Hydrodynamic model of temperature change in open ionic channels

Area of Science:

• Biophysics
• Computational Biology
• Physical Chemistry

Background:

• Existing Poisson-Nernst-Planck theories for ionic channels neglect heat generation from current flow.
• Heat effects are significant in analogous semiconductor systems, suggesting their importance in biological channels.
• A generalized theory is needed to incorporate thermal effects in ionic channel function.

Purpose of the Study:

• To develop and apply a hydrodynamic model for ionic channels that includes heat generation and transport.
• To investigate the impact of temperature changes on ionic flux and channel dynamics.
• To determine the conditions under which the hydrodynamic model is necessary over simpler theories.

Main Methods:

• Combined Poisson and Euler field equations from electrostatics and fluid dynamics.
• Incorporated conservation laws for mass, heat, and charge (current) flow.
• Utilized a stable and accurate nonoscillatory shock-capturing numerical scheme for integration.

Main Results:

• Significant exchange of electrical energy with permeating ions was observed.
• Local ion temperatures increased by tens of degrees, notably affecting ionic flux in channels like gramicidin-A.
• A saturation velocity parameter was identified, distinguishing between overdamped, intermediate, and unrestricted ionic motion regimes.

Conclusions:

• Heat generation is a significant factor in open ionic channel function.
• The hydrodynamic model provides a more accurate description of ionic transport when thermal effects are considered.
• Temperature changes critically influence ion flux and necessitate advanced modeling approaches.