbonic anhydrase. The method is based on the reaction of bicarbonate dehydration with the removal of carbon dioxide formed as a result of dehydration with intensive bubbling of the reaction medium with air freed from carbon monoxide and simultaneous recording of the rate of change in pH. The reaction is initiated by quickly introducing a solution of the substrate - sodium bicarbonate (10 mM) into the reaction mixture containing the test sample. In this case, the pH increases by 0.01-0.05 units. Samples (10.0-50.0 mg) of epididymis and testes of sexually mature male white rats were homogenized and centrifuged at 4500 g for 30 minutes. at 4 °C, and the supernatant is diluted with double distilled water at 4 °C to a volume that would allow the reaction time to be measured. Carbonic anhydrase activity is determined by the change in the initial pH value from 8.2 to 8.7 in the CO2 dehydration reaction. The rate of accumulation of hydroxyl ions is measured electrometrically using a sensitive programmable pH meter (InoLab pH 7310) interfaced with a PC. The pH shift from 8.2 to 8.7, as a function of time in the linear section, takes into account the enzyme activity. The average time (T) for 4 measurements was calculated. The time of pH change during spontaneous hydration of CO2 in a medium without a sample was taken as control. Carbonic anhydrase activity was expressed in enzyme units (U) per mg of wet tissue according to the equation: ED = 2 (T0 - T)/ (T0 × mg tissue in the reaction mixture), where T0 = average time for 4 measurements of a pure solution of 4 ml of cooled, saturated carbon dioxide, bidistilled water.

Determination of polyamines. Samples (100–200 mg) of epididymis and testes of mature male albino rats were homogenized, suspended in 1 ml of 0.2 normal perchloric acid to extract free polyamines, and centrifuged. To 100 μl of the supernatant, 110 μl of 1.5 M sodium carbonate and 200 μl of dansyl chloride (7.5 mg/ml solution in acetone; Sigma, Munich, Germany) were added. In addition, 10 μL of 0.5 mM diaminohexane was added as an internal standard. After 1 h of incubation at 60°C in the dark, 50 μL of proline solution (100 mg/mL) was added to bind free dansyl chloride. Then dansyl derivatives of polyamines (hereinafter referred to as DNSC-polyamines) were extracted with toluene, sublimated in a vacuum evaporator and dissolved in methanol. Chromatography was performed on a reverse phase LC 18 column (Supelco), in a high performance liquid chromatography system (Dionex) consisting of a gradient mixer (model P 580), an automatic injector (ASI 100) and a fluorescence detector (RF 2000). Polyamines were eluted in a linear gradient from 70% to 100% (v/v) methanol in water at a flow rate of 1 mL/min and detected at an excitation wavelength of 365 nm and an emission wavelength of 510 nm. Data were analyzed using Dionex Chromeleon software and quantification was performed with calibration curves obtained from a mixture of pure substances (Figure A).

High performance chromatography of DNSC polyamines:

A - chromatogram of a standard mixture of DNSC-polyamines; B - chromatogram of DNSC-polyamines from one of the tissue samples of the epididymis and testes of male rats. 1 - putrescine; 2 - cadaverine; 3 - hexanediamine (internal standard); 4 - spermidine; 5 - sperm. The x-axis is time in minutes, the y-axis is fluorescence. Unnumbered peaks - unidentified impurities

Research results and discussion. As is known, carbonic anhydrase plays an important role in the metabolism of seminal plasma and sperm maturation. Carbonic anhydrase activity in water-salt extracts of epididymis and testes of rats in the control group, according to our data, ranges from 84.0 ± 74.5 U/ml, which in terms of tissue weight is 336.0 ± 298.0 U/mg. Such a high activity of the enzyme can be explained by its important physiological role. For comparison, the level of activity of this enzyme in other tissues of the same animals is much lower (Table 1), except for whole blood, in which high activity of erythrocyte carbonic anhydrase is known. However, what is noteworthy is the very wide scatter in the values ​​of carbonic anhydrase activity in epididymis and testes, the coefficient of variation of which is more than 150% (Table 1).

Table 1

Carbonic anhydrase activity in tissues of sexually mature males

This indicates the influence of unaccounted factors on the enzyme activity. There are two circumstances that explain this feature. Firstly, it is known that biologically active amines, including the polyamines spermidine and spermine, are capable of activating carbonic anhydrase. It is the male reproductive system that is the richest source of spermine and spermidine. Therefore, we carried out a parallel determination of the concentration of polyamines in water-salt extracts of epididymis and testes of male rats. The polyamines spermidine, spermine, and putrescine were analyzed by HPLC as described in Methods. It was shown that spermine, spermidine and putrescine were detected in the tissue of the epididymis and testes of male rats (Fig. B).

In healthy sexually mature male rats, the level of spermine was 5.962±4.0.91 µg/g tissue, spermidine 3.037±3.32 µg/g tissue, putrescine 2.678±1.82 µg/g tissue, and spermine/spermidine ratio 1.88- 2.91. Moreover, according to our data, both the level of spermidine and the level of spermine (to a lesser extent) are subject to significant fluctuations. Correlation analysis showed a significant positive relationship (r=+0.3) between the levels of spermine and spermidine, and, respectively, spermidine and putrescine (r=+0.42). Apparently, this circumstance is one of the factors influencing the high dispersion of the results of determining carbonic anhydrase activity.

Another regulator of carbonic anhydrase activity may be the level of zinc in the reproductive tissue of sexually mature male rats. According to our data, the level of zinc ion varies widely, from 3.2 to 36.7 μg/g of tissue of the total preparation of the testes and epididymis of sexually mature male rats.

Correlation analysis of zinc levels with levels of spermine, spermidine and carbonic anhydrase activity showed different levels of positive correlation between the concentration of zinc ions and these metabolites. An insignificant level of association was found with spermine (+0.14). Given the number of observations used, this correlation is not significant (p≥0.1). A significant positive correlation was found between the level of zinc ions and the concentration of putrescine (+0.42) and the concentration of spermidine (+0.39). An expectedly high positive correlation (+0.63) was also found between the concentration of zinc ions and carbonic anhydrase activity.

At the next stage, we tried to combine the concentration of zinc and the level of polyamines as factors regulating carbonic anhydrase activity. When analyzing the variation series of the joint determination of the concentration of zinc ions, polyamines and carbonic anhydrase activity, some regularities were revealed. It was shown that out of 69 studies conducted on the level of carbonic anhydrase activity, three groups can be distinguished:

Group 1 - high activity from 435 to 372 units (number of observations 37),

Group 2 - low activity from 291 to 216 units (number of observations 17),

Group 3 - very low activity from 177 to 143 units (number of observations 15).

When ranking the levels of polyamines and the concentration of zinc ions with these groups, an interesting feature was revealed that did not appear when analyzing the variation series. The maximum spermine concentrations (on average 9.881±0.647 μg/g tissue) are associated with the third group of observations with very low carbonic anhydrase activity, and the minimum (on average 2.615±1.130 μg/g tissue) with the second group with low enzyme activity.

The largest number of observations is associated with the first group with a high level of carbonic anhydrase activity; in this group, spermine concentrations are close to average values ​​(on average 4.675 ± 0.725 μg/g of tissue).

The concentration of zinc ions exhibits a complex relationship with the activity of carbonic anhydrase. In the first group of carbonic anhydrase activity (Table 2), the concentration of zinc ions is also higher than the values ​​in other groups (on average 14.11±7.25 μg/g of tissue). Further, the concentration of zinc ions decreases in accordance with the decrease in carbonic anhydrase activity, but this decrease is not proportional. If in the second group the activity of carbonic anhydrase decreases compared to the first by 49.6% and in the third by 60.35%, then the concentration of zinc ions decreases in the second group by 23%, and in the third by 39%.

table 2

The relationship between the concentration of polyamines and zinc ions and the activity of carbonic anhydrase

This indicates additional factors influencing the activity of this enzyme. The dynamics of putrescine concentration looks somewhat different (Table 2). The level of this polyamine is falling at a faster pace, and in the third comparison group the level of putrescine is lower on average by almost 74%. The dynamics of spermidine levels differ in that the “popping up” concentration values ​​of this polyamine are associated primarily with the second group of carbonic anhydrase activity levels. With high activity of this enzyme (group 1), the spermidine concentration is slightly higher than the average for all observations, and in the third group it is almost 4 times lower than the concentration in the second group.

Thus, the activity of carbonic anhydrase in the reproductive system of male rats has a complex regulation scheme, which obviously is not limited to the factors we have described. Based on the results obtained, it can be concluded that the role of various regulators of the activity of this enzyme varies depending on the degree of carbonic anhydrase activity. It is likely that high spermine concentrations limit the transcription of the carbonic anhydrase gene, given the data on the functions of this polyamine. Spermidine probably serves as a limiting factor at the post-tribosomal stages of regulation of carbonic anhydrase activity, and putrescine and the concentration of zinc ions are interrelated activation factors.

Under these conditions, assessing the influence of external factors (including those changing reproductive function) on the activity of carbonic anhydrase, as one of the important links in the metabolism of the reproductive system of male mammals, becomes not only important, but also a rather complex process, requiring a large number of controls and multilateral assessment.

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Which, paradoxically, are not independently used as diuretics (diuretics). Carbonic anhydrase inhibitors are mainly used for glaucoma.

Carbonic anhydrase in the epithelium of the proximal tubules of the nephron catalyzes the dehydration of carbonic acid, which is a key link in the reabsorption of bicarbonates. When carbonic anhydrase inhibitors act, sodium bicarbonate is not reabsorbed, but is excreted in the urine (urine becomes alkaline). Following sodium, potassium and water are excreted from the body in the urine. The diuretic effect of substances in this group is weak, since almost all of the sodium released into the urine in the proximal tubules is retained in the distal parts of the nephron. That's why Carbonic anhydrase inhibitors are currently not used independently as diuretics..

Carbonic anhydrase inhibitor drugs

Acetazolamide

(diacarb) is the most famous representative of this group of diuretics. It is well absorbed from the gastrointestinal tract and, unchanged, is quickly excreted in the urine (that is, its effect is short-term). Drugs similar to acetazolamide - dichlorphenamide(daranid) and methazolamide(neptazane).

Methazolamide also belongs to the class of carbonic anhydrase inhibitors. Has a longer half-life than acetazolamide and is less nephrotoxic.

Dorzolamide. Indicated for the reduction of elevated intraocular pressure in patients with open-angle glaucoma or ocular hypertension who are insufficiently responsive to beta-blockers.

Brinzolamide(trade names Azopt, Alcon Laboratories, Inc, Befardin Fardi MEDICALS) also belongs to the class of carbonic anhydrase inhibitors. Used to reduce intraocular pressure in patients with open-angle glaucoma or ocular hypertension. The combination of brinzolamide and timolol is actively used on the market under the trade name Azarga.

Side effects

Carbonic anhydrase inhibitors have the following main side effects:

• hypokalemia;
• hyperchloremic metabolic acidosis;
• phosphaturia;
• hypercalciuria with risk of kidney stones;
• neurotoxicity (paresthesia and drowsiness);
• allergic reactions.

Contraindications

Acetazolamide, like other carbonic anhydrase inhibitors, is contraindicated in cirrhosis of the liver, since alkalinization of the urine prevents the release of ammonia, which leads to encephalopathy.

Indications for use

Carbonic anhydrase inhibitors are primarily used to treat glaucoma. They can also be used to treat epilepsy and acute mountain sickness. Since they promote the dissolution and elimination of uric acid, they can be used in the treatment of gout.

Acetazolamide used in the following conditions:

• Glaucoma (reduces the production of intraocular fluid by the choroid plexus of the ciliary body.
• Treatment of epilepsy (petit mal). Acetazolamide is effective in treating most types of seizures, including tonic-clonic and absence seizures, although it has limited benefit as tolerance develops with long-term use.
• For the prevention of nephropathy during treatment, since the breakdown of cells releases a large amount of purine bases, which provide a sharp increase in the synthesis of uric acid. Alkalinization of urine with acetazolamide due to the release of bicarbonates inhibits nephropathy due to the loss of uric acid crystals.
• To increase diuresis during edema and correct metabolic hypochloremic alkalosis in CHF. By reducing the reabsorption of NaCl and bicarbonates in the proximal tubules.

However, for none of these indications is acetazolamide the primary pharmacological treatment (drug of choice). Acetazolamide is also prescribed for mountain sickness (as it causes acidosis, which leads to the restoration of the sensitivity of the respiratory center to hypoxia).

Carbonic anhydrase inhibitors in the treatment of mountain sickness

At high altitudes, the partial pressure of oxygen is lower, and people must breathe faster to get enough oxygen to live. When this happens, the partial pressure of carbon dioxide CO2 in the lungs is reduced (simply blown out when you exhale), resulting in respiratory alkalosis. This process is usually compensated by the kidneys through bicarbonate excretion and thereby causes compensatory metabolic acidosis, but this mechanism takes several days.

More immediate treatment is carbonic anhydrase inhibitors, which prevent bicarbonate uptake in the kidneys and help correct alkalosis. Carbonic anhydrase inhibitors also improve chronic mountain sickness.

The first school lessons about the structure of the human body introduce the main “inhabitants of the blood: red cells - erythrocytes (Er, RBC), which determine the color due to the content they contain, and white cells (leukocytes), the presence of which is not visible to the eye, since they are colored do not influence.

Human red blood cells, unlike animals, do not have a nucleus, but before losing it, they must go from the erythroblast cell, where the synthesis of hemoglobin just begins, to reach the last nuclear stage - which accumulates hemoglobin, and turn into a mature nuclear-free cell, the main a component of which is red blood pigment.

What people have not done with red blood cells, studying their properties: they tried to wrap them around the globe (4 times), and put them in coin columns (52 thousand kilometers), and compare the area of ​​red blood cells with the surface area of ​​the human body (red blood cells exceeded all expectations , their area turned out to be 1.5 thousand times higher).

These unique cells...

Another important feature of red blood cells is their biconcave shape, but if they were spherical, then their total surface area would be 20% less than the real one. However, the abilities of red blood cells lie not only in the size of their total area. Thanks to the biconcave disc shape:

1. Red blood cells are able to carry more oxygen and carbon dioxide;
2. Show plasticity and freely pass through narrow openings and curved capillary vessels, that is, there are practically no obstacles for young, full-fledged cells in the bloodstream. The ability to penetrate into the most remote corners of the body is lost with the age of red blood cells, as well as in their pathological conditions, when their shape and size change. For example, spherocytes, sickle-shaped, weights and pears (poikilocytosis) do not have such high plasticity, macrocytes, and even more so megalocytes (anisocytosis), cannot penetrate into narrow capillaries, therefore the modified cells do not perform their tasks so flawlessly.

The chemical composition of Er is represented largely by water (60%) and dry residue (40%), in which 90 - 95% is occupied by red blood pigment -, and the remaining 5 - 10% are distributed between lipids (cholesterol, lecithin, cephalin), proteins, carbohydrates, salts (potassium, sodium, copper, iron, zinc) and, of course, enzymes (carbonic anhydrase, cholinesterase, glycolytic, etc.).

Cellular structures that we are accustomed to noticing in other cells (nucleus, chromosomes, vacuoles) are absent in Er as unnecessary. Red blood cells live for up to 3 - 3.5 months, then they age and, with the help of erythropoietic factors that are released when the cell is destroyed, give the command that it is time to replace them with new ones - young and healthy.

The erythrocyte originates from its predecessors, which, in turn, originate from a stem cell. If everything is normal in the body, red blood cells are reproduced in the bone marrow of flat bones (skull, spine, sternum, ribs, pelvic bones). In cases where, for some reason, the bone marrow cannot produce them (tumor damage), red blood cells “remember” that other organs (liver, thymus, spleen) were engaged in this during intrauterine development and force the body to begin erythropoiesis in forgotten places.

How many should there be normally?

The total number of red blood cells contained in the body as a whole and the concentration of red cells coursing through the bloodstream are different concepts. The total number includes cells that have not yet left the bone marrow, have gone into storage in case of unforeseen circumstances, or have set sail to perform their immediate duties. The totality of all three populations of red blood cells is called - erythron. Erythron contains from 25 x 10 12 /l (Tera/liter) to 30 x 10 12 /l red blood cells.

The norm of red blood cells in the blood of adults differs by gender, and in children depending on age. Thus:

• The norm for women ranges from 3.8 - 4.5 x 10 12 / l, respectively, they also have less hemoglobin;
• What is a normal indicator for a woman is called mild anemia in men, since the lower and upper limits of the norm for red blood cells are noticeably higher: 4.4 x 5.0 x 10 12 / l (the same applies to hemoglobin);
• In children under one year old, the concentration of red blood cells is constantly changing, so for each month (for newborns - each day) there is its own norm. And if suddenly in a blood test the red blood cells in a two-week-old child are increased to 6.6 x 10 12 / l, then this cannot be regarded as a pathology, it’s just that this is the norm for newborns (4.0 - 6.6 x 10 12 / l).
• Some fluctuations are observed after a year of life, but normal values ​​are not very different from those in adults. In adolescents aged 12-13 years, the hemoglobin content in red blood cells and the level of red blood cells themselves correspond to the norm for adults.

An increased amount of red blood cells in the blood is called erythrocytosis, which can be absolute (true) and redistributive. Redistributive erythrocytosis is not a pathology and occurs when red blood cells are elevated under certain circumstances:

1. Stay in mountainous areas;
2. Active physical labor and sports;
3. Psycho-emotional agitation;
4. Dehydration (loss of fluid from the body due to diarrhea, vomiting, etc.).

High levels of red blood cells in the blood are a sign of pathology and true erythrocytosis if they are the result of increased formation of red blood cells caused by unlimited proliferation (reproduction) of the precursor cell and its differentiation into mature forms of red blood cells ().

A decrease in the concentration of red blood cells is called erythropenia. It is observed with blood loss, inhibition of erythropoiesis, breakdown of red blood cells () under the influence of unfavorable factors. Low red blood cells and low red blood cell Hb levels are a sign.

What does the abbreviation mean?

Modern hematological analyzers, in addition to hemoglobin (HGB), low or high levels of red blood cells (RBC), (HCT) and other usual tests, can calculate other indicators, which are designated by a Latin abbreviation and are not at all clear to the reader:

In addition to all the listed advantages of red blood cells, I would like to note one more thing:

Red blood cells are considered a mirror that reflects the state of many organs. A kind of indicator that can “feel” problems or allows you to monitor the course of the pathological process is.

For a big ship, a long voyage

Why are red blood cells so important in diagnosing many pathological conditions? Their special role arises and is formed due to their unique capabilities, and so that the reader can imagine the true significance of red blood cells, we will try to list their responsibilities in the body.

Truly, The functional tasks of red blood cells are wide and diverse:

1. They transport oxygen to tissues (with the participation of hemoglobin).
2. They transfer carbon dioxide (with the participation, in addition to hemoglobin, of the enzyme carbonic anhydrase and the ion exchanger Cl- /HCO 3).
3. They perform a protective function, as they are able to adsorb harmful substances and transfer antibodies (immunoglobulins), components of the complementary system, formed immune complexes (At-Ag) on ​​their surface, and also synthesize an antibacterial substance called erythrin.
4. Participate in the exchange and regulation of water-salt balance.
5. Provide tissue nutrition (erythrocytes adsorb and transport amino acids).
6. Participate in maintaining information connections in the body through the transfer of macromolecules that provide these connections (creative function).
7. They contain thromboplastin, which is released from the cell when red blood cells are destroyed, which is a signal for the coagulation system to begin hypercoagulation and formation. In addition to thromboplastin, red blood cells carry heparin, which prevents thrombus formation. Thus, the active participation of red blood cells in the process of blood clotting is obvious.
8. Red blood cells are capable of suppressing high immunoreactivity (acting as suppressors), which can be used in the treatment of various tumor and autoimmune diseases.
9. They participate in the regulation of the production of new cells (erythropoiesis) by releasing erythropoietic factors from destroyed old red blood cells.

Red blood cells are destroyed mainly in the liver and spleen with the formation of breakdown products (iron). By the way, if we consider each cell separately, it will not be so red, but rather yellowish-red. Accumulating into huge masses of millions, they, thanks to the hemoglobin contained in them, become the way we are used to seeing them - a rich red color.

Video: Lesson on Red Blood Cells and Blood Functions

I Carbonic anhydrase (synonym: carbonate dehydratase, carbonate hydrolyase)

an enzyme that catalyzes the reversible hydration reaction of carbon dioxide: CO 2 + H 2 O ⇔ H 2 CO 3 ⇔ H + + HCO 3. Contained in red blood cells, cells of the gastric mucosa, adrenal cortex, kidneys, and in small quantities in the central nervous system, pancreas and other organs. The role of acid in the body is associated with maintaining acid-base balance (acid-base balance) , transport of CO 2, formation of hydrochloric acid by the gastric mucosa. K.'s activity in the blood is normally quite constant, but in some pathological conditions it changes sharply. An increase in K.'s activity in the blood is observed in anemia of various origins, circulatory disorders of the II-III degree, some lung diseases (bronchiectasis, pneumosclerosis), as well as during pregnancy. A decrease in the activity of this enzyme in the blood occurs with acidosis of renal origin, hyperthyroidism. With intravascular hemolysis, K.'s activity appears in the urine, while normally it is absent. It is advisable to monitor K.’s activity in the blood during surgical interventions on the heart and lungs, because it can serve as an indicator of the body's adaptive capabilities, as well as during therapy with carbonic anhydrase inhibitors - hypothiazide, diacarb.

To determine K.'s activity, radiological, immunoelectrophoretic, colorimetric, and titrimetric methods are used. The determination is made in whole blood taken with heparin or in hemolyzed red blood cells. For clinical purposes, the most acceptable colorimetric methods for determining K activity (for example, modifications of the Brinkman method), based on establishing the time required to shift the pH of the incubation mixture from 9.0 to 6.3 as a result of CO 2 hydration. Water saturated with carbon dioxide is mixed with an indicator-buffer solution and a certain amount of blood serum (0.02 ml) or a suspension of hemolyzed erythrocytes. Phenol red is used as an indicator. As carbonic acid molecules dissociate, all new CO 2 molecules undergo enzymatic hydration. To obtain comparable results, the reaction should always proceed at the same temperature; it is most convenient to maintain the temperature of melting ice at 0°. The control reaction time (spontaneous reaction of CO 2 hydration) is normally 110-125 With. Normally, when determined by this method, K.’s activity is on average equal to 2-2.5 conventional units, and in terms of 1 million red blood cells, 0.458 ± 0.006 conventional units (a unit of K.’s activity is taken to be a 2-fold increase in the speed of the catalyzed reaction).

Bibliography: Clinical evaluation of laboratory tests, ed. WELL. Titsa, per. from English, p. 196, M., 1986.