Electrical potentials across isolated small intestine of the rat

Electrical potential measurements indicated that the absorption of salt across the small intestine was the result of active transport of Na + , followed passively by an equivalent of Cl – . The potential across the intestine was positive on the serosal side and higher in the jejunum than in the ileum. The Na + concentration in the bathing media determined the magnitude of the potential; other monovalent ions had no effect.