All organisms have mechanisms to respond to osmotic shock, with sensors and signal transduction networks providing information to the cell about the osmolarity of its surroundings, these signals activate responses to deal with extreme conditions. Although single-celled organisms are more vulnerable to osmotic shock, since they are directly exposed to their environment, cells in large animals such as mammals still suffer these stresses under some conditions.
Calcium acts as one of the primary regulators of osmotic stress. Intracellular calcium levels rise during hypo-osmotic and hyper-osmotic stresses. During hyper-osmotic stress extracellular albumin binds calcium.
Transient intracellular Ca2+ increase.
Calcium dependent efflux of the osmolyte Taurine. Extracellular calcium removal was found to prevent Taurine efflux by 50%, and removal of extracellular Ca2+ and simultaneous depletion of intracellular Ca2+ stores with thapsigargin decreased it by 85%..