NO SYNTHASE ACTIVITY DOES NOT INFLUENCE ELECTRICAL-ACTIVITY OF MOUSE PANCREATIC B-CELLS

The membrane potential of mouse pancreatic B-cells was recorded with i ntracellular microelectrodes. At a low concentration the NO synthase i nhibitor N-omega-nitro-L-arginine methylester (L-NAME, 100 mu mol/l) d id not alter electrical activity induced by 15 mmol/l glucose. At 5 mm ol/l L-NAME depolarized B-cells similarly to L-arginine. The depolariz ation of the B-cell membrane induced by 5 mmol/l L-arginine in the pre sence of 15 mmol/l glucose was not inhibited but further increased by the addition of 15 mmol/l L-NAME. D-arginine which is not used as a su bstrate by the NO synthase also depolarized the B-cells. However, high er concentrations were necessary than for L-arginine pointing to a pre ferential transport of the L-enantiomer. It is concluded that the elec trical activity of pancreatic B-cells is not influenced by the NO synt hase and that the enzyme is not involved in the arginine-induced depol arization of B-cells. (C) 1995 Academic Press, Inc.