AJP - Cell Physiology, Vol 254, Issue 2 C272-C285, Copyright © 1988 by American Physiological Society

ARTICLES

Assessment of Na+-H+ exchange activity in phagosomal membranes of human neutrophils

S. Grinstein and W. Furuya
Department of Cell Biology, Hospital for Sick Children, Toronto, Ontario, Canada.

To assess the presence of Na+-H+ exchange in internalized membranes, the phagosomal pH was monitored in suspensions of intact human neutrophils by measuring the fluorescence of ingested bacteria (Micrococcus lysodeikticus) prelabeled with a pH-sensitive dye. Uptake of fluoresceinated bacteria was confirmed by flow cytometry and by phase-contrast and electron microscopy. Manipulation of the cytoplasmic ion content was accomplished by permeabilization of the plasma membrane with nystatin, which did not alter phagosomal permeability. At 37 degrees C, the phagosomal interior acidified at a maximal rate of 0.135 +/- 0.003 pH units/min (n = 10). The endogenous Na+-H+ exchanger does not affect phagosomal acidification, since the rate and extent of the pH change were not altered by 1) omission of intraphagosomal Na+ and 2) addition of the permeant inhibitor methylisobutylamiloride or by trapping amiloride in the phagosome during bacterial ingestion. Moreover, amiloride-sensitive Na+-H+ exchange was not detectable when Na+ or H+ gradients were imposed across the phagosomal membrane. Under comparable conditions, Na+-H+ exchange could be readily detected across the surface membrane. These data imply that the Na+-H+ antiporters are either inactivated in the phagosome or are segregated and not internalized into the phagosomal membrane.

This article has been cited by other articles:

				H. Morihata, F. Nakamura, T. Tsutada, and M. Kuno Potentiation of a Voltage-Gated Proton Current in Acidosis-Induced Swelling of Rat Microglia J. Neurosci., October 1, 2000; 20(19): 7220 - 7227. [Abstract] [Full Text] [PDF]

				A. Punturieri, S. Filippov, E. Allen, I. Caras, R. Murray, V. Reddy, and S. J. Weiss Regulation of Elastinolytic Cysteine Proteinase Activity in Normal and Cathepsin K-deficient Human Macrophages J. Exp. Med., September 11, 2000; 192(6): 789 - 800. [Abstract] [Full Text] [PDF]

				I. Bize, B. Guvenc, A. Robb, G. Buchbinder, and C. Brugnara Serine/threonine protein phosphatases and regulation of K-Cl cotransport in human erythrocytes Am J Physiol Cell Physiol, November 1, 1999; 277(5): C926 - C936. [Abstract] [Full Text] [PDF]

				S. J. Wadsworth and H. Goldfine Listeria monocytogenes Phospholipase C-Dependent Calcium Signaling Modulates Bacterial Entry into J774 Macrophage-Like Cells Infect. Immun., April 1, 1999; 67(4): 1770 - 1778. [Abstract] [Full Text] [PDF]

				B. Leblebicioglu and J. Walters Alkaline Conditions Accelerate Polymorphonuclear Leukocyte Apoptosis In Vitro Infect. Immun., April 1, 1999; 67(4): 2019 - 2021. [Abstract] [Full Text] [PDF]

				E. Krump, K. Nikitas, and S. Grinstein Induction of Tyrosine Phosphorylation and Na+/H+ Exchanger Activation during Shrinkage of Human Neutrophils J. Biol. Chem., July 11, 1997; 272(28): 17303 - 17311. [Abstract] [Full Text] [PDF]