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A correlation between the structure of myocardial cells and prolonged Q-T interval in young rats
1Department of Physiology, Sackler School of Medicine, Tel-Aviv University Ramat-Aviv, Israel.
Insights
Persistent Q-T prolongation in young rats correlates with undifferentiated myocardial cells. This finding suggests a link between delayed myocyte differentiation and electrocardiogram abnormalities in developing hearts.
Area of Science:
- Cardiology
- Developmental Biology
- Histology
Background:
- The Q-T interval in electrocardiograms (ECG) reflects ventricular repolarization.
- Normal development involves Q-T interval shortening with age.
- Abnormalities in myocardial differentiation can impact cardiac function.
Purpose of the Study:
- To investigate the relationship between electrocardiogram (ECG) findings and myocardial histology in young rats.
- To identify potential cellular mechanisms underlying Q-T interval prolongation in neonatal and juvenile rats.
Main Methods:
- Electrocardiograms were recorded from rat offspring at various postnatal ages.
- Heart tissues were microscopically examined for myocardial cell differentiation.
- Correlation analysis was performed between ECG parameters and histological findings.
Main Results:
- A subset of newborns exhibited prolonged Q-T intervals on ECG.
- Persistent Q-T prolongation was associated with delayed histological differentiation of the myocardium.
- Undifferentiated myoblasts were significantly more prevalent in rats with prolonged Q-T intervals compared to those with normal intervals (r = 0.9).
Conclusions:
- Persistence of undifferentiated myoblasts is strongly correlated with prolonged Q-T intervals in developing rat hearts.
- These findings suggest that impaired myocyte differentiation may contribute to Q-T prolongation.
- Examination of myocardial differentiation in patients with prolonged Q-T syndrome could have clinical relevance.
Abstract:
In the present study, we examined the electrocardiogram and the structure of myocardial cells in young rats at different postnatal ages. The offspring of rats were sacrificed on different postnatal days following electrocardiographical recordings, and sections of their hearts were examined microscopically. In a number of newborns, we observed definite prolongation of the Q-T interval in the electrocardiogram on the first day of life. Normal shortening of the Q-T interval with age was demonstrated in the majority of the offspring while, in some of them, the Q-T interval remained prolonged. In the "affected" offspring, which exhibit a typical pattern of Q-T prolongation with clear ST segment, definite retardation of histological differentiation of the myocardium was found at various ages. In these cases, there were large numbers of "myoblasts" scattered between normal myocytes in different parts of the ventricular walls and septum. These myoblasts were rarely identified in newborns and offspring with a normal Q-T interval. Our results clearly show a correlation between the ratio of persistence of undifferentiated myoblasts at any age and the typical prolonged Q-T pattern in the electrocardiogram (r = 0.9). Due to the possible clinical significance, the hearts of patients with prolonged Q-T syndrome should be examined so as to reach for abnormal differentiation of the myocytes.