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Mitochondrial Toxicity

By Ana Rodriguez

Spring 2001

What are mitochondria? What do they do? And how does it affect me?

Take into account that our bodies are made up of billions of tiny cells with different functions that help us live. The mitochondria are tiny organisms inside the cell, and their job is to produce energy for the cell. Many sources call them the "power plants" or "powerhouses" of the cell. Mitochondria utilize and break down the oxygen, fat and sugar of the cell to produce adenosine triphosphate or ATP. This process gives energy to the cell when needed. The cells then generate this energy throughout our body. This energy helps us run a mile, or be able to walk 3 blocks without getting fatigued, or simply to get up in the morning. It is uncertain how many mitochondria live in the cell, and it depends on how much energy the cell needs. It can range from a couple of mitochondria to thousands. The cells with high mitochondrial levels are found in the muscles, liver and nerves.

Dysfunctional Mutations

One of the particulars of the mitochondria is that, although they are a component of the cell, they reproduce independently of the cell. The genetic composition of the mitochondria is unique as it uses a different DNA to replicate itself than the nuclear DNA that the cell uses for reproduction. However, the mitochondria are very delicate in their reproduction because they can reproduce defective mitochondria, and are not able to correct themselves like the nuclear cells do. Gradually, the mitochondria, at some point, will reproduce more dysfunctional mutations and less functional ones. With fewer functional mitochondria in the cell, the less energy the cell will be receiving. In order for the cell to receive the needed energy, it utilizes a process called anaerobic (without oxygen) metabolism, which is inefficient and produces more lactate. Some experts believe that the process of getting old is related to the gradual break-down of the mitochondria. When the mitochondria stop performing, many illnesses can arise. This is what is called mitochondrial toxicity. Some diseases related to mitochondrial dysfunction are lactic acidosis, neuropathy, muscle wasting, anemia, and pancreatitis, among many.

How does mitochondrial toxicity relate to HIV infection?

Lactic Acidosis

The mitochondria use an enzyme to reproduce similar to the reverse transcriptase enzyme that many anti-retroviral medications use. Experts are theorizing that long-term use of some anti-retroviral medications (AZT, 3TC, ddI, ddC, d4T, and abacavir) may affect the ability of the mitochondria to reproduce properly, thus causing some side effects related to mitchondrial toxicity. For example, lactic acidosis is a rare condition, which affects the muscles, and can create a high build-up of lactic acid in the blood. This condition, if not checked, can be fatal. The symptoms associated with lactic acidosis are nausea, vomiting, fatigue, and recent weight loss. It is very important to see a doctor if a person is experiencing these symptoms while taking any of the anti-retroviral medications. It is also believed that lipodistrophy syndrome is associated with mitochondrial toxicity. The National Association of People with AIDS' A Guide to Understanding Lipodystrophy Syndrome (NAPWA 2000) states that "Some researchers believe NRTIs may affect the mitochondria in fat cells, leading to changes in the distribution of body fat." The medical research about this subject is very limited. Many experts also associate mitochondrial toxicity to the effects of HIV infection itself. However, it is still uncertain if medications or HIV is the cause of mitochondrial failure. Yet, many people with HIV have been experiencing many of the diseases stated above. It is important that you become informed and talk to your doctor, and experts on HIV infection about the long-term effects of anti-retroviral medications, and how to manage the possible side effects associated with them.


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