Release of vasoactive intestinal polypeptide by electrical field stimulation of rabbit ileum

The release of vasoactive intestinal polypeptide (VIP) induced by electrical field stimulation (EFS) of rabbit ileum was studied in vitro. EFS parallel to the muscularis propria caused a significant increase in VIP concentration in the buffer bathing the serosal surface of full-thickness ileum. This effect was blocked by 10(-7) M tetrodotoxin. When circular and longitudinal muscle was removed, the amount of measurable VIP in the tissue decreased to about one-half that of full-thickness ileum, and EFS no longer caused release of VIP into the serosal or mucosal buffers. Our data indicate that EFS of rabbit ileum causes release of VIP, presumably form VIP-containing nerves present in the tissue. These results support the idea that VIP may be a physiological neuroregulator of intestinal function.