Talk:Lactic acid

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[edit] Clarify Lactic Acid and Lactate

I came to this article to read up on the effects of lactate on muscle performance with a substantial background knowledge in cellular biology and chemistry. But, my concern is that the article doesn't clarify the difference between the two compounds sufficiently. It can appear confusing that half the article is discussing lactic acid in milk and other dairy products and then the other half is about lactic acid's derivative lactate and what its effects in muscles are.

I propose either splitting the articles into two or clarifying the difference better between the two compounds. --Novaprospekt 22:58, 2 May 2007 (UTC)

I agree that it's currently unclear. I think for the moment, it would be best to just clarify it and split the article later when it gets bigger. I'll work on something over the next couple of days. Rerun 06:44, 14 May 2007 (UTC)

After thinking about this for a while and trying to come up with a workable solution, I've changed my mind and now think that it would be best to split the article, similar to acetate and acetic acid. I think there is enough information present to warrant a separate page for each. However I don't want to rush ahead and do this. I'll wait two weeks and if no one has any objections I'll split the pages. I'm open to discussion so if anyone wants the page to stay as it is, please leave a message if you do Rerun 05:15, 22 May 2007 (UTC)

Certainly one could focus on the biological aspects and the other on the chemical. It might work. David D. (Talk) 05:18, 22 May 2007 (UTC)

As it appears discussion of lactate is staying in this article, I have changed lactate from a redirect to a disambiguation page and also fixed all mainspace links to lactate. --Una Smith (talk) 04:24, 20 December 2007 (UTC)

[edit] Image

Sorry for inserting the image in such a messy manner. It looks like Wikipedia won't use the HTML I'm used to. Could someone else please straighten out the image and make it "fit" th entry?? Sorry I'm so much of an amateur at these things right now.

Why isn't there a structural formula on the page? Space-filling models are peachy, sure, but it would be nice to have a line drawing...

[edit] Lactic build up myth

(copied from my post on DOMS) Lactic acid(actually lactate) is associated with sore muscles, but it has been shown not to be the cause of the soreness. It has been found that people with greater endurance have higher levels of lactate, and with some further experiments showed that lactate is actually beneficial for reducing soreness and protecting the muscles.

http://www.abc.net.au/catalyst/stories/s1314443.htm http://www.time-to-run.com/theabc/lactic.htm njh 23:31, 6 October 2005 (UTC)

OK- it now turns out the lactic acid is FUEL for muscles.... so this section might need an update? http://www.nytimes.com/2006/05/16/health/nutrition/16run.html?ex=1148097600&en=1d44fa0b49133c03&ei=5087%0A --spiralhighway 19:03, 18 May 2006 (UTC)

[edit] Wrong picture

The bottom space-filling model seems to be glycine and not lactic acid.

[edit] Melting Point

Most MSDS's I have found show the melting point of lactic acid to be 18C or around 64F

In this case, the single enantiomers crystalize differently than the racemate, so they have different melting points. I have added this info into the article. --Ed (Edgar181) 19:25, 20 March 2006 (UTC)

[edit] Additions

I have made a fair few changes to this page as a lot of the information was outdated. I expect people will be a little concerned over the information I posted that says that we don't produce lactic acid. The best way to investigate this is to find a a picture of glycolysis and start counting the hydrogens and you'll find that it's not possible to make lactic acid under normal conditions. Also, have a read of the last external link posted for more information about this.

[edit] Strong ion difference

I reverted the part in Exercise and lactate about lactate and burning etc, to indicate that lactate does not "directly" cause acidosis. I don't know much about the SID stuff, but removing the phrase above makes the rest of the paragraph less cohesive.

Basically, it means that a strong ion or anion, such as lactate, can have a direct effect on the pH, just by changing the ratio of strong ions to strong anions. For example, a large quantity of sodium-lactate, which is basically a strong ion (Na) and a strong anion (lactate), will cause acidosis, because it has a SID of 0, while the human blood has a SID of about 30. Note that this means that even a base like lactate (not lactic acid!), and even though sodium lactate is not capable of releasing a proton, can cause acidosis!
That whole paragraph is wrong, and should be rewritten Terrapin2001 18:02, 2 January 2007 (UTC)

[edit] Wrong

"Without lactate, increased concentrations of pyruvate would inhibit glycolysis and greatly reduce ATP production."

Lactate is a product of pyruvate oxidation. But sentence seems to say that lack of lactate causes increase in concentration of pyruvate. What really happens is that lack of lactate and increased concentration of pyruvate can be result of, say, impaired function of lactate dehydrogenase.

[edit] Wrong?

If you take the sentence out of the context of the paragraph, then yes it will sound wrong. The paragraph is talking about increases in lactate production, which occurs when pyruvate dehydrogenase doesn't process the pyruvate quick enough (impaired LDH function would be a separate issue). Thus the need for pyr-->la since without it pyruvate would build up and and inhbit glycolysis under conditions where PDH isn't working quick enough. I have edited it nonetheless to make this clearer.

[edit] Cosmetic Usage

Shouldnt there be a section discussing the role of lactic acid in skin care? I'll add that in the mean time and discuss if you dont think that belongs there. --Chicbicyclist 14:34, 28 January 2006 (UTC)

[edit] ATP factiod highly unlikely; Lactic Acid produced, disassociates

One paragraph states that: "The acidosis that is associated with increases in lactate concentration during heavy exercise arises from a completely separate reaction."

The body produces Lactic acid during anaerobic exercise, which then disassociates into Lactate and free H+ ions, which acidify the blood. Only once the lactate and extra H+ ions pass through the heart and then through the liver are they converted into glucose; this takes some time, yet the article suggests this process happens instantaneously. Also, ATP hydrolysis occurs EVERYWERE in the body ALL THE TIME so a little increase in hydrolysis in the muscles cant be expected to highly acidify the body. Can someone help fix these errors? Or at least explain in a little more detail with a little more clarity.

The article's very own reference [1] correctly identifies Lactic acid as the acidifying culprit. It should also be noted that the extra H+ ions released by Lactic acid cause O2 and haemoglobin to disassociate more readily, aiding in oxygen delivery to the active muscles. 138.16.19.127 00:32, 11 April 2006 (UTC)

[edit] Lactic acid isn't produced

1) I'll get rid of that link you've quoted as it is misleading and partially incorrect.

2) The body *doesn't* produce lactic acid during exercise, if you look at the last external link you'll see a thorough discussion on why. Briefly, as it is mentioned in the article, the aren't enough hydrogens present at the end of glycolysis to produce lactic acid at physiological pH. What you produce is lactate since the pKa's of the molecules in glycolysis favour a dissociated state (right from the start) so it is not possible to produce lactic acid as there isn't enough hydrogens i.e. the end of glycolysis produces pyruvate, not pyruvic acid. The old "lactic acid" theory is an unfortunate bit of dogma that just wont die.

3) Lactate doesn't always go to the liver to undergo gluconeogenesis. Some of it diffuses into adjacent muscle fibres to be converted back to pyruvate and then proceeds through the Krebs cycle.

4) The ATP hydrolysis during exercise isn't a *little* bit, it is quite substantial. The reason why we don't become acidotic all the time is because we have buffering systems (namely HCO3) to prevent this. But during heavy exercise, ATP hydrolysis happens at a high rate which essentially depletes the HCO3 and then results in an acidotic state.

5) The section is not specifically referring to acidification of the blood, but just in general as the muscle tissue will also become more acidic.

6) I will review the section and attempt to make this clearer

[edit] Lactic acid is produced

Well, it depends on how you look at it. If you look at the reaction from glucose to lactate, the net result is 2 lactate, 2H+ and 2ATP which gives a lower pH. I admit that the acid is dissociated from the very beginning but it's not incorrect to say that the body produces lactic acid, just a bit sloppy. The reason for the lactate buildup is the lack of oxygen needed for the citric acid cycle and the oxidative decarboxylation where the H+ ions are reduced to water. --Eribro 22:27, 3 May 2006 (UTC)

The reaction from glucose to lactate actually consumes hydrogen. I think you're mixing up the glycolysis and lactate reactions.

Glucose + 2ADP + 2Pi + 2NAD⁺ -->2 pyruvate + 2 ATP + 2 NADH + 2H⁺ + 2H₂O

2Pyruvate + 2NADH + 2H⁺ -->2lactate + 2NAD⁺

Net is therefore

Glucose + 2ADP + 2Pi -->2 ATP + 2H₂O + 2 lactate

While lack of oxygen can cause an increase in lactate concentrations, it's not the defining factor per se, it has more to do with the pyruvate dehydrogenase reaction. About 50% of glucose goes to lactate at rest (when we certainly aren't oxygen deprived), but it gets converted back to pyruvate so we don't get any increase in concentration. A minor detail, but I thought you might be interested. Rerun 04:08, 2 June 2006 (UTC)

[edit] Vandalism

This page has been vandalized twice by the IP address 71.141.251.75 with senseless bashing of "emo" and "hardcore" music (probably just umbrella terms for music he/she doesn't like). I recommend this IP be blocked immediately.--Terminus-Est 03:48, 22 September 2006 (UTC)

Blockings are done at WP:AIV. Richard001 07:50, 21 August 2007 (UTC)

[edit] Clearance and Use as Energy

I was thinking that there should be some statement on the clearance of lactate into the blood, particularly in respect to its measurement in short-duration, high-intensity exercise. Also, the importance of lactate as an energy source, esp. for the heart. Its metabolism should be discussed, as the Cori Cycle link is woefully inadequate and seems to be dated. —The preceding unsigned comment was added by 207.81.125.94 (talk • contribs) 12:28, 3 December 2006.

[edit] Industrial uses

The article has become highly anthropocentric. A good starting point for researching other applications of LA is at http://www.lactic.com/ --Zymatik 20:02, 19 December 2006 (UTC)

[edit] pKa

What about its Ka value ? I need it ASAP!

[edit] L and D forms

I was wondering if anyone could tell me, why some bacteria produce both the L and the D form of Lactate?

This is because the D combine with the H particle which in turn is m producing l.

That can't be right, the difference between the L and D form is that they are chiral. So it wouldn't make sence if the L form is produced from adding an ekstra H particle to the D form. The question is, If I werent to clear on it before, Why do some bakteria, when they ferment Lactose to lactate, produce both L and the D form of it? —Preceding unsigned comment added by 195.24.10.179 (talk) 07:37, 15 October 2007 (UTC)

[edit] How long ?

Why can't Lactic acid be the main source of energy for the body. I mean it does most of the work...get rid of ATP-PC and aerobic. Woot for lactic acid ! —Preceding unsigned comment added by 124.187.70.5 (talk) 06:10, 15 October 2007 (UTC)

[edit] Missing Hydrogen?

Isnt the picture missing a Hydrogen atom? The Carbon only has 3 bonds. —Preceding unsigned comment added by 89.243.227.109 (talk) 01:10, 16 December 2007 (UTC)

Carbon-hydrogen bonds are not typically shown on molecular structure diagrams. By convention, it is assumed that any missing carbon bonds are hydrogen. Sorry if that sounds a tad confusing...for example, the structural drawing of ethane (C₂H₆) would be a straight line representing the carbon-carbon bond. The remaining 6 carbon-hydrogen bonds are not shown.

[edit] Zinc lactate

I noticed zinc lactate listed as a mouthwash ingredient. That page doesn't exist and lactate disambiguates to this page. Would anyone care to start the page zinc lactate? —BenFrantzDale 03:45, 8 March 2008 (UTC)