Using Fura-2AM microfluorimetry, the effect of oxidized glutathione (GSSG) and its pharmacological analogue glutoxim on the intracellular Ca2+ concentration in rat peritoneal macrophages was investigated. It was shown that GSSG or glutoxim increase the intracellular Ca2+ concentration by inducing Ca2+ mobilization from thapsigargin-sensitive Ca2+ stores and subsequent Ca2+ entry from external medium. Dithiothreitol, which reduces S-S-bonds in proteins, completely prevents or reverses the increase of intracellular Ca2+ concentration induced by GSSG or glutoxim. This suggests that the increase of intracellular Ca2+ concentration induced by GSSG or glutoxim can be mediated by their interactions with functionally important SH-groups of proteins involved in Ca2+-signaling.
Two structurally different tyrosine kinase inhibitors genistein and methyl-2,5-dihydroxycinnamate prevent or completely reverse the increase in the intracellular Ca2+ concentration induced by GSSG or glutoxim. On the contrary, tyrosine phosphatase inhibitor Na orthovanadate enhances the increase of intracellular Ca2+ concentration evoked by oxidizing agents. The data suggest that tyrosine kinases and tyrosine phosphatases are involved in the regulatory effect of GSSG and glutoxim on the intracellular Ca2+ concentration in macrophages.