Critical transitions in pancreatic islets.

Area of Science:

• Endocrinology
• Systems Biology
• Biophysics

Background:

• Pancreatic beta cells regulate glucose homeostasis through collective calcium signaling.
• The transition to coordinated signaling under rising glucose concentrations resembles a phase transition, but its order is unclear.

Purpose of the Study:

• To investigate the order and nature of the phase transition in pancreatic beta cell collective calcium signaling.
• To understand the role of islets as critical tipping elements in glucose-induced insulin release.

Main Methods:

• Confocal microscopy was used to record collective calcium activity in intact pancreatic islets.
• Glucose concentration was systematically varied (increasing then decreasing) to observe signaling dynamics.
• A computational network model incorporating link selection and coordination was developed.

Main Results:

• A sharp transition from uncorrelated to correlated calcium signaling was observed as glucose increased.
• Hysteresis in the coordinated calcium response was identified, indicating a first-order phase transition.
• The network model successfully replicated the observed hysteresis and critical transition dynamics.

Conclusions:

• The collective calcium response of pancreatic beta cells exhibits a critical, first-order phase transition with hysteresis.
• Islets function as interconnected tipping elements, driving abrupt insulin release through critical dynamics.