The separate roles of calcium and mechanical forces in mediating cell death in mechanically injured neurons.

In this study, we examine the response of cultured hippocampal neurons to mechanical stretch. To measure the immediate response, we measured the response of a calcium sensitive fluorescent dye (Fura-2AM) prior to and for five minutes following stretch. In separate experiments, we measured the viability of the cells using propidium iodide labeling at 24 hours following a single stretch. Results show that cytosolic calcium increases immediately following stretch to levels much higher than those associated with maximal chemical agonist (NMDA) stimulation. Moreover, the calcium response data indicate a loss in calcium regulation in the neurons at the most severe level of stretch. Finally, at the highest levels of stretch, the cell survivability decreases at 24 hrs following the stretch injury. These data show the association between loss in calcium regulation and early signs of neuronal cell death.