Featured Research

from universities, journals, and other organizations

The Strange Tale Of Muscle Lactate: When The Villain Becomes Your Friend

Date:
June 1, 2007
Source:
Blackwell Publishing Ltd.
Summary:
Scientists add to the growing literature leading to a more complete understanding of the physiological role of lactic acid production in muscle.

In an article published in The Journal of Physiology, Frank de Paoli and colleagues, working at the University of Aarhus in Denmark, add to the growing literature leading to a more complete understanding of the physiological role of lactic acid production in muscle.

Related Articles


In the late 19th century, fermentation chemists realized that juice left to ferment without adequate oxygen resulted in acid products. Then, in the early 20th century, when physiologists stimulated isolated frog muscles to contract until exhaustion, they found that the tissues had accumulated high amounts of lactic acid. Since then, the idea that lactic acid accumulation causes muscle fatigue has persisted.

But did early scientists fail to address the various issues adequately and interpret the results appropriately? Did they fail to ask the essential question? "Why does nature make lactic acid?", and did they in effect put one and one together and make them a minus?

De Paoli and colleagues looked at the effects of lactic acid and adrenaline on the processes that signal contractions in skeletal muscles. Using rat muscles, the study examined the combined effect of potassium ions, lactic acid and adrenaline on the electrical signalling system that serves to forward the activating signals from the brain to the muscle fibres where contraction takes place.

They showed that in combination, lactic acid and adrenalin serve to help working muscles ward off the effects of potassium ions which leak from the inside to the outside of working muscle cells and negatively effect the signaling process by which muscles contract. In this, the latest of a series of reports from the Aarhus group, in combination with reports from other scientists in Scandinavia, the UK, US and Canada, long-standing ideas about the role of lactic acid in muscle are being overturned.

So, why do muscles contract? Usually, muscles contract because the central and peripheral nervous system signals them to do so.

Why do the muscles make lactic acid? Lactic acid is the result of the glycolytic energy production system. It is an energy source to be used in muscle cells of origin, or adjacent fibres (cells), or fibres in the heart and cells in the brain. Lactic acid is also the material that the liver prefers to make glucose (sugar) for the blood when exercise is prolonged. Lactic acid production in muscle is stimulated in part by circulating adrenalin. Now, from de Paoli and colleagues we learn that adrenalin and lactic acid also help protect against the electrolyte imbalance across muscle membranes brought on by the loss of potassium.

Why does potassium have such a negative effect? In the study, when potassium ions outside the muscle fibres were increased to levels seen during intense exercise, the ability of the signalling system to forward electrical signals was profoundly reduced and the muscle became paralysed. If, however, lactic acid and adrenaline were added in combination, the function of the signalling system was largely recovered and the contractile response of the muscles restored. It was further shown that the positive effect of lactic acid was specifically related to an acidification of the interior of the muscle cells, which is one of the hallmarks of intense exercise.

The muscle lactic acid story, however, is still incomplete. It may even be found that lactate production is adaptive because its presence signals the activation of genes responsible for controlling muscle function. So, it seems that there is wisdom in the way that the body functions, a retrospective realisation that seems obvious, and which for lactic acid is supported by a century of strides even after a few false steps.


Story Source:

The above story is based on materials provided by Blackwell Publishing Ltd.. Note: Materials may be edited for content and length.


Cite This Page:

Blackwell Publishing Ltd.. "The Strange Tale Of Muscle Lactate: When The Villain Becomes Your Friend." ScienceDaily. ScienceDaily, 1 June 2007. <www.sciencedaily.com/releases/2007/05/070531191121.htm>.
Blackwell Publishing Ltd.. (2007, June 1). The Strange Tale Of Muscle Lactate: When The Villain Becomes Your Friend. ScienceDaily. Retrieved November 26, 2014 from www.sciencedaily.com/releases/2007/05/070531191121.htm
Blackwell Publishing Ltd.. "The Strange Tale Of Muscle Lactate: When The Villain Becomes Your Friend." ScienceDaily. www.sciencedaily.com/releases/2007/05/070531191121.htm (accessed November 26, 2014).

Share This


More From ScienceDaily



More Health & Medicine News

Wednesday, November 26, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

From Popcorn To Vending Snacks: FDA Ups Calorie Count Rules

From Popcorn To Vending Snacks: FDA Ups Calorie Count Rules

Newsy (Nov. 25, 2014) — The US FDA is announcing new calorie rules on Tuesday that will require everywhere from theaters to vending machines to include calorie counts. Video provided by Newsy
Powered by NewsLook.com
Daily Serving Of Yogurt Could Reduce Risk Of Type 2 Diabetes

Daily Serving Of Yogurt Could Reduce Risk Of Type 2 Diabetes

Newsy (Nov. 25, 2014) — Need another reason to eat yogurt every day? Researchers now say it could reduce a person's risk of developing type 2 diabetes. Video provided by Newsy
Powered by NewsLook.com
Madagascar Working to Contain Plague Outbreak

Madagascar Working to Contain Plague Outbreak

AFP (Nov. 24, 2014) — Madagascar said Monday it is trying to contain an outbreak of plague -- similar to the Black Death that swept Medieval Europe -- that has killed 40 people and is spreading to the capital Antananarivo. Duration: 00:42 Video provided by AFP
Powered by NewsLook.com
Are Female Bosses More Likely To Be Depressed?

Are Female Bosses More Likely To Be Depressed?

Newsy (Nov. 24, 2014) — A new study links greater authority with increased depressive symptoms among women in the workplace. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins