Does aortic constriction alter DNA content, polyploidy, and mitotic activity in the left ventricle of rats?
Cardiac hypertrophy induced by aortic constriction in rats is associated with proportional increases in DNA content, increased polyploidy, and significantly higher mitotic activity primarily outside muscle cells.
DNA concentration in the left ventricle of 3-month-old rats 3 to 12 days after aortic constriction was similar to the values obtained in sham-operated litter mates (1.38 ± 0.03 µg/mg wet weight). The total DNA content of the heart was thus increased proportionally to its enlargement. In chronic hypertrophy (2 to 4 months after aortic constriction), the DNA content was increased to a significantly less extent than in short-term hypertrophy. The percentage of polyploid nuclei in 12- to 13-week-old rats increased 1 to 3 weeks after aortic constriction from a normal value of 1.8% to 4.2%. In 17- to 18-week-old rats, polyploidy was present in 3.9% of the nuclei 10 days after banding as compared with 1.6% in normal rats. Mitotic figures were localized almost exclusively outside muscle cells. Mitotic indices in hypertrophied hearts were ten times higher than in controls during the first 3 weeks after aortic constriction.
Grove et al. (Wed,) studied this question.