Changes in the membrane potential, the cytoplasmic Ca2+ concentration and in the transport of fluorescein anions across the macrophage plasma membrane under the influence of O2(-) and H2O2 in small concentrations]

It has been shown that under the influence of superoxide anion (300 nM) and hydrogen peroxide (100 nM) on murine peritoneal macrophages, the depolarization of membrane takes place, and a change in the rate of fluorescein anion efflux from the cells occurs. Hydrogen peroxide (but not superoxide anions) causes a transient increase in the cytoplasmic Ca2+ concentration. These changes are regarded as early signs of macrophage activation. It is assumed that macrophage activation with reactive oxygen intermediates at such a low concentration might be interpreted as follows: a small portion of stimulated phagocytes activates the whole population with the aid of the products of their own oxidative burst.