Euler-Liljestrand mechanism
Encyclopedia
The Euler–Liljestrand mechanism describes the connection between ventilation
and blood circulation (perfusion
) of the lung
. If the ventilation in a part of the lung decreases, this leads to local hypoxia
and to vasoconstriction
in that part. This adaptive mechanism is beneficial, because it diminishes the amount of blood
that passes the lung without being oxygenated
. The mechanism was discovered by two Swedish
pharmacologists, Ulf von Euler
and Göran Liljestrand
at the Department of Pharmacology of Karolinska Institute in Stockholm
.
The molecular mechanism seems to be mediated by oxygen
-sensitive potassium
ion channel
s in the cell membrane
of pulmonary smooth muscle
. With a low partial pressure of oxygen, these channels are blocked, leading to the depolarization of the cell membrane. Calcium
channels are activated and cause the influx of Ca2+ ions over the membrane and to the release of calcium
from the endoplasmic reticulum
. The rise of calcium concentration causes contraction of the blood vessels smooth muscle fibers and the resulting vasoconstriction
. Histamine
has also been implicated in this mechanism.
Ventilation (physiology)
In respiratory physiology, ventilation is the rate at which gas enters or leaves the lung. It is categorized under the following definitions:-Sample values:...
and blood circulation (perfusion
Perfusion
In physiology, perfusion is the process of nutritive delivery of arterial blood to a capillary bed in the biological tissue. The word is derived from the French verb "perfuser" meaning to "pour over or through."...
) of the lung
Lung
The lung is the essential respiration organ in many air-breathing animals, including most tetrapods, a few fish and a few snails. In mammals and the more complex life forms, the two lungs are located near the backbone on either side of the heart...
. If the ventilation in a part of the lung decreases, this leads to local hypoxia
Hypoxia (medical)
Hypoxia, or hypoxiation, is a pathological condition in which the body as a whole or a region of the body is deprived of adequate oxygen supply. Variations in arterial oxygen concentrations can be part of the normal physiology, for example, during strenuous physical exercise...
and to vasoconstriction
Vasoconstriction
Vasoconstriction is the narrowing of the blood vessels resulting from contraction of the muscular wall of the vessels, particularly the large arteries, small arterioles and veins. The process is the opposite of vasodilation, the widening of blood vessels. The process is particularly important in...
in that part. This adaptive mechanism is beneficial, because it diminishes the amount of blood
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....
that passes the lung without being oxygenated
Oxygen saturation
Oxygen saturation or dissolved oxygen is a relative measure of the amount of oxygen that is dissolved or carried in a given medium. It can be measured with a dissolved oxygen probe such as an oxygen sensor or an optode in liquid media, usually water.It has particular significance in medicine and...
. The mechanism was discovered by two Swedish
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....
pharmacologists, Ulf von Euler
Ulf von Euler
Ulf Svante von Euler was a Swedish physiologist and pharmacologist. He won a Nobel Prize in Physiology or Medicine in 1970 for his work on neurotransmitters.-Life:...
and Göran Liljestrand
Göran Liljestrand
Göran Liljestrand , Swedish pharmacologist, known for the discovery of the Euler-Liljestrand mechanism.Liljestrand was born in Gothenburg but finished school at the Norra Real school in Stockholm, before matriculating at the University College of Stockholm in 1904...
at the Department of Pharmacology of Karolinska Institute in Stockholm
Stockholm
Stockholm is the capital and the largest city of Sweden and constitutes the most populated urban area in Scandinavia. Stockholm is the most populous city in Sweden, with a population of 851,155 in the municipality , 1.37 million in the urban area , and around 2.1 million in the metropolitan area...
.
The molecular mechanism seems to be mediated by oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
-sensitive potassium
Potassium
Potassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...
ion channel
Ion channel
Ion channels are pore-forming proteins that help establish and control the small voltage gradient across the plasma membrane of cells by allowing the flow of ions down their electrochemical gradient. They are present in the membranes that surround all biological cells...
s in the 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...
of pulmonary smooth muscle
Smooth muscle
Smooth muscle is an involuntary non-striated muscle. It is divided into two sub-groups; the single-unit and multiunit smooth muscle. Within single-unit smooth muscle tissues, the autonomic nervous system innervates a single cell within a sheet or bundle and the action potential is propagated by...
. With a low partial pressure of oxygen, these channels are blocked, leading to the depolarization of the cell membrane. Calcium
Calcium
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...
channels are activated and cause the influx of Ca2+ ions over the membrane and to the release of calcium
Calcium
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...
from the endoplasmic reticulum
Endoplasmic reticulum
The endoplasmic reticulum is an organelle of cells in eukaryotic organisms that forms an interconnected network of tubules, vesicles, and cisternae...
. The rise of calcium concentration causes contraction of the blood vessels smooth muscle fibers and the resulting vasoconstriction
Vasoconstriction
Vasoconstriction is the narrowing of the blood vessels resulting from contraction of the muscular wall of the vessels, particularly the large arteries, small arterioles and veins. The process is the opposite of vasodilation, the widening of blood vessels. The process is particularly important in...
. Histamine
Histamine
Histamine is an organic nitrogen compound involved in local immune responses as well as regulating physiological function in the gut and acting as a neurotransmitter. Histamine triggers the inflammatory response. As part of an immune response to foreign pathogens, histamine is produced by...
has also been implicated in this mechanism.