Endothelins (ET's) are the most potent vasoconstrictors known [ PUBMED:2690429 PUBMED:2168326 PUBMED:1916094 ]. They stimulate cardiac contraction, regulate release … expand

Endothelins (ET's) are the most potent vasoconstrictors known [ PUBMED:2690429 PUBMED:2168326 PUBMED:1916094 ]. They stimulate cardiac contraction, regulate release of vasoactive substances, and stimulate mitogenesis in blood vessels in primary culture. They also stimulate contraction in almost all other smooth muscles (e.g., uterus, bronchus, vas deferensa and stomach) and stimulate secretion in several tissues (e.g., kidney, liver and adrenals). Endothelin receptors have also been found in the brain, e.g. cerebral cortex, cerebellum and glial cells. Endothelins have been implicated in a variety of pathophysiological conditions associated with stress, including hypertension, myocardial infarction, subarachnoid haemorrhage and renal failure.

Endothelins are synthesised by proteolysis of large preproendothelins, which are cleaved to 'big endothelins' before being processed to the mature peptide.

Sarafotoxins (SRTX) and bibrotoxin (BTX) are cardiotoxins from the venom of snakes of the Atractaspis family, structurally and functionally [ PUBMED:2549664 PUBMED:1656557 ] similar to endothelin.

As shown in the following schematic representation, these peptides which are 21 residues long contain two intramolecular disulphide bonds.

 +-------------+ | | CxCxxxxxxxCxxxCxxxxxx | | +-------+'C': conserved cysteine involved in a disulphide bond.

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