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

Intracellular Ca 2+ imaging of GSCa. GSCa responses are one of the most commonly used indexes of β cell f unction. T hey ca n provide real-time results of β cell function. As shown in Fig. 4 , GSCa signaling in INS-1 cells consists of three phases: Phase 0, the initial dip below baseline due to calcium uptake by the endoplasmic reticulum; phase 1, the rapid rise to peak calcium level concomitant with the release of pre-docked insulin granules; and phase 2, the elevated plateau. Addition of 250 µmol/l H 2 O 2 for 15 min to INS-1 cells decreased the fluorescence intensity compared with the control group. Pre-treatment with a 10 -8 mol/l Ang (1-7) for 2 h prior to adding H 2 O 2 upregulated calcium fluorescence by 25%, and A779 can selectively inhibited this effect. Furthermore, pre-incubation with Ang (1-7) restored the amplitude of calcium in phase 1 and A779 blocked this effect (Fig. 4) .