Family 3: Ion Channel and Membrane Transport
Family overview. Ion channels and membrane transporters regulate electrochemical gradients fundamental to virtually every physiological process: neuronal firing, muscle contraction, immune cell activation, secretory function, and intracellular calcium signalling. Their disruption β by mutation, autoantibody, or post-translational modification β constitutes channelopathy.
Concrete mechanisms and ME/CFS evidence:
TRPM3 channelopathy. Transient receptor potential melastatin 3 (TRPM3) expression and calcium flux are significantly reduced in NK cells of ME/CFS patients versus healthy controls; replicated in large-scale study (2025) (Sasso et al. 2026). TRPM3 dysfunction impairs NK cell activation, calcium-dependent killing, and viral clearance.
TRPM2 and TRPC4 co-dysfunction. Other TRP family members are also dysregulated in ME/CFS NK cells, suggesting a broader TRP channelopathy rather than isolated TRPM3 defect; the full channel expression profile remains to be mapped.
Voltage-gated calcium channel (VGCC) dysregulation. Thalamic T-type (Cav3) and HCN/I_h channels govern thalamocortical oscillatory dynamics; their dysregulation produces the alpha-wave intrusion pattern in slow-wave sleep (see Family 10). Gabapentinoids reduce Cav3 activity and clinically suppress this oscillatory pattern in related conditions.
NaβΊ/KβΊ-ATPase dysfunction. Ion pump failure contributes to cellular energy burden and membrane potential instability; documented indirectly via elevated intracellular sodium in skeletal muscle MRI (Scheibenbogen and Wirth 2025). Direct ATPase activity measurements are lacking.
Red blood cell membrane stiffness. RBCs from ME/CFS patients show ~14% reduced elongation index, ~30% lower membrane fluidity, ~18% reduced net negative surface charge, and elevated RBC ROS; stiffened RBCs cannot transit narrow capillaries, impairing microvascular perfusion (Marshall-Gradisnik et al. 2018).
Aquaporin-4 and glymphatic function. AQP4 water channels on astrocyte perivascular endfeet drive glymphatic CSF clearance during slow-wave sleep; oscillatory disruption reduces the driving force. AQP4 expression and function have not been directly studied in ME/CFS.
Full discussion: Chapter Speculative Mechanistic Hypotheses.
Evidence status: Established for TRP channels (large-scale 2025 confirmation); preliminary/theoretical for other channels.
Is TRPM3/TRP channel dysfunction an isolated finding or part of a broader channelopathy affecting voltage-gated, ligand-gated, and transporter families across multiple cell types? Systematic patch-clamp and expression profiling in T cells, neurons, and endothelial cells would characterise the full scope.