Glucose-sensitivity of the afterhyperpolarization potential: Role of SK1 channel in insulin-secreting cells

The role of the small-conductance, calcium-activated SK potassium channel in regulating pancreatic β cell function remains controversial with conflicting pharmacological results. In this study, we used current clamp recordings to further characterize the function of SK channels in INS-1 cell line. We compared afterhyperpolarization potential (AHP) responses of SK1-downregulated cells with those of control INS-1 cells. They were tested with and without the presence of glucose. We found that cells in which SK1 channel subunit expression had been downregulated exhibited AHPs in the presence of 20 mM glucose while control INS-1 cells had AHPs only in the absence of glucose. Our findings show that the glucose-dependence of the AHP in the rat INS-1 cell line depends only on SK1 channel subunit expression.

► Electrical properties of SK1-knockdown cells were compared with those of INS-1 cells. ► AHPs and resting membrane potentials were measured. ► SK1-knockdown cells had AHPs in glucose and INS-1 cells had AHPs only without glucose. ► AHP responses were associated with more negative resting membrane potentials. ► Glucose-dependence of the AHP in INS-1 cells depend on SK1 channel subunit expression.