Abstract
DNA synthesis of pancreatic islet cells of 6-8 wk-old rats was examined during a 14day-culture period by autoradiography using 3H-thymidine. Pancreatic islets were isolated from rats by collagenase and dispersed into single cells with EDTA and Dispase. The dispersed islet cells or isolated islets were cultured in a Microplate and the DNA synthesizing capacity (labeling index) of islet beta cells was determined in the presence of 5.5 or 27.5 mM glucose. The labeling index in 5.5 mM glucose was 0.2 % on the first culture day and this level was the same as that determined in the in vivo experiment. The labeling indices increased and reached a peak of 2-3 % on day 3-5, declined to 1-2 % on day 7 and further to 0.2-0.4 % on day 14. The labeling indices in 27.5 mM glucose attained to the higher levels of 3-4 % on day 3-7, and decreased slowly thereafter. The inability of beta cells to maintain their proliferating capacity under sustained stimulation of high glucose might be one of the causes to induce diabetes in adult age.
