Antioxidant effect of angiotensin (1-7) in the protection of pancreatic ß cell function

Zhang, Fen; Liu, Chang; Wang, Lei; Cao, Xi; Wang, Ying Ying; Yang, Jin Kui

In pancreatic β cells, the regulation of intracellular calcium is crucial to the processes of insulin secretion (26) ; thus, analyzing GSCa responses can provide information regarding the viability and function of pancreatic β cells. GSCa results can be obtained rapidly and at a lower cost than GSIS (27) . In addition, the calcium curve directly reflects the changes in insulin secretion within the first 15 min following the addition of glucose. In the present study, it was observed that the intracellular calcium fluorescence intensity and the amplitude of insulin secretion in the first phase significantly decreased following treatment with H 2 O 2 . This result is consistent with the insulin secretion experiment, which suggests that the reduction of insulin secretion is correlated with a decrease in intracellular calcium. Ang (1-7) can restore the calcium A B fluorescent intensity and the signaling peak of first phase insulin secretion. Moreover, A779 can block this effect. This study confirmed that oxidative stress can cause a decline in intracellular calcium, which results in the reduction of first phase insulin secretion in pancreatic cells, and Ang-(1-7) can restore this early β cell dysfunction associated with calcium levels. Our previous study showed that ACE2 knockout mice exhibited progressive impairments in glucose tolerance and reduced first-phase insulin secretion (14) ; thus, in vivo and in vitro experiments were consistent. These results demonstrated the importance of the ACE2-Ang (1-7)-Mas axis in the early stages of diabetes and its protective role in the early treatment of diabetes, as well as the correlation with Ang (1-7) and oxidative stress in INS-1 cells.