Iprindole-Induced Phospholipidosis in Rat Alveolar Macrophages: Alterations in Oxygen Consumption and Release of Oxidants

Abstract

Rats chronically treated with the cationic amphipilic drug iprindole developed a phospholipid storage disorder in their pulmonary alveolar macrophages (AMs). AMs from these iprindole-treated rats (IP-AMs) were compared to AMs from control rats (C-AMs) regarding oxygen consumption and the release of two reactive oxygen species, superoxide anion and hydrogen peroxide. Responses of C-AMs and IP-AMs were compared at rest and when stimulated by unopsonized or opsonized zymosan. Opsonization was not necessary in order to induce respiratory burst-associated phenomena in either cell type; in fact in all cases, for a given cell type responses to unopsonized zymosan were virtually identical to those of opsonized zymosan. When at rest, IP-AMs consumed oxygen at a rate nearly identical to that of C-AMs. When stimulated with zymosan particles, IP-AMs consumed more oxygen than controls. However, when superoxide anion and hydrogen peroxide, two products of the respiratory burst were measured, IP-AMs released less of these species than C-AMs when at rest and when particle stimulated. Despite the lower total release of these species by the IP-AMs, the zymosan-induced release (stimulated minus resting levels) was greater for these cells than C-AMs. Therefore, the IP-AMs were found to be more responsive to the zymosan particle than C-AMs. The results indicate marked changes in the release of reactive oxygen species from the AMs following induction of phospholipidosis.