The effect of theophylline on glucose and fluid transport across the rat jejunum.

The net absorption of fluid and electrolytes by the mammalian small intestine may be changed to a state of net secretion by the administration of agents that elevate the cyclic AMP content of the mucosal epithelium, e.g. cholera toxin, theophylline, dibutyrylcyclic AMP [for reviews see Banwell &Sherr(1973),Sladen(1973), Field(1974) and Kimberg (1974)l. In contrast with the wealth of data on the movements of electrolytes across the small intestine in the presence of these agents, there has been little work on the ways in which sugar and amino acid transport are affected by secretory stimuli. This is surprising in that the movements of non-electrolytes are thought to be tightly coupled to the movement of ions, in particular sodium. The present communication examines the effect of theophylline on glucose and fluid transport across an intact preparation of the rat jejunum in vitro. Isolated segments of rat jejunum, 20-30cm long, were perfused through the lumen in a gas-lift apparatus similar to that of Fisher & Parsons (1949). The loops were suspended in liquid paraffin, and transported fluid, exuded at the serosal surface of the gut, appeared as droplets of liquid, which sank beneath the liquid paraffin and could be collected for volume measurement and glucose analysis. The segments were incubated