DIFFERENT RESPONSE OF CELLULAR DNA CONTENT TO CARDIAC-HYPERTROPHY IN HUMAN AND RAT-HEART MYOCYTES

1. 1. Rat and human heart myocytes adapt to overload-induced hypertrophy differently. 2. 2. Human myocyte nuclei respond with polyploidization and multinucleation, thus increasing the DNA content per myocyte from 20 to 40 pg. As a result, nuclear DNA content per 10,000 μm3 of cell volume decreases from 12 to 10 pg. 3. 3. In rat hearts with aortic constriction nuclear DNA content remains constant (13 pg), and the DNA content per 10,000 μm3 of myocyte volume falls from 9 to 6 pg. 4. 4. We hypothesize that "dilution" of nuclear DNA in the hypertrophied rat heart myocyte limits the capacity to hypertrophy (≪100%). 5. 5. The human heart myocyte, which is able to compensate for dilution of nuclear DNA, may increase in size more than three-fold. 6. 6. The lower limit of DNA content per unit of myocyte volume is 6pg/10,000 μm3 in both species. © 1989.