Intracellular microelectrode studies of Necturus antral mucosa. Effect of aspirin on cell membrane potentials

Intracellular microelectrode techniques were used to determine the effects of luminal aspirin on epithelial cell membrane potentials of Necturus antral mucosa. In this tissue, prolonged stable intracellular impalements were obtained with 15-50-M omega microelectrodes filled with 3 M KCl. In acidic mucosal solution (pH 4.0) the addition of aspirin at 5.0 mM resulted in a significant decrease of apical cell membrane potential (Vmc) from -36.8 +/- 2.2 to -22.2 +/- 2.1 mV (p less than 0.001) and basolateral cell membrane potentials (Vcs) from -38.8 +/- 1.7 to -25.3 +/- 2.1 mV (p less than 0.001). Upon removal of aspirin from the mucosal solution, both cell membranes hyperpolarized for a brief period before returning to their original potentials. In neutral mucosal solutions (pH 7.0), addition of aspirin (5.0 mM) resulted in a significant increase in apical cell membrane potential (Vmc) from -40.0 +/- 2.4 to -46.8 +/- 3.3 mV (p less than 0.001) and basolateral cell membrane potential (Vcs) from -41.5 +/- 2.0 to -49.7 +/- 2.5 mV (p less than 0.001). This hyperpolarization of the cell was associated with an increase in transmucosal potential from -1.5 +/- 1.8 to -2.9 +/- 1.8 mV (p less than 0.001) and an increase in the ratio of apical to basolateral membrane resistances from 2.2 +/- 0.4 to 3.1 +/- 0.7 (p less than 0.05). These changes in membrane potentials and the ratio of membrane resistances may be caused by a change in ionic conductance of the cell membranes induced by aspirin.