The sensitive measurement of total rat tPA antigen is easily performed with this 96 well strip format ELISA kit. tPA binds to the capture antibody coated on the microtiter plate. Free and complexed tPA will bind to the capture antibody. An HRP detection system using TMB substrate is used for color development at 450 nm. A standard calibration curve is prepared using dilutions of purified tPA and is measured along with the test samples.