<P> First cTnI. and later cTnT were used as markers of cardiac cell death . Now both proteins are widely used for the diagnosis of acute myocardial infarction (AMI), unstable angina, post-surgery myocardium trauma and some other diseases related with cardiac muscle injury . Both markers can be detected in patient's blood 3--6 hours after onset of the chest pain, reaching peak level within 16--30 hours . Elevated concentration of cTnI and cTnT in blood samples can be detected even 5--8 days after onset of the symptoms, making both proteins useful also for the late diagnosis of AMI . </P> <P> Cardiac troponin T and I are measured by immunoassay methods . </P> <Ul> <Li> Due to patent regulations, a single manufacturer (Roche Diagnostics) distributes cTnT . </Li> <Li> A host of diagnostic companies make cTnI immunoassay methods available on many different immunoassay platforms . </Li> </Ul> <Li> Due to patent regulations, a single manufacturer (Roche Diagnostics) distributes cTnT . </Li>

Ions from the sarcoplasmic reticulum inhibits the activity of troponin