P72 The bidirectional effect of hydrogen sulfide on Ca2+ signals via opening KATP and TRPA1 channels in RIN14B cells

Abstract

Hydrogen sulfide (H2S) is reported to cause various cellular activities, such as relaxation in smooth muscles and excitation in neurons, through several ion channels including ATP-sensitive K+ (KATP) channels and transient receptor potential (TRP) A1 channels. We investigated the effect of NaHS, an H2S donor, on RIN14B cells, a rat pancreatic delta cell line, in which both KATP and TRPA1 channels were expressed. The intracellular Ca2+ concentration ([Ca2+]i) and 5HT release were measured using Ca2+ imaging system with fura-2 and high performance liquid chromatography with electrochemical detector. The application of NaHS for 10 min caused several patterns of [Ca2+]i changes. In 37% of the cells tested, NaHS inhibited the spontaneous Ca2+ oscillation. In 24% of the cells, NaHS slowly increased [Ca2+]i after brief inhibition of Ca2+ oscillation. In the presence of KATP channel blockers, glibenclamide or tolbutamide, any inhibitory effects of NaHS were not observed, and thus [Ca2+]i increases by NaHS were enhanced. NaHS-induced [Ca2+]i increases were inhibited by extracellular Ca2+ removal, HC030031 (TRPA1 antagonist), and dithiothreitol (DTT; reducing agent). NaHS increased 5-HT release from RIN14B cells, which was also inhibited by HC030031 and DTT. These results indicates that H2S has both inhibitory and excitatory effects via opening KATP and TRPA1 channels, respectively, suggesting the possibility of bidirectional modulation by H2S in secretory cells.