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  • Title: A role for the sodium, potassium adenosine triphosphatase (Na+,K+ ATPase) enzyme in degranulation of rat basophilic leukaemia cells.
    Author: Gentile DA, Skoner DP.
    Journal: Clin Exp Allergy; 1996 Dec; 26(12):1449-60. PubMed ID: 9027446.
    Abstract:
    BACKGROUND: A circulating inhibitor of the sodium, potassium adenosine triphosphatase (Na+,K+ ATPase) enzyme has been described in allergic subjects. Recent studies have suggested that the Na+,K+ ATPase, enzyme may be involved in the signal transduction pathways of various cell types and that inhibition of its activity can modulate histamine release from basophils and mast cells. OBJECTIVE: The purpose of this study was to determine if modulation of Na+,K+ ATPase activity alters degranulation in the 2H3 subline of rat basophilic leukaemia cells (RBL-2H3), a mucosal mast cell model bearing high-affinity Fc receptors for IgE. METHODS: Degranulation was measured by the release of both exogenous serotonin and endogenous histamine. Na+,K+ ATPase activity was assessed by ouabain-sensitive [86rubidium] uptake ([86Rb] uptake) and ex situ enzyme activity. RESULTS: Ouabain-sensitive [86Rb] uptake and degranulation increased in parallel and in a dose-response fashion with increasing Fc receptor cross-linking. Additionally, incubation with ouabain, a known inhibitor of Na+,K+ ATPase activity, decreased both anti-IgE and calcium ionophore-induced degranulation, but increased spontaneous degranulation, each in a dose-response manner. Moreover, the effect of ouabain on degranulation was reversed by rinsing and mimicked by other known inhibitors of Na+,K+ ATPase activity. Finally, in the absence of anti-IgE or calcium ionophore, stimulation of ouabain-sensitive [86Rb] uptake by the sodium (Na+) ionophore monensin was associated with a corresponding dose-response increase in ouabain-sensitive degranulation. These experiments demonstrate that ouabain-sensitive [86Rb] uptake increases following IgE receptor cross-linking in RBL-2H3, and that factors which modulate Na+,K+ ATPase activity in these cells may also regulate degranulation. CONCLUSION: The results of this study suggest an important role for Na+,K+ ATPase activation in the signal transduction pathway of stimulated RBL-2H3.
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