title: Ionic pathways of secretory membrane of frog gastric mucosa in Cl--free media.
abstract: Experiments were performed to determine the return ionic pathways of the secretory membrane of frog gastric mucosa associated with the electrogenic H+ pump in Cl--free media. The replacement of a 52 mM Na2SO4 secretory solution with a 52 mM K2SO4 secretory solution led to a decrease of resistance, an increase of the H+ secretory rate, and a reversal of the PD. The replacement of 52 mM Na2SO4 with 52 mM MgSO4 led to an increase of resistance and a decrease of the H+ rate. These results provided evidence for the existence of K+ and Na+ pathways, the former having a lower resistance than the latter. Short-circuiting the mucosa in Mg2+ solutions increased the H+ rate to the value in Na+ solutions, hence ruling out the possibility that Mg2+ might interfere with the H+ pump. The fact that the Mg2+ secretory solution, without K+ or Na+, did not abolish the H+ rate suggested the presence of at least a third ionic pathway. presumably SO42-, providing that Mg2+ does not penetrate the mucosa.
mesh_terms: D000818:Animals; D001693:Biological Transport, Active; D004594:Electrophysiology; D005753:Gastric Mucosa / Q000378:metabolism / Q000502:physiology*; D006859:Hydrogen / Q000378:metabolism; D066298:In Vitro Techniques; D008274:Magnesium / Q000378:metabolism; D011188:Potassium / Q000378:metabolism; D011894:Rana pipiens / Q000502:physiology*; D013431:Sulfates / Q000378:metabolism
chemical_list: D013431:Sulfates; D006859:Hydrogen; D008274:Magnesium; D011188:Potassium