| Abstract: | A detailed examination of the effects of exogenous arachidonate on cation metabolism in rabbit neutrophils was undertaken. Arachidonic acid stimulates the movement of 45Ca into and out of the neutrophils with a net result, in the presence of extracellular calcium, of increasing the steady-state level of 45Ca. Arachidonate also increases the uptake of 22Na. These effects of arachidonate are specific to these cations, concentration-dependent, and sensitive to lipoxygenase inhibitors. At the concentrations used in this study arachidonate does not influence the permeability of human erythrocytes to 45Ca. Furthermore, both arachidonic acid and F-Met-Leu-Phe release calcium from a previously unexchangeable intracellular pool and the effect of the two stimuli are not additive. Arachidonic acid-dependent, but not F-Met-Leu-Phe-dependent, calcium release is sensitive to lipoxygenase inhibitors. These two stimuli thus appear to release is sensitive to lipoxygenase inhibitors. These two stimuli thus appear to release calcium from the same pool(s) by separate mechanisms. The results summarized above are consistent with the hypothesis that one or more arachidonate metabolites are involved in the mechanism underlying the chemotactic factor induced permeability changes in rabbit neutrophils. |
