Taurine and Osmoregulation
By:
Derek Charlebois B.S. CPT
When cell membranes are excited, such
as during skeletal muscle contraction, ions cross the membrane through
controlled channels. This process can cause ionic imbalances across
the membrane, creating osmotic stress. Water does not use channels
and can readily diffuse across cell membranes. This is called osmosis.
When ionic imbalances occur, water diffuses across the membrane
until the osmolarity (total solute concentration of a solution)
on both sides is equal.
Cell Membrane
Another option is for other compounds to be transported in/out
of the cell. In an attempt to maintain the cell’s concentration
gradient, it may synthesize a metabolically inert or nonessential
compound for use or use other important compounds. Synthesizing
this compound requires energy and essential nutrients, specifically
amino acids, are often to meet these demands.
Osmoregulation means “giving the cell the capacity for osmotic adaptation:
in other words, allowing the cell to respond to the stress of a
changing environment.” [6] Exercise causes stress upon the body,
changing its environment to from not a homeostasis. If one could
optimize the process of osmoregulation, athletic performance would
be enhanced. This can be done through precise supplementation.
L Taurine
What is it?
Taurine is a nonessential amino acid, but has been deemed a semi-essential
amino acid by many researchers. It is the most abundant amino acid
in skeletal muscle, the heart, brain, leukocytes, and the retina
of the eye. Unlike other amino acids, taurine is not used in protein
synthesis.
Taurine
What does it do?
Taurine participates in calcium modulation, membrane stabilization,
modulation of neuronal excitability, central nervous system development,
reproduction, and immunity [1]. Other metabolic actions are bile
acid conjugation, osmoregulation, and detoxification [5]. Taurine
has been used to treat epilepsy, hypercholesterolemia, Alzheimer’s
disease, cystic fibrosis, and cardiovascular diseases [5]. So
what exactly can it do for the normal, healthy athlete?
Exercise causes damage to skeletal muscle and connective tissue
through oxidative stress (exercise increases free radical production).
This is why many people take antioxidants, such as vitamin C and
E, after they exercise. Taurine has anti-inflammatory properties
that can decrease tissue damage due to inflammation [1], which should
help one recover from exercise by decreasing exercise-induced muscle
damage [3].
Taurine modulates cellular calcium flux (enter and exit of the cell)
in muscle, specifically in the heart. Calcium (Ca2+) plays an important
role in muscle contraction. When a muscle is signalled to contract,
Ca2+ is released from the sarcoplasmic reticulum (storage site for
calcium). This Ca2+ then binds to specific binding sites which stimulate
contraction. Ca2+ does not require energy to enter into the cell,
but it does require energy to exit it. This movement is regulated
by a Ca2+ pump. Taurine has been shown to increase the pumping rate
of this ATPase pump. Taurine also increases the sarcoplasmic reticulum’s
Ca2+ storage capacity. Taurine also stabilizes muscle membrane integrity.
For example, in heart muscle, taurine decreases passive “leakage”
of Ca2+ through the membrane by maintaining its impermeability [6].
Taurine can increase Ca2+ availability when it is low and protect
against high levels of Ca2+, which means optimal performance for
muscle tissue, specifically in the heart.
Calcium is needed for skeletal muscle contraction to occur
Taurine has insulin-like actions. It has been shown to increase
glucose uptake, glycogenesis, glycolysis, and glucose oxidation.
Taurine also potentiates insulin release and has be shown to decrease
blood glucose levels by increasing muscle clearance (glucose uptake)
[6].
Taurine can be used as an osmoregulator (termed an osmolyte), which
spares other important compounds, such as amino acids, from being
transported out of the cell [6]. An example of taurine in action
is with glucose metabolism. Metabolism and entry of glucose into
a cell is coupled with the entry of water. Researchers believe that
taurine removes the water from the cell, thereby maintaining the
cell’ osmolarity [6]. Taurine’s affect on water and ion movement
has the potential to restore the osmotic equilibrium across the
cell membrane, which creates an optimal environment for performance
and growth.
Exercise depletes taurine levels in the working skeletal muscles
[2], specifically from fast-twitch fibers [4]. Supplementing with
taurine will ensure that you have optimal levels for heightened
performance. Simply adding a couple grams of taurine to your post-workout
shake will enhance your results.
Derek “The Beast” Charlebois is
an ACE certified personal trainer, competitive bodybuilder, and
holds a Bachelor’s degree in Exercise Science from The University
of Michigan. Derek is the Promotions Coordinator/R&D at Scivation/Primaforce
and is involved in coordinating promotions, research and development,
advertising, and marketing. Derek is an accomplished author with
articles on such websites as Bodybuilding.com, Bulknutrition.com,
the online magazines StrengthAndScience.com and MusclesAndCuts.com,
and is a contributing author to the book Game Over: The
Final Showtime Cut Diet You’ll Ever Need! Derek is available
for online personal training. His website is www.beastpersonaltraining.com.
Derek can be reached at derek@scivation.com
References:
1. Georgia B. Schuller-Levis, Eunkyue Park. Taurine: new implications
for an old amino acid FEMS Microbiology Letters 226 (2003) 195-202.
2. Matsuzaki Y, Miyazaki T, Miyakawa S, Bouscarel B, Ikegami T,
Tanaka N. Decreased taurine concentration in skeletal muscles after
exercise for various durations. Med Sci Sports Exerc 2002
May;34(5):793-7
3. Dawson Jr R, Biasetti M, Messina S, Dominy J. The cytoprotective
role of taurine in exercise-induced muscle injury. Amino Acids 2002;22(4):309-24.
4. Matsuzaki Y, Miyazaki T, Miyakawa S, Bouscarel B, Ikegami T,
Tanaka N.Decreased taurine concentration in skeletal muscles after
exercise for various durations. Med Sci Sports Exerc. 2002 May;34(5):793-7.
5. Birdsall TC. Therapeutic applications of taurine. Altern Med
Rev. 1998 Apr;3(2):128-36.
6. R. J. HUXTABLE Physiological Actions
of Taurine PHYSIOLOGICAL REVIEWS Vol. 72, No. 1, January 1992.
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