The Eagle Biosciences Rat Anti Endothelin Receptor A IgG Antibody ELISA Assay Kit is an antibody screening test. Endothelin- receptor A has been pre-coated onto a microtiter plate. During the first incubation the anti-Endothelin receptor A-The Eagle Biosciences Rat Anti Endothelin Receptor A IgM Antibody ELISA Assay Kit is an antibody screening test. Endothelin- receptor A has been pre-coated onto a microtiter plate. During the first incubation the anti-Endothelin receptor A-IgM-Antibodies of the samples are immobilized on the plate. The autoantibodies are detected with a POD labelled anti-Rat IgM antibody. In the following enzymatic substrate reaction the intensity of the colour correlates with the concentration and/ or avidity of anti-Endothelin receptor A-IgM-antibody (Rat). Sample Types: serum, plasma. Range: 1.25 -40 U/ml. Sensitivity: Cut-off. Time: 3.5 hours ? Endothelins (ET) are 21-amino acid vasoconstricting peptides produced primarily in the endothelium having a key role in vascular homeostasis. It mediates the effects through G-Protein-coupled receptors, the Endothelin receptors. There are two key receptor types, ETA and ETB. ETA receptors are found in the smooth muscle tissue of blood vessels where they increase vasoconstriction by ET-1. The Eagle Biosciences Rat Anti Endothelin Receptor A IgM Antibody is designed for the determination of antibodies (IgM) against the Endothelin receptor subtype A in serum and plasma.