heart attack

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cathy00012345
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heart attack

Post by cathy00012345 » Thu Mar 23, 2006 2:46 am

After a heart attack, people often have small amounts of lactate in the blood, which comes from the injured heart. Can anyone suggest a reason for this? I really need help with this one. plz :lol:

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LilKim
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Post by LilKim » Thu Mar 23, 2006 3:04 am

I'm not sure exactly .... but I think you should look up info on the Biogenesis of Lactic Acid ... by muscle tissue.

... this is just a guess???

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cardiorrhexis
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Re: heart attack

Post by cardiorrhexis » Thu Mar 23, 2006 4:48 am

cathy00012345 wrote:After a heart attack, people often have small amounts of lactate in the blood, which comes from the injured heart. Can anyone suggest a reason for this? I really need help with this one. plz :lol:


Any time any muscle has any strain, the lactic acid levels (and cpk levels) go up...

Once the problem is corrected, the levels should eventually go back to normal ranges...


From my own personal experience...lactic acid monitoring doesn't mean diddly squat.
I can have a patient with a lactic acid level of 18 waltz right in, make it through surgery and go home the next day...where another patient can be at 7 and drop dead within 2 hours....

Basically, the entire physical status counts, not just one ( in this case... (IMO) ridiculous, uninformative, highly influenced by multiple factors) test result that can change at any given moment.


:D
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MrMistery
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Post by MrMistery » Thu Mar 23, 2006 8:00 pm

Here's the mollecular answer:
In glycolisis, glucose is broken down into 2 pyruvate molecules that enter the Krebs cycle under the form of acetyl~CoA. The process produces 2 ATP molecules and 2 NADH molecules. The 2 NADH molecules will serve for the synthesis of extra ATP in ocidative phosphorilation(2.5-3 ATP/NADH molecule to be exact) IF, AND ONLY IF oxigen is present. At the end of the whole process you end up with CO2, H2O and 38 ATP molecules. No lactate is produced. This is how any muscle(including heart muscle) gets it's energy for muscle contraction.
But if there is no O2 present, pyruvate can not enter the mithocondrion and therefore the process stops. Also, with no oxygen, oxidative phosphorilation can not take place. This is what happens during a heart attack. For a short while, the cells have a solution: they keep producing ATP by glycolisis, even though it is only 2 ATP/ glucose molecule. But, in order for glycolisis to take place, there must be free NAD+ molecules to accept the electrons. So the cell needs to recycle the NADH back to NAD+. This is done by reducing pyruvate to lactate. Contrary to oxidative phosphorilation, this reaction does not produce ATP. But now, the NAD+ molecules can accept electrons, and glycolisis can take place.
Unfortunately, unlike normal skeletical muscle cells, heart muscles have a very small quantity of the enzyme that reduces pyruvate to lactate. Due to this and other factors, the heart cell can undergo lactic fermentation for a very short time before necrosys takes place.

Provided by Andrew, your friendly neighbourhood biology geek...
"As a biologist, I firmly believe that when you're dead, you're dead. Except for what you live behind in history. That's the only afterlife" - J. Craig Venter

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