T-1824 or Evans blue, often incorrectly rendered as Evan's blue, is an

azo dye Azo dyes are organic compounds bearing the functional group R−N=N−R′, in which R and R′ are usually aryl and substituted aryl groups. They are a commercially important family of azo compounds, i.e. compounds containing the C−N=N−C l ...

that has a very high affinity for

serum albumin Serum albumin, often referred to simply as blood albumin, is an albumin (a type of globular protein) found in vertebrate blood. Human serum albumin is encoded by the ''ALB'' gene. Other mammalian forms, such as bovine serum albumin, are chem ...

. Because of this, it can be useful in

physiology Physiology (; ) is the science, scientific study of function (biology), functions and mechanism (biology), mechanisms in a life, living system. As a branches of science, subdiscipline of biology, physiology focuses on how organisms, organ syst ...

in estimating the proportion of

body water In physiology, body water is the water content of an animal body that is contained in the tissues, the blood, the bones and elsewhere. The percentages of body water contained in various fluid compartments add up to total body water (TBW). This ...

contained in

blood plasma Blood plasma is a light Amber (color), amber-colored liquid component of blood in which blood cells are absent, but which contains Blood protein, proteins and other constituents of whole blood in Suspension (chemistry), suspension. It makes up ...

. It fluoresces with excitation peaks at 470 and 540 nm and an emission peak at 680 nm. Evans blue dye has been used as a

viability assay A viability assay is an assay that is created to determine the ability of organs, cells or tissues to maintain or recover a state of survival. Viability can be distinguished from the all-or-nothing states of life and death by the use of a quanti ...

on the basis of its penetration into non-viable cells, although the method is subject to error because it assumes that damaged or otherwise altered cells are not capable of repair and therefore are not viable. Evans blue is also used to assess the permeability of the

blood–brain barrier The blood–brain barrier (BBB) is a highly selective semipermeable membrane, semipermeable border of endothelium, endothelial cells that regulates the transfer of solutes and chemicals between the circulatory system and the central nervous system ...

to macromolecules. Because serum albumin cannot cross the barrier and virtually all Evans blue is bound to albumin, normally the neural tissue remains unstained. When the blood–brain barrier has been compromised, albumin-bound Evans blue enters the CNS. Evans blue is pharmacologically active, acting as a

negative allosteric modulator In pharmacology and biochemistry, allosteric modulators are a group of substances that bind to a receptor to change that receptor's response to stimuli. Some of them, like benzodiazepines or alcohol, function as psychoactive drugs. The site that a ...

of the

AMPA α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, better known as AMPA, is a compound that is a specific agonist for the AMPA receptor, where it mimics the effects of the neurotransmitter glutamate Glutamic acid (symbol Glu or E; kn ...

and

kainate receptor Kainate receptors, or kainic acid receptors (KARs), are ionotropic receptors that respond to the neurotransmitter glutamate. They were first identified as a distinct receptor type through their selective activation by the agonist kainate, a dr ...

s and as an

inhibitor Inhibitor or inhibition may refer to: Biology * Enzyme inhibitor, a substance that binds to an enzyme and decreases the enzyme's activity * Reuptake inhibitor, a substance that increases neurotransmission by blocking the reuptake of a neurotransmi ...

vesicular glutamate transporter Vesicular glutamate transporter 1 (VGLUT1) is a protein that in humans is encoded by the ''SLC17A7'' gene. The protein encoded by this gene is a vesicle-bound, sodium-dependent phosphate transporter that is specifically expressed in the neuron-r ...

s. It also acts on

P2 receptor P2 receptor may refer to: Nucleotides, if released into the extracellular environment, can lead to cell death or other harmful cellular consequences. To avoid cellular damage, nucleotides should be neutralized, which is accomplished by P2 receptors ...

s. It was named after

Herbert McLean Evans Herbert McLean Evans (September 23, 1882 – March 6, 1971) was an American anatomist and embryologist best known for co-discovering Vitamin E. Education He was born in Modesto, California. In 1908, he obtained his medical degree from Johns Hop ...

, an American anatomist.

References

External links

* {{Purine receptor modulators AMPA receptor antagonists Azo dyes Kainate receptor antagonists Naphthalenesulfonates Naphthylamines Negative allosteric modulators