Oxygen consumption oscillates in single clonal pancreatic beta-cells (HIT)

Area of Science:

• Endocrinology
• Cellular Metabolism
• Biophysics

Background:

• Population studies suggest metabolic changes in pancreatic beta-cells precede calcium (Ca2+) level alterations.
• Glucose stimulation induces variable oscillatory patterns in single-cell Ca2+.
• The relationship between glucose, insulin secretion, and oxygen (O2) consumption in beta-cells requires further elucidation.

Purpose of the Study:

• To evaluate the relationship between glucose concentration, insulin secretion, and O2 consumption in the HIT-T-15 beta-cell line.
• To determine the Ca2+ dependency of glucose-induced changes in O2 consumption.
• To investigate the oscillatory nature of O2 consumption in single beta-cells.

Main Methods:

• Utilized a clonal beta-cell line (HIT-T-15) for experiments.
• Employed a self-referencing O2 electrode to measure O2 consumption in single cells.
• Assessed insulin secretion and O2 consumption in response to varying glucose concentrations and Ca2+ levels.
• Used FCCP and antimycin A to modulate cellular respiration.

Main Results:

• A strong correlation exists between respiration and insulin secretion, with half-maximal effects around 1 mmol/l glucose.
• Glucose stimulates O2 consumption even in the absence of Ca2+, but not insulin secretion.
• Single beta-cells exhibit oscillatory O2 consumption in response to glucose, independent of Ca2+.
• The amplitude of O2 oscillations increases with the presence of extracellular Ca2+.

Conclusions:

• Oscillatory O2 consumption in beta-cells is not Ca2+-dependent, but Ca2+ enhances its amplitude, likely supporting insulin secretion and Ca2+ pumping.
• Demonstrated a direct correlation between O2 consumption and insulin secretion.
• Confirmed the oscillatory nature of O2 consumption in single beta-cells.
• Validated the use of a self-referencing O2 electrode for monitoring single beta-cell respiration.