IN-VITRO AND IN-VIVO FUNCTIONS OF RAT PANCREATIC BETA-CELL LINES

RINm5F cells did not respond in vitro to glucose but responded significantly to other insulin secretagogues; Hybrid rat (NEDH) pancreatic beta-cell line, D11 cells, responded in vitro to 5.6 mM glucose but not further to 16.7 mM glucose. The extent of 5.6 mM glucose-response is similar to that of islet cell. However, islet cells responded significantly to 16.7 mM glucose (P<0.05). Generally, transplanted RINm5F cells responded in vitro to 5.6 mM glucose rather than 16.7 mM glucose. RINm5F cells transplanted into mouse seem to release constantly insulin and plasma insulin level change of the mouse disagreed with blood glucose concentration fluctuation. So, RINm5F cells in the mice appear not to control blood glucose level properly (7-15 mM). D11 cells taken from mouse did not respond in vitro to 5.6 mM glucose but responded to 16.7 mM glucose. Plasma insulin level in the mice carrying D11 cells increased very slowly with blood glucose concentration under 9 mM and rapidly over 10 mM. Accordingly, mice carrying D11 cells showed well-controlled blood glucose level (7-11 mM). D11 cells seem to sense blood glucose concentration and secrete insulin properly to maintain normal blood glucose. In vivo conditions and islet cell interaction seem essential factors to keep accurate insulin secretion.