Diffusion and Interaction between ion Ca2+ and ion Gd3+ in a Model Synapse: A Monte Carlo Study

Abstract

Gadolinium (Gd³⁺) is a commonly used in MRI. The role of Gd³⁺ as contrast agent greatly helps to improve the quality of an image and Gadolinium entrance in a body through a diffusion process after administration. Diffusion process takes place from outside pre-synapse to inside pre-synapse through Ca²⁺ channels. This process causes a delay of Ca²⁺ in passing Ca²⁺ channels to pre-synapse. This study aims to determine equilibrium concentration of Ca²⁺ and Gd³⁺ so that Ca²⁺ can pass Ca²⁺ channels. To address the effect of Gd³⁺ concentration around Ca²⁺ channels, we developed a Monte Carlo simulation on Ca diffusion and interaction with Gd. We find Gd³⁺ concentration in a certain threshold can be potential as a blocker Ca²⁺ diffuse entrance into pre-synapse. In another hand, an amount of Ca²⁺ channels and pre-synapse terminal to continuing diffusion of vesicles to clef was important. And the trapping Gd³⁺ in pre-synapse effects in diffusion delays also. These simulations identify characteristics of the interaction between Ca²⁺ and Gd³⁺ in Ca channels which entrance into pre-synapse through diffusion process depend on concentration with each other.