Abstract
1. The sugar-induced change in transmural potential was recorded in vitro from everted small intestines taken from hibernating toads and the characteristics of the potential change were studied under various external conditions.
2. Qualitatively, the sugar-evoked potential of toad intestine had characteristics quite similar to those seen in mammalian intestine, and it was intimately related to the active sugar transport.The size of the glucose-evoked potential revealed a Michaelis-Menten like relationship with external Na and glucose concentrations, the apparent Km values for glucose and Na being dependent on the Na and glucose concentrations of the medium, respectively.
3. The portion of the intestine capable of producing a large sugar-evoked potential was confined to the upper small intestine, where the affinities for glucose and Na were remarkably high in comparison with intestines of other animals.
4. The size of the glucose-evoked potential linearly increased as temperature or pH of the medium was elevated in the temperature range of 4-32°C and in the pH range of 6.6-8.2.
