AJP - Lung Cellular and Molecular Physiology, Vol 260, Issue 6 464-L470, Copyright © 1991 by American Physiological Society

ARTICLES

Heterogeneity in superoxide production as measured by nitro blue tetrazolium reduction from individual PAM

K. A. DiGregorio, E. V. Cilento and R. C. Lantz
Department of Chemical Engineering, West Virginia University, Morgantown 26506-6101.

Heterogeneity in superoxide (O2-.) production (as determined by the reduction of nitro blue tetrazolium to a diformazan precipitate), cell volume, and cell spreading were measured from single rat pulmonary alveolar macrophages (PAM). Of the 330 cells that produced O2-. due to stimulation by adherence, the maximum diformazan produced (MAX) varied between 1.8 and 47.2 fmol and the maximum (initial) rate of diformazan production (R) varied between 2.2 and 81.7 X 10(-3) fmol/s. Only six PAM of 336 analyzed failed to produce O2-. suggesting that O2-. production is not a specific function of a small subpopulation of PAM but rather that all PAM are capable of producing O2-.. Importantly, O2-. production by single cells showed extensive heterogeneity that did not correlate (r2 less than 0.12) with individual cell volumes, suggesting that the observed heterogeneity may not be due to differences in maturation and/or differentiation. However, when the single cell data were grouped into cell volume subfractions small but increasing linear trends (r2 greater than 0.81) in MAX and R were found. This discrepancy suggests that PAM heterogeneity in O2-. fraction cannot be estimated adequately by measurements on subpopulations of cells.

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