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Histamine binding to endothelial cells causes them to contract, thus increasing vascular leak. It also stimulates synthesis and release of various vascular smooth muscle cell relaxants, such as nitric oxide, endothelium-derived hyperpolarizing factors and other compounds, resulting in blood vessel dilation. [31]
A mast cell (also known as a mastocyte or a labrocyte [1]) is a resident cell of connective tissue that contains many granules rich in histamine and heparin.Specifically, it is a type of granulocyte derived from the myeloid stem cell that is a part of the immune and neuroimmune systems.
Vasodilation plays a major role in immune system function. Wider blood vessels allow more blood containing immune cells and proteins to reach the infection site. Vasodilation occurs as part of the process of inflammation, which is caused by several factors including presence of a pathogen, injury to tissues or blood vessels, and immune ...
The H 1 receptor is a histamine receptor belonging to the family of rhodopsin-like G-protein-coupled receptors.This receptor is activated by the biogenic amine histamine.It is expressed in smooth muscles, on vascular endothelial cells, in the heart, and in the central nervous system.
These endothelial products include nitric oxide and endothelin-1 that are released in response to either chemical stimuli, like histamine, or increased shear stress on the blood vessel (meaning the amount of stress exerted by blood on the blood vessel walls). While nitric oxide causes vasodilation, endothelin-1 causes vasoconstriction.
The histamine receptors are a class of G protein ... and H4 to immune system function. There are four known histamine receptors: ... (cells of walls of blood vessels ...
Histamine is an important biogenic amine that moderates numerous physiologic processes. There are four different histamine receptors, H 1, H 2, H 3, and H 4, [16] each of which carries a different biological significance. H 1 modulates several functions of the central and peripheral nervous system, including circadian rhythm, body temperature ...
When activated, mast cells rapidly release characteristic granules, rich in histamine and heparin, along with various hormonal mediators and chemokines, or chemotactic cytokines into the environment. Histamine dilates blood vessels, causing the characteristic signs of inflammation, and recruits neutrophils and macrophages. [5]