Details

Autor(en) / Beteiligte

• Yang, Wei
• Yang, Guangdong
• Jia, Xuming
• Wu, Lingyun
• Wang, Rui

Titel

Activation of K sub(ATP) channels by H sub(2)S in rat insulin-secreting cells and the underlying mechanisms

Ist Teil von

• The Journal of physiology, 2005-12, Vol.569 (2), p.519-531

Erscheinungsjahr

2005

Quelle

Wiley Online Library Journals Frontfile Complete

Beschreibungen/Notizen

• H sub(2)S is an important gasotransmitter, generated in mammalian cells from L-cysteine metabolism. As it stimulates K sub(ATP) channels in vascular smooth muscle cells, H sub(2)S may also function as an endogenous opener of K sub(ATP) channels in INS-1E cells, an insulin-secreting cell line. In the present study, K sub(ATP) channel currents in INS-1E cells were recorded using the whole-cell and single-channel recording configurations of the patch-clamp technique. K sub(ATP) channels in INS-1E cells have a single-channel conductance of 78 pS. These channels were activated by diazoxide and inhibited by gliclazide. ATP (3 mM) in the pipette solution inhibited K sub(ATP) channels in INS-1E cells. Significant amount of H sub(2)S was produced from INS-1E cells in which the expression of cystathinonie gamma-lyase (CSE) was confirmed. After INS-1E cells were transfected with CSE-targeted short interfering RNA (CSE-siRNA) or treated with DL-propargylglycine (PPG; 1-5 mM) to inhibit CSE, endogenous production of H sub(2)S was abolished. Increase in extracellular glucose concentration significantly decreased endogenous production of H sub(2)S in INS-1E cells, and increased insulin secretion. After transfection of INS-1E cells with adenovirus containing the CSE gene (Ad-CSE) to overexpress CSE, high glucose-stimulated insulin secretion was virtually abolished. Basal K sub(ATP) channel currents were significantly reduced after incubating INS-1E cells with a high glucose concentration (16 mM) or lowering endogenous H sub(2)S level by CSE-siRNA transfection. Under these conditions, exogenously applied H sub(2)S significantly increased whole-cell K sub(ATP) channel currents at concentrations equal to or lower than 100 mu M. H sub(2)S (100 mu M) markedly increased open probability by more than 2-fold of single K sub(ATP) channels (inside-out recording) in native INS-1E cells (n= 4, P < 0.05). Single-channel conductance and ATP sensitivity of K sub(ATP) channels were not changed by H sub(2)S. In conclusion, endogenous H sub(2)S production from INS-1E cells varies with in vivo conditions, which significantly affects insulin secretion from INS-1E cells. H sub(2)S stimulates K sub(ATP) channels in INS-1E cells, independent of activation of cytosolic second messengers, which may underlie H sub(2)S-inhibited insulin secretion from these cells. Interaction among H sub(2)S, glucose and the K sub(ATP) channel may constitute an important and novel mechanism for the fine control of insulin secretion from pancreatic beta -cells.