2. Creatine kinase and myocardial infarction Flashcards
What is creatine kinase responsible for?
Catalysing the conversion of:
CREATINE PHOSPHATE to CREATINE
Generates1 ATP is generated in this reaction
In what tissues is Creatine Kinase present at high levels?
Muscles (MM creatine kinase)
Brain (BB creatine kinase)
What type of creatine kinase is present in the myocardium?
BM creatine kinase
When and why is CK found in the blood?
Damage to the cell membrane allows leakage of CK into the blood stream.
What causes the plasma membrane of myocardial cells to become leaky?
Active transport membrane proteins (pumps) stop working because they require ATP to function.
High concentrations of everything inside the cells leaks out.
How might you determine CK activity?
Creatine and Creatine Phosphate is not easily detectable
so COUPLED ASSAYS are used
What is a coupled assay?
Use of 2 or more reactions to find something detectable e.g. NADPH absorbs UV light
How might one establish a diagnosis of myocardial damage?
Elevated levels of MB creatine kinase in the serum.
Does an increase in serum CK activity relate to the size of myocardial damage?
Yes
Levels of CK BM isoform in the serum are directly proportional to the amount of cell death in the heart. Each myocyte has a set amount of CK so when more cells are damaged, there is more CK.
What is the time course of serum CK after a myocardial infarction?
30 mins to 2.5 days
What other markers can be used for diagnosis of myocardial damage?
LDH: leaks when cells are damaged. Not particularly specific, only peaks after 6 days.
Troponin: elevated levels of Troponin I and T which are specific to cardiac muscle (appears after 48 hours and lasts 5 days).
Serum Glutamate Oxaloacetate Transaminase (SGOT): starts being released from cells. Peaks as CK goes down.
