Blood Doping

From Chempedia

Blood doping is the practice of intravenously infusing blood into an athlete’s body to increase performance. The purpose of blood doping is to boost an individuals total aerobic power by increasing the amount of oxygen that is accessible to the working muscles. The method of blood doping is becoming increasingly popular for competitive athletes in endurance sports, such as cycling, cross-country skiing and long distance running. There are two main methods of blood doping: Autologous and Homologous.

Autologous blood doping is the process of removing ones own blood and reintroducing the blood back into the athletes body at a later date. Blood consists of 55 percent plasma, 45 percent erythrocytes (commonly called red blood cells) and one percent leukocytes and platelets. In an adult male there are five to six liters of blood in the circulatory system and about four to five liters in an adult female. About four to six weeks prior to competition, athletes remove about 450mL of blood. About an hour before a competition the erythrocytes are re-infused back into the blood, which causes the blood to undergo erythrocytosis. "Erythrocytosis is blood containing an abnormally large number of erythrocytes in the circulating blood."(2) By allowing more oxygen to reach the muscles at peak performance the athlete will not experience fatigue. Since autologous blood doping uses the athletes own blood, there is a decrease in athletic performance after donating. "It takes time for the body to recover from the loss of blood that occurs during donation. It would be hard to train effectively while having to donate a supply of blood sufficient to enhance performance." (3)

Homologous blood doping is a way for athletes to enhance their performance without compromising training time. Homologous blood doping involves the donation of blood from one person which is then transfused into another athletes body. There are major risks involved in this process, such as contracting blood born diseases and a potentially deadly transfusion reaction. In addition to this, the foreign blood is easier to detect through current testing methods, which will be discussed later in the article.

The main purpose of blood doping is to increase the oxygen to the muscles to enhance performance levels. This would not be possible if it weren\’t for the hemoglobin in erythrocyte’s. Hemoglobin is the protein that transports oxygen throughout the bloodstream. The rate at which hemoglobin delivers oxygen to the muscles increases when erythrocytotis exists. "Hemoglobin accounts for over 95 percent of the erythrocyte\’s proteins." (2) A hemoglobin molecule is composed of four proteins, each of which contains a single heme group.

Heme Group: (5)

A heme group is composed of an iron in the center covalently bonded with four nitrogen atoms. (6)

"Role of Hemoglobin in oxygen transport" (6)

This diagram explains the process of hemoglobin transportation. Hemoglobin is transported through the veins to the heart and then into the lungs, where oxygen binds to the hemoglobin, to produce oxyhemoglobin (oxygenated hemoglobin). The oxyhemoglobin then travels out through the arteries to the oxygen depleted tissues (muscles) of the athletes. Oxyhemoglobin then releases the oxygen, forming deoxyhemoglobin which is then transported back into the veins to start the process all over again.

Reaction between Hemoglobin (Hb) and oxygen: (5)

Hb + O2	↔	HbO2
HbO2 + O2	↔	Hb(O2)2
Hb(O2)2 + O2	↔	Hb(O2)3
Hb(O2)3 + O2	↔	Hb(O2)4

"There are approximately 280 million molecules of Hemoglobin in each red blood cell." (2) In each hemoglobin there are four heme units that are able to carry more than a billion molecules of oxygen. The more blood circulating through the circulatory system and reaching the muscles the more oxygen there is to enhance the athletes performance.

There are consequences for those athletes that use autologous or homologous blood doping. One important factor for athletes to think about is the tremendous strain that can be placed upon their heart. Increasing the number of erythrocytes thickens the blood circulating through the body, forcing the heart to pump harder. Athletes take the risk of developing a heart attack or even a stroke just to increase their endurance. A natural alternative is training at high altitudes which induces erythrocytosis without having to be infused with homologous or autologous blood. People who live at altitudes of 10,000 to 12,000 feet above sea level experience erythrocytosis, although to a lesser degree than with Homologous or Autologous blood doping.

Many athletes choose to train at higher elevations because it is the only legal way to induce erythrocytosis. Blood doping in any form is considered illegal in all endurance sports according to Olympic regulations. Homologous blood doping can be detected by a homologous blood transfusion test. This involves a flow cytometer, a machine that isolates, identifies, and counts all red blood cells in a blood sample. The sample is exposed to primary antibodies, generally about five or six, which are set up to bind to a specific blood cell type. By using a variety of antibodies, it is possible to test for each of the specific blood type. There are four blood types: O, A, B, and AB, and each either + or -. If only major types of blood (A, AB, B, O) existed, blood doping would be almost undetectable. However, each person has a specific subtype of blood (eg, A_e A_f and A_g). These subtypes do not prohibit a person from receiving other subtypes of their blood type but the various subtypes are detectable through tests. Since each person only has one specific blood subtype occurring in them naturally, the presence of more than one is evidence of blood doping. The test to determine homologous blood doping is called a cytometer. The test utilizes antigens which bind to specific blood subtypes and analyzing the results given as a simple spike chart read out. The antigens are used in testing attach themselves to a specific version of the red blood cell. These antigens are added to the sample before they are put into the flow cytometer. The antigens corresponding to the red blood cell versions are then marked with a florescent tag. The sample is then put in the flow cytometer; the florescent treatment allows the cytometer to identify the various antigens. The results are in the form of a chart. If there is only one spike on the chart then there is only one blood cell type of pure/clean sample. If the chart has more than one peak, then the flow cytometer has picked up on the florescent tags of multiple antigens. This means there are at least two different blood populations in the sample.

Autologous blood doping can be detected in only one way. This is to do a simple red blood cell count. If the hemocrit level is over 50%, the athlete is automatically labeled as having done autologous blood doping. The average person has a red blood cell percentage of 45%. While there are new ways to detect blood doping in development, none have been proven to be reliable making the red blood cell count the only way to detect autologous blood doping.

Autologous and homologous blood doping are common ways in which athletes illegally enhance their performance. Common dangers involved in the process are heart attacks from over worked hearts and strokes. The health dangers an athlete risks contracting, as well as the unfair advantage given by practicing blood doping have caused concerns. Tests have been developed and continue to be developed to detect and deter Athletes from using autologous homologous blood doping. A clear understanding of the biology and chemistry of this practice and the physiological processes involved is needed to develop more ways to detect autologous and homologous blood doping. This understanding will help to develop safer methods for athletes to train.

"Researched and written by: Robyn Brostrom, Jackie Anderson, Elizabeth Laudolff and Sarah Jutila"

Footnotes

1. ESPN.com, American\’s gold medal threatened by test. http://sports.espn.go.com (accessed 09/20/2005)
2. Martini F.H, Timmons M.J, Tallitsch R.B. Human Anatomy 4th ed, Prentice-Hall, 2003; pp. 538-545.
3. Nelson et. Al "Proof of homologous blood transfusion through quantification of blood group antigens." Halmatologia, vol.88 (11) November 2003.
4. Silberberg, Martin S. Chemistry The molecular Nature of Matter and Change 3rd ed, McGraw-Hill, 2003;pp.1032-1033.
5. Wikipedia, The free encyclopedia, http://en.wikipedia.org/wiki/Hemoglobin. (accessed 09/27/2005)
6. Garrett, Grisham. Biochemistry, Saunders, 1995; http://www.people.virgina.edu/ (accessed 09/27/2005)