1. What is Endothelin-1 (ET-1)? Endothelin-1 (ET-1) is one of the most potent vasoconstrictors in the body, primarily produced by endothelial cells, podocytes, and tubular cells in the kidney. ET-1 binds to endothelin A (ETA)… Endothelin-1 and IgA Nephropathy : Therapeutic Approache