Human Endothelin are peptides which function in blood vessel constriction and increase the blood pressure. These human endothelin’s are kept under balance and in check by other mechanisms. Overexpression of human endothelin’s lead to hypertension or high blood pressure and heart diseases. Human endothelin’s functioning as vasoconstrictor, in their elevated levels result in sodium retention and renal vasoconstriction. This leads to hepatorenal syndrome, heart failure, or renal failure. Endothelin 1 belongs to the endothelin family which are 21 amino acids peptides. Three isoforms of endothelin are described they are, ET-1, ET-2 and ET-3. ET-1 or endothelin-1 is the most predominant isoform associated with the pathological effects in the cardiovascular system. Endothelin-1 is formed in very small amounts under physiological condition, but its production is stimulated and elevated under pathophysiological conditions. The endothelin-1 is majorly produced by endothelium and has a vital role in vascular homeostasis. Secretion of endothelin-1 leads to signalling of vasoconstriction which further influences the survival and cellular growth locally. Studies have also shown that human endothelin 1 derived from the arterial cells are also involved in advancement of atherosclerosis. The receptors of both Endothelin-1 and endothelin are upregulated in both animals and humans with atherosclerotic lesions. 

Experiments show a polar secretion of endothelin-1 by the endothelial cells. They are secreted in the basal side direction of the vessels. It is also shown that endothelin-1 secretion in a polarized pattern is enhanced in the presence of LDL and inhibited in the presence of HDL. Upregulation of endothelin-1 is usually observed in response to bacterial toxins, hypoxia and oxidized LDL.