Antioxidant pyrrolidine dithiocarbamate prevents defective bradykinin-stimulated calcium accumulation and nitric oxide activity following exposure of endothelial cells to elevated glucose concentration

Abstract

Endothelium-dependent relaxation is impaired in diabetes [1±4]. It is probable that chronic exposure of blood vessels to elevated glucose concentrations contribute to impaired endothelium-dependent relaxation in diabetes mellitus since restoration of glycaemic control by islet [5] or whole pancreas [6] transplantation restores relaxation to normal. This hypothesis is strengthened by studies showing that exposure of normal arteries to elevated glucose concen-Release of agonist-stimulated NO from the vascular endothelium which contributes to endotheliumdependent relaxation is regulated by increases in intracellular calcium concentration [Ca While defective endothelium-dependent relaxation after exposure of intact blood vessels to elevated glucose concentration is believed to be mediated via oxygen-derived free radicals, the role of oxygenderived free radicals contributing to impaired Ca 2+ i signalling and NO production in isolated endothelial cells exposed to elevated glucose concentration has yet to be ascertained. In the present study, we evaluated the efficacy of PDTC, an antioxidant and metal chelator [14,15], in preventing glucose-induced defects in Ca 2+ i signalling in bovine aortic endothelial Diabetologia (1998) Summary Previous studies from our laboratory suggest that reactive oxygen contributes to diminished bradykinin-stimulated calcium accumulation in endothelial cells exposed to elevated glucose concentrations. In this study, we evaluated the efficacy of the antioxidant pyrrolidine dithiocarbamate (PDTC), in preventing defects in intracellular calcium signalling and nitric oxide (NO) activity in endothelial cells exposed to elevated glucose concentration. We show that PDTC prevented the elevated glucose-induced impairment in bradykinin-stimulated calcium accumulation without changing the normal calcium accumulation in response to ionomycin. Furthermore, the impaired cyclic GMP in RFL-6 detector cells (an index of NO activity) generated by bradykinin-stimulation of high glucose-exposed endothelial cells was restored to normal by pretreatment with PDTC. These studies support a role of reactive oxygen in elevated glucose-induced defects in calcium signalling and NO activity by endothelial cells and that antioxidants may be useful in preventing this defect. [Diabetologia (1998) 41: 806±812]

High glucose enhances store-operated calcium entry by upregulating ORAI/STIM via calcineurin-NFAT signalling

“…Previous studies have shown that HG affects intracellular Ca 2+ level or Ca 2+ homeostasis [27][28][29]. The different responses between acute application and chronic treatment has been demonstrated, i.e., acute application of HG had less effect on Ca 2+ influx, but chronic treatment by incubation with HG for 2-4 days significantly increased the Ca 2+ influx in HUVECs [19], porcine aortic endothelial cells [30] and in EA.hy926 cells as shown in this study and others [31]; however, an opposite effect was reported in mouse coronary endothelial cells [20].…”

Inhibition of Store-Operated Calcium Entry Protects Endothelial Progenitor Cells from H2O2-Induced Apoptosis

“…Accumulating evidence suggests that oxidative stress-induced injuries might be attenuated by stabilizing intracellular calcium homeostasis ( Godfraind, 2005 ; Ohyama et al ., 2012 ). Moreover, some studies have indicated that antioxidants diminish increases in intracellular calcium levels ( Pieper and Dondlinger, 1998 ; Su et al ., 1999 ). Although the specific mechanism of the reduction of intracellular calcium following antioxidant application is still not clear, we hypothesized that the decrease in intracellular ROS production in response to antioxidant insult might lead to a change in the intracellular calcium level.…”