  Field-theoretical method is proposed, that yields analytical expression for
lateral pressure distribution across hydrophobic core of a bilayer lipid
membrane. Lipid molecule, repelling entropicaly surrounding neighbors, is
modeled as a flexible string embedded between confining walls in the
self-consistent harmonic potential. At room temperature the pressure profile is
expressed solely via lowest energy eigenfunctions of the operator of the string
energy density. Analytical results compare favorably with molecular dynamics
simulations. The theory is suited to study protein-lipid interaction.
