<b>STUDY OF PANCREATIC DNA SYNTHESIS <i>IN VIVO</i> AND <i>IN VITRO</i> FOLLOWING CAERULEIN TREATMENT <i>IN </i></b><b><i>VIVO </i></b>

Abstract

Rats were given subcutaneous injections of caerulein, l ,ug-kg'.1, 3 times daily for 2 days. Pancreatic DNA synthesis was studied in vivo and in vitro in order to clarify discrepancies existing in the literature regarding results obtained with the use of these two techniques on evaluation of tritiated thymidine incorporation into DNA. After 2 days of caerulein treatment, [3H]thymidine incorporation was significantly increased over control in vivo by 361 'X, and in virro by 396 'X, using pancreatic segments and by 495 'X, using dispersed acini. Within each experiment, free labeled thymidine pools were not modified at any time. The observation that four different segments of pancreatic tissue incorporated thymidine at the same rate on a DNA basis within the control and the stimulated groups indicate that one segment of rat pancreas can be representative of the entire organ. Moreover, since increases in DNA snythesis were comparable in each of the 4 segments after caerulein, it is believed that promoted growth is triggered similarly in all regions of the pancreas.