The stimulus secretion coupling of glucose-induced insulin release. XXVII. Effect of glucose on K+ fluxes in isolated islets.

The effect of glucose upon the handling of K+ by islets of Langerhans removed from normal rats was investigated by measuring both the net uptake of 86Rb+ and its efflux from prelabelled islets. The inflow of K+ into islet cells is mediated, in part at least, by an ouabain-sensitive pump. Glucose fails to affect the inflow rate of K+, but it apparently decreases the permeability of islet cells plasma membrane to effuent K+. The glucose-induced change in permeability is a rapid and rapidly reversible phenomenon. Under steady-state conditions, it leads to an increase in the islet cells K+ pool and a decrease of its fractional turnover rate.