Osmotic shock
Encyclopedia
Osmotic shock or osmotic stress is a sudden change in the solute
concentration around a cell
, causing a rapid change in the movement of water across its cell membrane
. Under conditions of high concentrations of either salt
s, substrates
or any solute in the supernatant, water is drawn out of the cells through osmosis
. This also inhibits the transport of substrates and cofactors into the cell thus “shocking” the cell. Alternatively, at low concentrations of solutes, water enters the cell in large amounts, causing it to swell and either burst or undergo apoptosis
.
All organisms have mechanisms to respond to osmotic shock, with sensors and signal transduction
networks providing information to the cell about the osmolarity
of its surroundings, these signals activate responses to deal with extreme conditions. Although single-celled organisms are more vulnerable to osmotic shock, since they are directly exposed to their environment, cells in large animals such as mammals still suffer these stresses under some conditions.
Calcium acts as one of the primary regulators of osmotic stress. Intracellular calcium levels rise during hypo-osmotic and hyper-osmotic stresses. During hyper-osmotic stress extracellular albumin
binds calcium.
by blood Albumin
Transient intracellular Ca2+ increase.
Calcium dependent efflux of the osmolyte Taurine. Extracellular calcium removal was found to prevent Taurine efflux by 50%, and removal of extracellular Ca2+ and simultaneous depletion of intracellular Ca2+ stores with thapsigargin
decreased it by 85%..
Solution
In chemistry, a solution is a homogeneous mixture composed of only one phase. In such a mixture, a solute is dissolved in another substance, known as a solvent. The solvent does the dissolving.- Types of solutions :...
concentration around a cell
Cell (biology)
The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....
, causing a rapid change in the movement of water across its cell membrane
Cell membrane
The cell membrane or plasma membrane is a biological membrane that separates the interior of all cells from the outside environment. The cell membrane is selectively permeable to ions and organic molecules and controls the movement of substances in and out of cells. It basically protects the cell...
. Under conditions of high concentrations of either salt
Salt
In chemistry, salts are ionic compounds that result from the neutralization reaction of an acid and a base. They are composed of cations and anions so that the product is electrically neutral...
s, substrates
Substrate (biology)
In biology a substrate is the surface a plant or animal lives upon and grows on. A substrate can include biotic or abiotic materials and animals. For example, encrusting algae that lives on a rock can be substrate for another animal that lives on top of the algae. See also substrate .-External...
or any solute in the supernatant, water is drawn out of the cells through osmosis
Osmosis
Osmosis is the movement of solvent molecules through a selectively permeable membrane into a region of higher solute concentration, aiming to equalize the solute concentrations on the two sides...
. This also inhibits the transport of substrates and cofactors into the cell thus “shocking” the cell. Alternatively, at low concentrations of solutes, water enters the cell in large amounts, causing it to swell and either burst or undergo apoptosis
Apoptosis
Apoptosis is the process of programmed cell death that may occur in multicellular organisms. Biochemical events lead to characteristic cell changes and death. These changes include blebbing, cell shrinkage, nuclear fragmentation, chromatin condensation, and chromosomal DNA fragmentation...
.
All organisms have mechanisms to respond to osmotic shock, with sensors and signal transduction
Signal transduction
Signal transduction occurs when an extracellular signaling molecule activates a cell surface receptor. In turn, this receptor alters intracellular molecules creating a response...
networks providing information to the cell about the osmolarity
Osmole (unit)
Osmolarity is the measure of solute concentration, defined as the number of osmoles of solute per litre of solution . The osmolarity of a solution is usually expressed as Osm/L , in the same way that the molarity of a solution is expressed as "M"...
of its surroundings, these signals activate responses to deal with extreme conditions. Although single-celled organisms are more vulnerable to osmotic shock, since they are directly exposed to their environment, cells in large animals such as mammals still suffer these stresses under some conditions.
Calcium acts as one of the primary regulators of osmotic stress. Intracellular calcium levels rise during hypo-osmotic and hyper-osmotic stresses. During hyper-osmotic stress extracellular albumin
Albumin
Albumin refers generally to any protein that is water soluble, which is moderately soluble in concentrated salt solutions, and experiences heat denaturation. They are commonly found in blood plasma, and are unique to other blood proteins in that they are not glycosylated...
binds calcium.
Recovery and tolerance mechanisms for hyper-osmotic stress
extracellular sequestering of CalciumCalcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...
by blood Albumin
Albumin
Albumin refers generally to any protein that is water soluble, which is moderately soluble in concentrated salt solutions, and experiences heat denaturation. They are commonly found in blood plasma, and are unique to other blood proteins in that they are not glycosylated...
Transient intracellular Ca2+ increase.
Recovery and tolerance mechanisms for hypo-osmotic stress
intracellular Ca2+ increase and Extracellular ATP ReleaseCalcium dependent efflux of the osmolyte Taurine. Extracellular calcium removal was found to prevent Taurine efflux by 50%, and removal of extracellular Ca2+ and simultaneous depletion of intracellular Ca2+ stores with thapsigargin
Thapsigargin
Thapsigargin is non-competitive inhibitor of a class of enzymes known by the acronym SERCA, which stands for sarco / endoplasmic reticulum Ca2+ ATPase. Structurally, thapsigargin is classified as a sesquiterpene lactone, and is extracted from a plant, Thapsia garganica. It is a tumor promoter in...
decreased it by 85%..
See also
- OsmolyteOsmolyteOsmolytes are compounds affecting osmosis. They are soluble in the solution within a cell, or in the surrounding fluid, e.g. as plasma osmolytes. They play a role in maintaining cell volume and fluid balance. For example, when a cell swells due to external osmotic pressure, membrane channels open...
- Myo-InositolInositolInositol or cyclohexane-1,2,3,4,5,6-hexol is a chemical compound with formula 6126 or 6, a sixfold alcohol of cyclohexane. It exists in nine possible stereoisomers, of which the most prominent form, widely occurring in nature, is cis-1,2,3,5-trans-4,6-cyclohexanehexol, or myo-inositol...
- Taurine and Taurine-transporting ATPaseTaurine-transporting ATPaseIn enzymology, a taurine-transporting ATPase is an enzyme that catalyzes the chemical reactionThe 3 substrates of this enzyme are ATP, H2O, and taurine, whereas its 3 products are ADP, phosphate, and taurine....
- CreatineCreatineCreatine is a nitrogenous organic acid that occurs naturally in vertebrates and helps to supply energy to all cells in the body, primarily muscle. This is achieved by increasing the formation of Adenosine triphosphate...
- BetainesBetainesA betaine in chemistry is any neutral chemical compound with a positively charged cationic functional group such as an quaternary ammonium or phosphonium cation which bears no hydrogen atom and with a negatively charged functional group such as a carboxylate group which may not be adjacent to the...
- TrimethylglycineTrimethylglycineTrimethylglycine is an organic compound that occurs in plants as either glycine betaine or a choline-containing glycine betaine compound. Trimethylglycine was the first betaine discovered by science; originally it was simply called betaine because, in the 19th century, it was discovered in sugar...
- A Betaine and metabolite of CholineCholineCholine is a water-soluble essential nutrient. It is usually grouped within the B-complex vitamins. Choline generally refers to the various quaternary ammonium salts containing the N,N,N-trimethylethanolammonium cation.... - SorbitolSorbitolSorbitol, also known as glucitol, Sorbogem® and Sorbo®, is a sugar alcohol that the human body metabolizes slowly. It can be obtained by reduction of glucose, changing the aldehyde group to a hydroxyl group. Sorbitol is found in apples, pears, peaches, and prunes...
- Glycerophosphocholine