Vascular permeability, often in the form of capillary permeability or microvascular permeability, characterizes the
permeability of a
blood vessel
Blood vessels are the tubular structures of a circulatory system that transport blood throughout many Animal, animals’ bodies. Blood vessels transport blood cells, nutrients, and oxygen to most of the Tissue (biology), tissues of a Body (bi ...
wall–in other words, the blood vessel wall's capacity to allow for the flow of small
molecules
A molecule is a group of two or more atoms that are held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions that satisfy this criterion. In quantum physics, organic chemistry ...
(such as drugs,
nutrients
A nutrient is a substance used by an organism to survive, grow and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi and protists. Nutrients can be incorporated into cells for metabolic purposes or excret ...
, water, or
ions
An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...
) or even whole
cells (such as
lymphocyte
A lymphocyte is a type of white blood cell (leukocyte) in the immune system of most vertebrates. Lymphocytes include T cells (for cell-mediated and cytotoxic adaptive immunity), B cells (for humoral, antibody-driven adaptive immunity), an ...
s on their way to a site of
inflammation
Inflammation (from ) is part of the biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. The five cardinal signs are heat, pain, redness, swelling, and loss of function (Latin ''calor'', '' ...
) in and out of the vessel.
Blood vessel
Blood vessels are the tubular structures of a circulatory system that transport blood throughout many Animal, animals’ bodies. Blood vessels transport blood cells, nutrients, and oxygen to most of the Tissue (biology), tissues of a Body (bi ...
walls are lined by a single layer of
endothelial cells. The gaps between endothelial cells (
cell junction
Cell junctions or junctional complexes are a class of cellular structures consisting of multiprotein complexes that provide contact or adhesion between neighboring Cell (biology), cells or between a cell and the extracellular matrix in animals. Th ...
s) are strictly regulated depending on the type and
physiological
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 ...
state of the
tissue.
There are several techniques to measure vascular permeability to certain molecules. For instance, the
cannulation of a single
microvessel
The microcirculation is the circulatory system, circulation of the blood in the smallest blood vessels, the microvessels of the microvasculature present within organ (anatomy), organ Tissue (biology), tissues. The microvessels include terminal ar ...
with a
micropipette: the microvessel is perfused with a certain pressure, occluded downstream, and then the velocity of some cells will be related to the permeability.
[Michel, C. C., Mason, J. C., Curry, F. E. & Tooke, J. E. Development of Landis Technique for Measuring Filtration Coefficient of Individual Capillaries in Frog Mesentery. Q J Exp Physiol Cms 59, 283-309 (1974).][Bates, D. O. & Harper, S. J. Regulation of vascular permeability by vascular endothelial growth factors. Vascul Pharmacol 39, 225-237 (2002)] Another technique uses multiphoton fluorescence
intravital microscopy through which the flow is related to fluorescence intensity and the permeability is estimated from the Patlak transformation.
[Patlak, C. S., Blasberg, R. G. & Fenstermacher, J. D. Graphical evaluation of blood-to-brain transfer constants from multiple-time uptake data. J Cereb Blood Flow Metab 3, 1-7 (1983).]
An example of increased vascular permeability is in the
initial lesion of periodontal disease, in which the
gingival plexus becomes engorged and
dilated, allowing large numbers of
neutrophil
Neutrophils are a type of phagocytic white blood cell and part of innate immunity. More specifically, they form the most abundant type of granulocytes and make up 40% to 70% of all white blood cells in humans. Their functions vary in differe ...
s to
extravasate and appear within the
junctional epithelium and underlying
connective tissue
Connective tissue is one of the four primary types of animal tissue, a group of cells that are similar in structure, along with epithelial tissue, muscle tissue, and nervous tissue. It develops mostly from the mesenchyme, derived from the mesod ...
.
[Page, RC; Schroeder, HE. "Pathogenesis of Inflammatory Periodontal Disease: A Summary of Current Work." ''Lab Invest'' 1976;34(3):235-249]
See also
*
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 ...
References
External links
* {{MeshName, Vascular+Permeability
Cardiovascular physiology