Discussion #3 Performance-enhancing drugs
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Athletes spend hundreds of hours training, trying to build their endurance. For Johann Muehlegg, a cross-country skier at the 2002 Salt Lake City Winter Olympics, it appeared that his training had paid off when he captured three gold medals. On the last day of the Games, however, Olympics officials expelled Muehlegg and stripped him of his gold medal in the 50-kilometer classical race. The reason? Muehlegg had tested positive for a performance-enhancing chemical that increased the oxygen-carrying capacity of his blood. Officials claimed Muehlegg’s endurance in the grueling race was the result of blood doping, not training.
The first sign that Muehlegg might be cheating by this method was the result of a simple blood test for hemoglobin and hematocrit, taken several hours before his 50-km race. Muehlegg’s blood hemoglobin level registered above 17.5 g/dL.
A repeat test was within acceptable limits, however, and Muehlegg was allowed to race. Muehlegg claimed that his elevated hemoglobin was a result of his special diet and diarrhea he had suffered the night before.
After the 1984, the International Olympic Committee and other organizations banned blood doping. Then recombinant human EPO (rhEPO) became available in the late 1980s, and athletes started injecting the drug to increase their body’s red blood cell production. Subsequently the biotechnology firm Amgen created a longer-acting derivative of EPO named darbepoetin. Athletes using rhEPO and darbepoetin hoped to escape detection by using these natural hormones, but sports organizations worked with scientists to develop methods for detection.
1. Explain how diarrhea could cause a temporarily elevated hematocrit.
2. How might Muehlegg quickly reduce his hematocrit without removing red blood cells?
3. Endogenous EPO, rhEPO, and darbepoetin all induce red blood cell synthesis, but they can be distinguished from one another when a urine sample is tested by electrophoresis. Explain how three hormones made from the same gene can all be active yet different enough from one another to be detectable in the laboratory.
4. One hallmark of illegal EPO use is elevated reticulocytes in the blood. Why would this suggest greater-than-normal EPO activity?
Your response must be between 400 to 500 words.