What happens after a person receives a traumatic brain injury? Tissue damage and swelling often results in neural tissue being unable to receiving adequate levels of glucose which are required to "feed" the brain. This deprivation of energy can cause further injury to tissue, so often times an artifical supply of glucose is given to the brain to stave off those bad effects within the first few hours of injury.
Now this traditional food source may take a back-seat to lactate: the chemical that makes your tired muscles "feel the burn" and gives sour milk its, well, sourness. Researchers at UCLA have recently shown that the brain takes up lactate following an injury.
...the researchers found that in the first 12 to 48 hours following traumatic injury, the brain takes up and apparently consumes more lactate than at any other time. They discovered this by measuring the levels of lactate in blood entering and leaving the brain. To determine if lactate was being used by the brain, the researchers, in collaboration with George Brooks, a professor in the department of integrative biology at the University of California, Berkeley, labeled lactate with C13, a non-radioactive and stable isotope, then added it to the patient's standard intravenous solution. The isotope served as a marker they could follow to see if the lactate molecule had produced carbon dioxide, the natural byproduct of lactate after use by the brain as fuel."Our preliminary tracer-based studies demonstrated the novel and unexpected finding of both lactate uptake and its utilization as fuel in traumatic brain injury," Glenn said. "These results have led us to challenge the current conventional wisdom concerning the type of fuel the brain uses after injury to generate the energy for recovery."
The theory goes that after a brain injury, neural tissue cannot utilize glucose normally, and glucose is directed to other uses. Instead, lactate is the preferred energy source during times of injury, which makes it a better candidate to administer to patients who need an artifical fuel source.
Below: Lactate uptake in the injured (top) versus (normal) brain.
Source abstract.
Comments
I was going to shoot you a link to that article but I see you are already way ahead of me. :-)
Posted by: Boosterz | April 12, 2007 4:34 PM
Yeah, interesting stuff. Makes me feel sorry for all the poor patients who received glucose--pretty futile, turns out.
Posted by: Shelley | April 12, 2007 4:38 PM
This makes me wonder if other stressed/injured tissues besides brain might also be utilizing more lactate.
Posted by: chezjake | April 12, 2007 5:00 PM
Could be, however brain tissue makes sense in that it was the first system studied due to the *amount* of energy it consumes both normally and during repair after injury. (Not to mention the medical need for good response to a brain injury). The brain is also a bit more isolated in terms of blood supply than many other potentially-damaged tissue. Brain injuries often result in the blood flow to a part of the brain being disrupted or reduced, which is not as often the case in more centrally-located organs which receive many sources of blood supply. However, I think that severed limbs/digits or other hypoxic tissues (heart attack?) might be a great place to start.
Posted by: Shelley | April 12, 2007 5:06 PM
Ah, me with my little B.S. Was this limited to any specific type of TBI, or is "pericontusional" a catch-all term for any injury that creates swelling?
Posted by: Brian | April 12, 2007 7:41 PM
lactate: the chemical that makes your tired muscles "feel the burn"
Lactate by itself will not cause muscles to burn, in fact, the lactate ion by itself will act to buffer the acidosis that is much more likely to be the major cause of the burn. If ATP demand exceeds the ability of the mitochondria to produce it, part of the pyruvate from glycolyssi gets shunted to lactate, of if you are accounting for all the protons, lactic acid. Another major source of protons in producing acidosis is from hydrolysis of ATP [oxygen and probably one proton added from water and another free proton]. The burn goes away much faster than muscle or blood lactate. And lactate is readily used by muscle fibers with higher oxidative potential - which includes the heart.
SB: Thanks for the info!
Posted by: natural cynic | April 13, 2007 12:07 AM
Well, that's going to be good news for a bodybuilder who's just dropped the weight on his head. Plenty of lactic acid around for recovery.
Posted by: Koray | April 13, 2007 3:28 AM
Interesting stuff. Unfortunately i keep finding research on what might have helped my wife at the time of her injury rather than in her recovery. Nobody seems to do research on helping those who already have anoxic brain injuries. http://www.getwellkathleen.us
Posted by: Mike Davey | April 13, 2007 3:19 PM