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Time dependent conversion of creatine kinase MM isoforms in man
T Kojima1, H Hashimoto, H Tsukamoto
1Second Department of Internal Medicine, Nagoya University School of Medicine, Japan.
Cardiovascular Research
|June 1, 1987
Summary
Creatine kinase MM isoforms (MMA, MMB, MMC) change over time after myocardial infarction. Analyzing these serum creatine kinase isoforms can help precisely date the onset of heart attacks and aid in prompt diagnosis.
Area of Science:
- Biochemistry
- Cardiology
- Clinical Chemistry
Background:
- Creatine kinase MM isoenzymes exist in subforms (isoforms) with distinct isoelectric points: MMA, MMB, and MMC.
- MMA is the dominant isoform in normal and infarcted human myocardium.
Purpose of the Study:
- To quantify creatine kinase MM isoforms in human myocardium and serum.
- To investigate the in vitro and in vivo conversion of creatine kinase MM isoforms.
- To assess the potential of serum isoform analysis for dating acute myocardial infarction.
Main Methods:
- Quantification of creatine kinase MM isoforms using chromatofocusing.
- In vitro incubation of partially purified MMA with human plasma.
- Analysis of serum isoforms in patients with acute myocardial infarction at different time points.
Main Results:
- In vitro, MMA was rapidly converted to MMB and MMC in human plasma.
- In vivo, serum isoform proportions shifted sequentially from MMA-dominant to MMB-dominant, then to MMC-dominant in patients with acute myocardial infarction.
- Isoform conversion velocity in humans was slower than in dogs.
Conclusions:
- Serum creatine kinase MM isoform analysis provides a time-dependent profile following myocardial infarction.
- This analysis can precisely date the onset of acute myocardial infarction.
- Determination of MMA may be valuable for the early diagnosis of myocardial infarction.