University at Buffalo biophysicists have identified a component of venom from a very large, very hairy Chilean tarantula that blocks the action of ion channels that are responsible for cellular mechanical responses -- the cell's ability to feel. These channels or pores in the cell membrane -- called stretch-activated channels because stretching the membrane causes them to open and close -- have been implicated in functions as diverse as the senses of touch and hearing, muscle contraction and coordination, and blood pressure and volume regulation.