Modeling calcium waves in an anatomically accurate three-dimensional parotid acinar cell

Area of Science:

• Computational biology
• Cellular physiology
• Biophysics

Background:

• Saliva secretion involves complex intracellular calcium (Ca2+) signaling.
• Understanding calcium wave propagation in parotid acinar cells is essential for elucidating secretion mechanisms.

Purpose of the Study:

• To construct and analyze a 3D computational model of calcium waves in an anatomically accurate parotid acinar cell.
• To investigate the role of inositol trisphosphate receptor (IPR) density gradients and spatial separation of IP3 production and action sites on calcium wave formation and characteristics.

Main Methods:

• Development of a 3D computational model based on experimental data of a parotid acinar cell.
• Incorporation of gradients in inositol trisphosphate receptor (IPR) density, with higher density near the lumen.
• Simulation of inositol trisphosphate (IP3) production at the basal membrane and analysis of resulting calcium dynamics.

Main Results:

• Inositol trisphosphate (IP3) equilibrates rapidly, allowing for spatially homogeneous distribution.
• Spatial separation of IP3 production and action sites facilitates stable, oscillatory Ca2+ waves, driven by temporal delays rather than traveling wave profiles.
• Ryanodine receptors modulate but are not essential for Ca2+ wave existence.
• Spatially independent models are insufficient for studying saliva secretion; 1D models may suffice.

Conclusions:

• The 3D model demonstrates that oscillatory Ca2+ waves can form despite spatial separation of IP3 production and action sites.
• Temporal delays, not traveling wave profiles, characterize these Ca2+ waves.
• This study provides foundational insights for multiscale modeling of saliva secretion in salivary glands.