Exudative neutrophils show impaired pH regulation compared with circulating neutrophils.
OBJECTIVE
To investigate the effects of neutrophil (PMN) transmigration into inflammatory sites on cytosolic pH (pHi) regulation.


METHODS
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.


CONCLUSIONS
Impaired pHi regulation of exudative cells may mediate cellular dysfunction and impaired resolution of infection at inflammatory sites.
Hackam
D J
DJ
Department of Surgery, Toronto Hospital, University of Toronto, Ontario.
Grinstein
S
S
Nathens
A
A
Watson
W G
WG
Marshall
J C
JC
Rotstein
O D
OD
D000138:Acidosis / Q000378:metabolism; D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology*; D005122:Exudates and Transudates / Q000166:cytology*; D006706:Homeostasis; D006863:Hydrogen-Ion Concentration; D009504:Neutrophils / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley