Big endothelin-1(1-39) (RAT) is a 39 amino acid peptide, which is synthesized and secreted by vascular smooth muscle and endothelium cells. It is produced as an inactive enzyme, and is cleaved and activated by serine and aspartic proteases and metalloproteinases. Activated form is called ET-1, which is a potent vasoconstrictor. ET-1 is also produced by the action of endothelin converting enzyme (ECE) on big-ET-1. In guinea pigs, big-ET-1 causes the release of prostanoids and thromboxanes.
