Comparison of the inhibitory effects of spermine, papaverine and adrenaline upon isolated segments of the rat small intestine.

In the rat isolated duodenal and ileal segments the active baseline force and spontaneous contractile frequency were inhibited by spermine; the relative potencies, estimated as an ED50, were adrenaline papaverine spermine. The changes in baseline force, but not frequency, due to spermine were sensitive to increased calcium. The duodenum was always more sensitive to papaverine and adrenaline, but the relative sensitivities of the duodenum and ileum were essentially equal for spermine. Inasmuch as the gastrointestinal mucosa of most species contains an abundance of polyamines, these results suggest that, in its free form, spermine may subserve a functional role in the inhibition of gastrointestinal motility.