Oxidative metabolic responses of rabbit pulmonary alveolar macrophages

Abstract

During phagocytosis of opsonized lipopolysaccharide-coated paraffin oil droplets, rabbit alveolar macrophages reduced nitroblue tetrazolium, which effect was in part inhibitable with the use of superoxide dismutase. Exposure of cytochalasin-B-treated rabbit alveolar macrophages to opsonized zymosan led to the generation of superoxide, as quantitated by ferricytochrome C reduction. It was found that nitroblue tetrazolium in the presence of ferricytochrome C could in turn serve as scavenger of superoxide during stimulation of cytochalasin-B-treated rabbit alveolar macrophages. Following challenge with either opsonized zymosan or the membrane perturbant digitonin, rabbit alveolar macrophages released hydrogen peroxide into the extracellular medium. Employment of the surface membrane stimulant phorbol myristrate acetate led to activation of the hexose monophosphate shunt, which activity could be further enhanced in the presence of superoxide dismutase or attenuated in the presence of catalase. These studies demonstrate that rabbit alveolar macrophages release superoxide and hydrogen peroxide during surface membrane perturbation. In turn, hydrogen peroxide generation can stimulate the hexose monophosphate shunt.