Oscillations, intercellular coupling, and insulin secretion in pancreatic beta cells

Abstract

Insulin is a potent metabolic regulator that is released by pancreatic beta-cells, which respond to body glucose concentrations. Here the authors explain the physiological basis of insulin release.

Figure 1. Pancreatic Endocrine Tissue Comprises 1%, or Less, of the Pancreas and Is Organized as Clusters of Cells Dispersed throughout the Exocrine Pancreas

These cell clusters, the islets of Langerhans, are heterogeneous and composed of three main cell types that secrete distinct hormones. The majority of islet cells comprise insulin secreting β cells and act as glucose sensors, releasing insulin in response to increased circulating glucose. The mechanism controlling regulated insulin secretion from β cells is shown in the right panel.

Figure 2. The Responses of β Cells within Intact Islets Are Oscillatory and Synchronised

Here, the intracellular Ca ²⁺ responses were measured using ratiometric methods and confocal microscopy. In islet β cells, marked R1-R6 in (A), glucose-stimulation results in increases in intracellular Ca ²⁺ as shown in (B). Oscillations in intracellular Ca ²⁺, with a period of ∼10 s, are observed. Furthermore, as seen in the expanded time scale in (C), these oscillations are synchronized within separate β cells throughout the islet.