Spreading of @entity1 neutrophils is immediately preceded by a large increase in cytoplasmic free XXXX .

@entity1 @entity1855 @entity593 @entity460 @entity141 @entity2827 @entity855
When @entity1 polymorphonuclear leukocytes (PMN) are placed on various surfaces, they attach and spread rapidly, increasing their diameter severalfold. The spreading is associated with extensive changes in the cytoskeleton. Since many cytoskeletal events are regulated by @entity141 , we measured the cytosolic free @entity460 concentration ([ @entity141 ]i) in individual @entity1 PMN as they spread. [ @entity141 ]i was measured in single cells by microspectrofluorometry using the fluorescent @entity141 -sensitive dye @entity593 . Immediately before spreading, PMN exhibit a rapid increase in [ @entity141 ]i, from 69 +/- 51 nM to 547 +/- 190 nM (mean +/- SD, n = 12). [ @entity141 ]i returns to near resting levels during the next minute, as the cells spread. Neither the spreading nor the [ @entity141 ]i spike is blocked by removal of extracellular @entity460 , by @entity1855 , by calmodulin antagonists, or by mitochondrial or microtubule poisons. Spreading, but not the [ @entity141 ]i increase, is blocked by the microfilament inhibitor cytochalasin B. Both spreading and the [ @entity141 ]i spike are blocked by @entity855 depletion and reversibly blocked by placing the cells in medium containing hypertonic sucrose or @entity2827 . These data strongly suggest that an increase in [ @entity141 ]i, derived from nonmitochondrial intracellular pools, plays an important role in the microfilament-mediated process of PMN spreading.
