Antibody to the inositol trisphosphate receptor blocks thimerosalenhanced Ca2+‐induced Ca2+ release and Ca2+ oscillations in hamster eggs

Abstract

The sulfhydryl reagent thimerosal enhanced the sensitivity of hamster eggs to injected inositol 1,4,5‐trisphosphate (InsP₃) or Ca²⁺ to generate regenerative Ca²⁺ release from intracellular pools. A monoclonal antibody (mAb) to the InsP₃ receptor blocked both the InsP₃‐induced Ca²⁺ release (IICR) and Ca²⁺‐induced Ca²⁺ release (CICR). The mAb also blocked Ca²⁺ oscillations induced by thimerosal. The results indicate that thimerosal enhances IICR sensitized by cytosolic Ca²⁺, but not CICR from InsP₃‐insensitive pools, and causes repetitive Ca²⁺ releases from InsP₃‐sensitive pools.