A Method for Determining Deoxyribonucleic Acid Synthetic Time and Mitotic Time of Heart Muscle by Autoradiographic Technique

A new method to estimate the DNA synthetic time and mitotic time of heart muscle of rats from single autoradiographic specimen was described. If the postsynthetic time is negligible, the DNA synthetic time of heart muscle cells is 15-16 hours in 2-day-old, 1- and 2-week-old rats. The mitotic time of heart muscle cells is 7-11 hours. The DNA synthetic time of interstitial cells is 15-18 hours in 2-day, 1-, 2- and 3-week-old rats. The mitotic time of interstitial cells is 7-9 hours. The DNA synthetic time was also calculated from the estimation of cell number and the results were compared with the above mentioned values. In addition, a method to approach the postsynthetic time was mentioned.