  Despite a vast clinical application of anesthetics, the molecular level of
understanding of general anesthesia is far from our reach. Using atomistic
molecular dynamics simulation, we study the effects of common anesthetics:
ethanol, chloroform and methanol in the fully hydrated symmetric multicomponent
lipid bilayer membrane comprising of an unsaturated
palmitoyl-oleoyl-phosphatidyl-choline (POPC), a saturated
palmitoyl-sphingomyelin (PSM) and cholesterol (Chol) which exhibits phase
coexistence of liquid-ordered (lo) - liquid disordered (ld) phase domains. We
find that the mechanical and physical properties such as the thickness and
rigidity of the membrane are reduced while the lateral expansion of the
membrane is exhibited in presence of anesthetic molecules. Our simulation shows
both lateral and transverse heterogeneity of the anesthetics in the composite
multicomponent lipid membrane. Both ethanol and chloroform partition in the
POPC-rich ld phase domain, while methanol is distributed in both lo-ld phase
domains. Chloroform can penetrate deep into the membrane, while methanol
partitions mostly at the water layer closed to the head-group and ethanol at
the neck of the lipids in the membrane.
