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AgNORs in cardiomyocytes from surgical patients with coronary heart disease
N N Mamaev1, O V Kovalyeva, Kh K Amineva
1Department of Internal Medicine I, Pavlov Medical University of St Petersburg, Russia.
Insights
The nucleolar organiser region silver staining (AgNOR) technique effectively measures cardiomyocyte ribosomal RNA cistron activity in heart disease patients. This sensitive test monitors cardiac function during surgery, especially after cardioplegia and reperfusion.
Area of Science:
- Cardiovascular Science
- Molecular Biology
- Surgical Research
Background:
- Chronic ischaemic heart disease poses significant surgical risks.
- Assessing cardiomyocyte function during cardiac surgery is crucial for patient outcomes.
- The nucleolar organiser region silver staining (AgNOR) technique offers a potential method for evaluating cellular activity.
Purpose of the Study:
- To evaluate interphase ribosomal RNA cistron activity in cardiomyocytes of surgical patients with chronic ischaemic heart disease.
- To assess the utility of the AgNOR technique for monitoring myocardial status during cardioplegia and reperfusion.
Main Methods:
- Myocardial samples from 46 patients with chronic ischaemic heart disease were analyzed before, during, and after cardioplegia.
- The AgNOR technique was employed to quantify silver-stained nucleoli in cardiomyocyte and fibroblast nuclei.
- Statistical analysis, including the Student's t test, was used to compare AgNOR counts between different stages and patient groups.
Main Results:
- Initial AgNOR counts varied, with significant differences observed between patients with and without prior myocardial infarction (p < 0.05).
- During myocardial arrest, cardiomyocyte AgNOR counts decreased, while fibroblast AgNOR counts tended to increase.
- Following reperfusion, cardiomyocyte AgNOR counts normalized or increased, indicating a dynamic response to ischemia and reoxygenation.
Conclusions:
- The AgNOR count in cardiomyocytes is a sensitive indicator of cardiac function in surgical patients with chronic ischaemic heart disease.
- This technique can be valuable for monitoring myocardial status throughout cardiac surgery, particularly during cardioplegia.
- Patients with antecedent myocardial infarction and severe heart failure represent a high-risk surgical group, potentially reflected in AgNOR count dynamics.
Aim:
To evaluate the interphase ribosomal RNA cistron activity of cardiomyocytes in surgical patients with chronic ischaemic heart disease by means of the nucleolar organiser region silver staining (AgNOR) technique.
Methods:
Nucleoli were investigated in myocardial samples obtained from 46 patients with chronic ischaemic heart disease before, during, and soon after cardioplegia ischaemia. Cryostat sections of 10 microns thickness were air dried, fixed in methanol/glacial acetic acid (3:1) for 15 minutes, rinsed carefully with distilled water, incubated in 2 N formic acid for 10 minutes, and impregnated with silver colloid solution for 2.5-3 minutes at 68-70 degrees C. The lightly counterstained sections were examined under oil immersion at x1000 magnification. For the estimation of AgNOR numbers at least 100 silver stained cardiomyocyte and fibroblast nuclei were counted in each section. On the basis of these data, the mean number of AgNORs in each nucleus was determined. The Student's t test was used to compare the groups tested.
Results:
The initial mean numbers of AgNORs varied greatly, demonstrating a difference between groups of patients with or without antecedent myocardial infarction (9.5 v 11.0; p < 0.05). During myocardial arrest, the numbers of AgNORs in cardiomyocytes were decreased in all but seven patients, while those in fibroblasts tended to increase. At the stage of reperfusion and myocardial warming, in all but three patients the numbers of AgNORs in cardiomyocytes either normalised or were even higher than the initial value.
Conclusions:
The AgNOR count in cardiomyocytes is a very sensitive test for the measurement of cardiac function in surgical patients with chronic ischaemic heart disease and could be useful for monitoring myocardial status during the course of surgery, including cardioplegia. The high risk group for surgery included patients with antecedent myocardial infarction and severe heart failure. It is thought that a reversible nucleolin/fibrillarin/pre-rRNA/small nucleolar RNA modification might account for this fast decline then rise in the AgNOR count in cardiomyocytes at the stages of cardioplegia and reperfusion, respectively.