How is the potassium ion gradient maintained in beta cells?

The beta cells in the islets of langerhans maintain a potential difference gradient by potassium ions diffusing out of the cell. Where does the potassium in the cell come from and how is this diffusion gradient maintained?


Thank YouHow is the potassium ion gradient maintained in beta cells?
Insulin is the first-line defense against hyperkalemia. A rise in plasma K+ stimulates insulin release by the pancreatic beta cell. Insulin, in turn, enhances cellular potassium uptake, returning plasma K+ towards normal. The enhanced cellular uptake of K+ that results from increased insulin levels is thought to be largely due to the ability of insulin to stimulate activity of the sodium potassium ATPase located in cell plasma membranes. The insulin induced cellular uptake of potassium is not dependent on the uptake of glucose caused by insulin. Insulin deficiency allows a mild rise in plasma K+ chronically and makes the subject liabel to severe hyperkalemia if a potassium load is given. Conversely, potassium deficiency may cause decreased insulin release. Thus plasma potassium and insulin participate in a feedback control mechanism.