Vascular smooth muscle intracellular calcium-mobilization machinery

The vascular smooth muscle intracellular calcium-mobilization machinery is a coordinated system of proteins and organelles that regulates the concentration of cytosolic calcium ions ([Ca2+]i) in vascular smooth muscle cells (VSMCs) (Hill-Eubanks et al., 2011; Berridge, 2008). This machinery is central to the process of excitation-contraction coupling, where an increase in [Ca2+]i triggers muscle contraction and subsequent vasoconstriction (Sanders, 2001; StatPearls, 2023). The primary components include the sarcoplasmic reticulum (SR), which serves as the main intracellular calcium store, and the release channels located on its membrane: the inositol 1,4,5-trisphosphate receptors (IP3R) and ryanodine receptors (RyR) (UniProt ITPR1, RYR2). Calcium release is typically initiated by G protein-coupled receptor (GPCR) activation, which stimulates phospholipase C to produce IP3, or by calcium-induced calcium release (CICR) via RyRs (Hill-Eubanks et al., 2011). To facilitate relaxation, the sarcoplasmic/endoplasmic reticulum calcium ATPase (SERCA) pumps calcium back into the SR (UniProt ATP2A2). Dysregulation of this machinery, such as excessive calcium release or reduced sequestration, contributes to the pathogenesis of hypertension, vasospasm, and other cardiovascular disorders (Berridge, 2008). Pharmacological modulation of these pathways, including the use of SERCA inhibitors like thapsigargin or IP3R antagonists, provides a means to study and potentially treat vascular diseases by altering vascular tone and resistance.

Other names

VSMC calcium handling machinerySarcoplasmic reticulum calcium release systemIntracellular calcium signaling apparatusVascular smooth muscle calcium signaling pathway

Drugs targeting this machinery act by inhibiting the release of calcium from the sarcoplasmic reticulum via IP3R or RyR, blocking the reuptake of calcium by SERCA, or modulating upstream signaling pathways like the NO-cGMP-PKG axis to reduce cytosolic calcium levels and promote vasodilation.