Water and electrolyte transport by rabbit esophagus

The nature of the transmural electrical potential difference and the characteristics of water and electrolyte transport by rabbit esophagus were determined with in vivo and in vitro studies. The potential difference of the perfused esophagus in vivo was -28 ± 3 mV (lumen negative). In vitro the potential difference was -17.9 ± 0.6 mV, the short circuit current 12.9 ± 0.6 μA/cm², and the resistance 1,466 ± 43 ohm.cm². Net mucosal to serosal sodium transport from Ringer solution in the short circuited esophagus in vitro accounted for 77% of the simultaneously measured short circuit current and net serosal to mucosal chloride transport for 14%. Studies with bicarbonate free, chloride free, and bicarbonate chloride free solutions suggested that the net serosal to mucosal transport of these two anions accounts for the short circuit current not due to sodium absorption. The potential difference and short circuit current were saturating functions of bathing solution sodium concentration and were inhibited by serosal ouabain and by amiloride. Thus active mucosal to serosal sodium transport is the major determinant of the potential difference and short circuit current in this epithelium.