Phospholipid bilayer of dystrophic muscle cell membranes

The phospholipid bilayer of dystrophic muscle cell membranes, known as the sarcolemma, forms a 5-6 nm thick asymmetrical lipid structure primarily composed of phospholipids, sphingolipids, glycolipids, and sterols, with embedded proteins for ion conduction, signaling, and structural support. In healthy muscle, it maintains intracellular homeostasis by acting as a selective barrier, exhibiting properties like fluidity, rigidity, elasticity, and tensile strength essential for withstanding contraction forces. In dystrophic conditions such as Duchenne muscular dystrophy (DMD), the absence of dystrophin—a key cytoskeletal protein in the dystrophin-glycoprotein complex—destabilizes this bilayer, leading to fragility, delta lesions, and contraction-induced tears, particularly during lengthening contractions. This results in pathological calcium influx, activation of calpains and proteases, reactive oxygen species production, mitochondrial dysfunction, and muscle fiber necrosis, with clinical hallmarks like persistent creatine kinase leakage. Therapeutic strategies target this bilayer directly using amphiphilic block copolymers like Poloxamer 188 (P188), which insert into damaged areas via their hydrophobic poly(propylene oxide) blocks to seal defects, block calcium entry, and preserve membrane integrity, showing promise in mdx mouse models for improving muscle function.

Other names

sarcolemma of dystrophic muscledystrophic muscle membranedystrophin-deficient muscle membrane

Insertion of hydrophobic block into damaged membrane to seal defects and prevent extracellular calcium influx, Reduces membrane permeability to macromolecules like Evans blue dye, Restores cellular compliance during mechanical stretch