Determine the astrocytic IP3 receptor cluster size

Determine the precise number of inositol trisphosphate (IP3) receptors per cluster in astrocytes (denoted N_IP3) used in the stochastic Li–Rinzel-based G-ChI astrocyte model, in order to replace the assumption N_IP3 = 20 and enable more accurate modeling of astrocytic calcium oscillations and gliotransmitter release within the neuro-glial-vascular unit framework.

Background

In the astrocyte module, the authors employ a stochastic Li–Rinzel formulation to capture IP3-mediated calcium dynamics, which depends on clustered IP3 receptors. The model assumes a fixed cluster size, N_IP3, due to the lack of precise empirical knowledge.

Because the opening probability of clustered IP3 receptors modulates calcium release and downstream gliotransmission, uncertainty in N_IP3 directly affects predictions of astrocytic signaling and its vascular impact. Establishing N_IP3 empirically would reduce model uncertainty and improve the fidelity of simulated neuro-glial-vascular coupling.

References

The cluster size, $N_{IP3}$, is not precisely known and is assumed to be 20 in this context (cf.~\citep{shuai2002stochastic}).

— A 3D-1D-0D Multiscale Model of the Neuro-Glial-Vascular Unit for Synaptic and Vascular Dynamics in the Dorsal Vagal Complex (2504.02540 - Hermann et al., 3 Apr 2025) in Subsubsection “Astrocyte Calcium Dynamics and Gliotransmitter Release,” Section 3 (Neuro-Glial-Vascular Unit Model)