Possible functioning of active ion transport mechanism in the mucous epithelial cells of newt stomach at low temperature.

The membrane potential of mucous epithelial cells of isolated newt stomach was -23 mV on the average at 7 degrees C. The potential decreased when the temperature was lowered further, the normal external solution was replaced with K+-free solution, or ouabain or DNP was applied. The decreased membrane potential level of the cells in K+-free solution was not changed any more by adding ouabain to the solution. The membrane potential increased transiently beyond the control level when the stomach was returned to the normal solution after being exposed to isotonic NaCl solution with EGTA. The transient potential increase was blocked by ouabain. These results suggest that, even at such a low temperature as 7 degrees C, the active ion transport mechanism(s) of mucous epithelial cells in the newt stomach is still capable of functioning to some extent.