Na+ transport processes in isolated guinea pig nasal gland acinar cells

Publisher Website
Google Scholar
Abstract
In the dispersed acinar cells of the submucosal nasal gland in the guinea pig, intracellular Na+ concentration ([Na+]i) was measured with a microfluorimetric imaging method and the cytosolic indicator dye, sodium-binding benzofuran isophthalate, under HCO3−-free conditions. In the unstimulated condition, the [Na+]i was averaged to 12.8 ± 5.2 mM. Addition of 100 μM ouabain or removal of external K+ caused an increase in [Na+]i. Replacement of external Cl− with NO3− or addition of 0.5 mM furosemide reversibly decreased the [Na+]i. The recovery process from the reduced [Na+]i was inhibited by removal of either K+ or Cl− in the bath solution. These findings indicate the presence of a continuous influx of Na+ coupled with K+ and Cl− movement. Application of acetylcholine (ACh, 1 μM) caused an increase in [Na+]i by about 15–20 mM, which was completely inhibited by addition of 10 μM atropine. Increased cytosolic Na+ induced by ACh was extruded by the Na+-K+ pump. Removal of external Cl− and addition of 50 μM dimethylamiloride inhibited ACh-induced increase in [Na+]i by about 66% and 19%, respectively. In both unstimulated and stimulated state, Na+-K+ pump, Na-K-Cl cotransport, and Na+-H+ exchange play a critical role in maintaining intracellular electrolyte environment and in controlling a continuous secretion of nasal fluids.