Human intestinal potential difference: recording method and biophysical implications.

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Abstract
The transmural electrical potential difference (PD) of the intact human small intestine was recorded with close attention to electrical symmetry, shielding from electromagnetic waves and correction for junction potentials. The PD is -12 mV (mucosa-negative) in the fasting jejunum and ileum and does not change during perfusion with isotonic NaCl. Absorption of Na and Cl appears to be non-electrogenic, and the resting PD is probably generated by active anion secretion of fasting intestinal contents. Diffusion potentials during isotonic D-mannitol perfusion indicated higher cation selectivity in the ileum than in the jejunum. The calculated contribution of a free-solution path to total paracellular permeability is 55% in the jejunum and 15% in the ileum. No streaming potential was detected during osmotic water flow, suggesting that the cation-selectivity of the channels is temporarily inactivated during dilatation of the lateral intercellular space.