36Cl − and 86Rb + uptake in rat parotid acinar cells

Abstract

36Cl − uptake was markedly (85 per cent) inhibited by the loop diuretics, furosemide and bumetanide. Partial replacement of Na + in the incubation medium (from 137 to 50 mM) reduced 36Cl − uptake 30 per cent; total replacement reduced uptake to 40–45 per cent of control values. Partial replacement of K + (from 5.8 to 1 mM) decreased 36Cl − uptake approx. 45 per cent; complete replacement resulted in minimal levels of 36Cl − uptake (< 10 per cent of controls). Ouabain reduced 36Cl − uptake approx. 55 per cent in the absence of bumetanide, but was without effect in its presence. 86Rb + uptake was reduced approx. 85 per cent with bumetanide; complete replacement of Cl − with I − or gluconate −, decreased 86Rb + uptake by 55 or 40 per cent respectively. The results support the notion that the bulk of Cl − influx in rat parotid acinar cells is via a loop diuretic-sensitive Na +/K +/Cl − co-transport mechanism as may occur in other secretory epithelia.