Salicylate induced changes in outer hair cell lateral wall stiffness

Micropipette aspiration was used to study the lateral wall stiffness of iso lated guinea pig outer hair cells (OHCs) perfused with a sodium salicylate solution. Salicylate treatment significantly decreased lateral wall stiffne ss 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 cell s (S= 1.10 +/- 0.40, P=0.94). Salicylate perfusion diminishes electromotile responses in isolated OHCs and physiologic doses of salicylate produce hea ring loss and tinnitus in human subjects. The OHC lateral wall, the locus o f electromotility, consists of three concentric layers: (1) an outermost pl asma membrane, (2) a cytoskeletal network of actin and spectrin called the cortical lattice and (3) an innermost collection of flattened membranes cal led the subsurface cisternae (SSC). Ultrastructural studies have shown that salicylate treatment dilates and vesiculates the lateral wall subsurface c isternae (SSC) in guinea pig OHCs. In addition, salicylate causes an outwar d curvature of plasma membranes in human erythrocytes. The reversible, sali cylate induced increase in lateral wall compliance may result from a direct action on the SSC and/or the plasma membrane. (C) 1999 Elsevier Science B. V. All rights reserved.