Salicylate induced changes in outer hair cell lateral wall stiffness.

Micropipette aspiration was used to study the lateral wall stiffness of isolated guinea pig outer hair cells (OHCs) perfused with a sodium salicylate solution. Salicylate treatment significantly decreased lateral wall stiffness as measured by a stiffness parameter (S) compared to cells perfused with a standard bathing solution (S = 0.68 +/- 0.26 vs. S= 1.09 +/- 0.25, P < 0.05). The effect was reversible cells treated with salicylate and then with bathing solution exhibited a lateral wall stiffness similar to control cells (S = 1.10 +/- 0.40. P=0.94). Salicylate perfusion diminishes electromotile responses in isolated OHCs and physiologic doses of salicylate produce hearing loss and tinnitus in human subjects. The OHC lateral wall, the locus of electromotility, consists of three concentric layers: (1) an outermost plasma membrane, (2) a cytoskeletal network of actin and spectrin called the cortical lattice and (3) an innermost collection of flattened membranes called the subsurface cisternae (SSC). Ultrastructural studies have shown that salicylate treatment dilates and vesiculates the lateral wall subsurface cisternae (SSC) in guinea pig OHCs. In addition, salicylate causes an outward curvature of plasma membranes in human erythrocytes. The reversible, salicylate induced increase in lateral wall compliance may result from a direct action on the SSC and/or the plasma membrane.