N-acetyl-L-cysteine and cysteine increase intracellular calcium concentration in human neutrophils

Hasan, Md Ashraful; Ahn, Won Gyun; Song, Dong Keun

Abstract

N-acetyl-L-cysteine (NAC) and cysteine have been implicated in a number of human neutrophils' functional responses. However, though Ca²âº signaling is one of the key signalings contributing to the functional responses of human neutrophils, effects of NAC and cysteine on intracellular calcium concentration ([Ca²âº]áµ¢) in human neutrophils have not been investigated yet. Thus, this study was carried out with an objective to investigate the effects of NAC and cysteine on [Ca²âº]áµ¢ in human neutrophils. We observed that NAC (1 µM ~ 1 mM) and cysteine (10 µM ~ 1 mM) increased [Ca²âº]áµ¢ in human neutrophils in a concentration-dependent manner. In NAC pre-supplmented buffer, an additive effect on N-formyl-methionine-leucine-phenylalanine (fMLP)-induced increase in [Ca²âº]áµ¢ in human neutrophils was observed. In Ca²âº-free buffer, NAC- and cysteine-induced [Ca²âº]áµ¢ increase in human neutrophils completely disappeared, suggesting that NAC- and cysteine-mediated increase in [Ca²âº]áµ¢ in human neutrophils occur through Ca²âº influx. NAC- and cysteine-induced [Ca²âº]áµ¢ increase was effectively inhibited by calcium channel inhibitors SKF96365 (10 µM) and ruthenium red (20 µM). In Naâº-free HEPES, both NAC and cysteine induced a marked increase in [Ca²âº]áµ¢ in human neutrophils, arguing against the possibility that Naâº-dependent intracellular uptake of NAC and cysteine is necessary for their [Ca²âº]áµ¢ increasing activity. Our results show that NAC and cysteine induce [Ca²âº]áµ¢ increase through Ca²âº influx in human neutrophils via SKF96365- and ruthenium red-dependent way.