Endogenous motilin and the LES pressure

The changes in LES pressure were measured after alkalinization and subsequent acidification of the antrum or duodenum. For the alkalinization of the antrum, a strong (sodium-hydroxide) and a weaker alkaline stimulus were used in different subjects. At the end of the experiments, glycine 5% was infused into antrum and glycine 5% or phenylalanine 0.1 N into the duodenum. Plasma samples were drawn for determination of the motilin levels. Although in some experimental situations, motilin levels and LES pressure were significantly correlated, any correlation was lacking in other test situations. It may be concluded that the role of endogenous motilin for the regulation of the LES pressure is either non-existent or frequently overwhelmed by other influences.