Exudative neutrophils show impaired pH regulation compared with circulating neutrophils
D. J. Hackam, S. Grinstein, A. Nathens, W. G. Watson, J. C. Marshall and O. D. Rotstein
Department of Surgery, Toronto Hospital, University of Toronto, Ontario.
OBJECTIVE: To investigate the effects of neutrophil (PMN) transmigration
into inflammatory sites on cytosolic pH (pHi) regulation. DESIGN: Exudative
PMNs were obtained by bronchoalveolar lavage from rats sustaining
endotoxin-induced lung injury. Circulating PMNs were purified with
density-gradient centrifugation. Cytosolic pH was measured with single-cell
fluorescence imaging using the pH-sensitive dye
biscarboxyethyl-carboxyfluorescein. RESULTS: Exudative PMNs showed impaired
pHi recovery from an induced acid load compared with circulating PMNs.
Under conditions of extracellular acidosis, exudative PMNs showed impaired
pHi homeostasis and produced decreased superoxide compared with circulating
cells. Inhibition of the sodium-proton exchanger attenuated the differences
in pHi recovery, suggesting a mechanism underlying the pHi regulatory
dysfunction. All cells had comparable adenosine triphosphate levels and
superoxide production at physiologic extracellular pH. CONCLUSION: Impaired
pHi regulation of exudative cells may mediate cellular dysfunction and
impaired resolution of infection at inflammatory sites.
