Exocytotic enzyme release from rabbit polymorphonuclear leukocytes after treatment with fluoride and calcium

Abstract

Treatment of rabbit polymorphonuclear leukocytes (PMNs) with 20 mM sodium fluoride for 10 min, followed by removal of fluoride and addition of Ca 2+ results in extensive exocytosis. This is apparent from a strong lysozyme release, together with a slight LDH release. During fluoride-activated Ca 2+-dependent exocytosis an increase of indo fluorescence and a strong association of 45Ca with the cells occurs. Different inhibitors inhibit both 45Ca association and lysozyme release. Pretreatment of PMNs with pertussis toxin, or the presence of Al 3+ in the medium has little effect on fluoride-activated Ca 2+-dependent exocytosis. During pretreatment with fluoride, the ATP level strongly decreases. Exocytosis nevertheless occurs upon addition of Ca 2+, indicating that a normal ATP level is not required for exocytosis. The glycogen content of the cell strongly decreases during exposure to Ca 2+ after pretreatment with fluoride, but not during pretreatment with fluoride. Breakdown of glycogen and accumulation of 3-phosphoglycerate suggest that glycolysis is blocked at the enolase step, but proceeds as far as that step.