Chloride-dependent electrogenesis by the anterior intestine of Achatina fulica

Abstract

The serosal side of the anterior intestine of the giant African snail, Achatina fulica, is a few millivolts negative to the mucosal side in vivo and in vitro. The potential difference ranged from 1.0 to 7.5 mV (average 2.8 ± 1.4 mV) and the short-circuit current difference, from 28.0 to 150.0 μA/cm2 (average 75.0 ± 12.8 μA/cm2). Good stirring is essential for the maintenance of the electrical gradient in vitro. The electrical potential does not depend on K+, Mg2+, Ca2+, or Na+ but requires Cl− on the mucosal side. The electrical gradient is reduced by cyanide, 2,4-dinitrophenol, and anoxia but not by ouabain, furosemide, or bumetanide. The transmural potential difference and short-circuit current were predominantly dependent upon aerobic metabolism. However, a finite residual component was dependent upon glycolytic energy. It is concluded that the role of chloride transport across the intestinal epithelium may be to facilitate fluid absorption from the lumen into the haemolymph.