Stimulation of insulin release by thiols.
The effects of thiol compounds on insulin release were studied in microdissected pancreatic islets of non-inbred ob/ob micemin control experiments the reactivity of thiols against 6,6'-dithiodinicotinic acid and the degradation of mouse insulin were measured. At a concentration of 0.1 mM, 1-thio-D-glucose or reduced glutathione potentiated the insulin-releasing action of 10 mM D-glucose without affecting glucose oxidation. When tested at a concentration equivalent to about 0.1 mM reactive thiol, dextran-linked L-cysteine also potentiated the glucose-induced insulin secretion. In microperifusion experiments the insulin-releasing action of 1-thio-D-glucose was found to exhibit a rapid onset followed by a decline of the secretory rate to values lower than those observed with 10 mMD-glucose alone. No thiol stimulated insulin release in the absence of glucose. It is suggested that thiol compounds stimulate insulin release by splitting membrane disulphides in the beta-cells.