Sydnone SYD-1 affects the metabolic functions of isolated rat hepatocytes

Previously, we demonstrated that sydnone SYD-1 (3-14-chloro-3-nitrophenyl]-1,2,3-oxadiazolium-5-olate) impairs the mitochondrial functions linked to energy provision and suggested that this effect could be associated with its antitumor activity. Herein, we evaluated the effects of SYD-1 (25 and 50 mu M) on rat hepatocytes to determine its cytotoxicity on non-tumor cells. SYD-1 (25 and 50 mu M) did not affect the viability of hepatocytes in suspension after 1-40 min of incubation. However, the viability of the cultured hepatocytes was decreased by similar to 66% as a consequence of treatment with SYD-1 (50 p,M) for 18 h. Under the same conditions, SYD-1 promoted an increase in the release of LDH by similar to 19%. The morphological changes in the cultured cells treated with SYD-1 (50 mu M) were suggestive of cell distress, which was demonstrated by the presence of rounded hepatocytes, cell fragments and monolayer impairment. Furthermore, fluorescence microscopy showed an increase in the annexin label after treatment with SYD-1 (50 JAM), suggesting that apoptosis had been induced in these cells. SYD-1 did not affect the states of respiration in the suspended hepatocytes, but the pyruvate levels were decreased by 36%, whereas the lactate levels were increased by similar to 22% (for the 50 mu M treatment). The basal and uncoupled states of respiration of the cultured hepatocytes were inhibited by similar to 79% and similar to 51%, respectively, by SYD-1 (50 mu M). In these cells, SYD-1 (50 p,M) increased the pyruvate and lactate levels by,similar to 84% and similar to 16%, respectively. These results show that SYD-1 affects important metabolic functions related to energy provision in hepatocytes and that this effect was more pronounced on cells in culture than those in suspension. (C) 2014 Elsevier Ireland Ltd. All rights reserved.