Na+-Dependent Ca2+ Transport Modulates the Secretory Response to the Fcϵ Receptor Stimulus of Mast Cells

摘要: Immunological stimulation of rat mucosal-type mast cells (RBL-2H3 line) by clustering their Fcepsilon receptors (FcepsilonRI) causes a rapid and transient increase in free cytoplasmic Ca(2+) ion concentration ([Ca(2+)](i)) because its release from intracellular stores. This is followed sustained elevated [Ca(2+)](i), which attained influx. Because an FcepsilonRI-induced the membrane permeability for Na(+) ions has also been observed, secretion at least partially inhibited lowering extracellular sodium concentrations ([Na(+)](o)), operation Na(+)/Ca(2+) exchanger considered. We found significant coupling between gradients across plasma membranes RBL-2H3 cells, we investigated employing (23)Na-NMR, (45)Ca(2+), (85)Sr(2+), Ca(2+)-sensitive fluorescent probe indo-1. The reduction ([Ca(2+)](o)) provoked [Na(+)](i) increase, decrease [Na(+)](o) results influx as well [Ca(2+)](i). Mediator assays, monitoring released beta-hexosaminidase activity, showed presence sigmoidal dependence on [Ca(2+)](o). However, was not affected varying [Ca(2+)](o) lowered to 0.4 mM, while it almost completely = 136 mM < 0.05 mM. Increasing caused reach minimum 20 steady maximum value A parallel fluxes observed: Antigen pronounced At 17 only slight efflux detected, whereas no transport cell could be observed. Our clearly indicate that secretory response FcepsilonRI due influence mediated Na(+)-dependent transport.