Effects of Vasopressin, Theophylline and Cyclic Adenosine Monophosphate on Short-circuit Current across Isolated Rabbit Ileal Mucosa

Abstract

VASOPRESSIN causes rapid, equal increases in short-circuit current (Isc) and rate of transport of sodium when added to the serosal surface of frog skin or toad bladder^1,2. Several investigators have presented convincing evidence that this alteration in the active transport of sodium is primarily, if not entirely, a consequence of increased passive permeability of the mucosal surface to sodium, as well as to other small hydrophilic solutes^3–5. Adenosine-3′,5′-monophosphate (cyclic AMP) and theophylline have been shown to mimic the effects of vasopressin on Isc and osmotic water flow across toad bladder⁶. It has been suggested that cyclic AMP is the more direct mediator of the permeability change and that vasopressin and theophylline exert their effects by increasing the concentration of cyclic AMP in the epithelial cells⁷.