THE ELECTRICAL POTENTIAL DIFFERENCE GENERATED BY THE LARGE INTESTINE: ITS RELATION TO ELECTROLYTE AND WATER TRANSFER*

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Abstract
An electrical potential difference of 10 to 40 millivolts was measured across the large intestine of the anesthetized dog, the lumen being negative. Simultaneously, the net transfer of water, Na, K, Cl and bicarbonate between lumen and blood were determined. The unidirectional movements of sodium and chloride were calculated from the rate of absorption of their isotopes. Correlating the electrical potential difference with chemical changes demonstrated evidence for active sodium absorption and bicarbonate secretion (or hydrogen absorption). Potassium secretion and chloride absorption were in the direction of their electrical but opposite to their chemical gradients.