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Enzyme activities of human myocardium: creatine kinase and hexose phosphate isomerase
Insights
This study measured creatine kinase (CK) and hexose phosphate isomerase (PHI) in human heart muscle. Enzyme activities were notably high, particularly CK, and significantly correlated, suggesting clinical and metabolic importance.
Area of Science:
- Biochemistry
- Cardiology
- Human Physiology
Background:
- Creatine kinase (CK) and hexose phosphate isomerase (PHI) are key enzymes in cellular energy metabolism.
- Understanding their activity in human heart muscle is crucial for diagnosing cardiac conditions and understanding myocardial function.
Purpose of the Study:
- To quantify creatine kinase (CK) and hexose phosphate isomerase (PHI) activities in human heart muscle samples.
- To compare these activities with previously reported values and with those in skeletal muscle.
- To investigate the correlation between CK and PHI activities and discuss their clinical and metabolic significance.
Main Methods:
- Enzyme activity assays for CK and PHI were performed on 36 human heart muscle samples.
- Samples were obtained from patients undergoing cardiovascular surgery.
- Statistical analysis was used to determine correlations between enzyme activities.
Main Results:
- Creatine kinase (CK) activities were exceptionally high in human heart muscle, exceeding previously reported levels.
- Hexose phosphate isomerase (PHI) activities were comparable to those found in skeletal muscle, with higher levels in papillary muscle.
- A significant positive correlation (r = 0.773, p < 0.001) was observed between CK and PHI activities across all samples.
Conclusions:
- The elevated CK and PHI activities in human heart muscle suggest a high metabolic demand and potential clinical relevance.
- The significant correlation between these enzymes may indicate coordinated roles in myocardial energy metabolism.
- Further research is warranted to explore the clinical applications and detailed metabolic implications of these findings.
Abstract:
Creatine kinase (CK) and hexose phosphate isomerase (PHI) activities were determined in 36 samples of human heart muscle obtained from patients during cardiovascular surgery. With one exception, CK activities were higher than any reported so far in the literature (papillary muscle, left ventricle: 2,521 +/- 776 IU/g wet weight at 37 degrees C). PHI Activities, the first time measured, are comparable to those in skeletal muscle (200-400 U/g, higher in papillary muscle than in the right auricle). The activities of both enzymes determined correlate significantly (all samples considered together: r = 0.773; p < 0.001). Results are discussed with respect to their possible clinical interest as well as their significance for myocardial metabolism.