Glucose inhibits insulin release induced by Na+ mobilization of intracellular calcium

Abstract

⁴⁵Ca²⁺ incorporated in response to glucose was selectively mobilized from the β-cell-rich pancreatic islets of ob/ob-mice after raising the intracellular Na⁺ by removal of K⁺ or addition of ouabain or veratridine. Also studies of insulin release indicated opposite effects of glucose and Na⁺ on the intracellular sequestration of calcium. The fact that glucose inhibits insulin release induced by raised intracellular Na⁺ indicates that this sugar can lower the cytoplasmic [Ca²⁺]. The concept of a dual action of glucose on the cytoplasmic [Ca²⁺]. The concept of a dual action of glucose on the cytoplasmic [Ca²⁺] might well explain previous observations of an inhibitory component in the glucose action on the ⁴⁵Ca²⁺ efflux.