Abstract

Kinetic analysis of the accumulation of ³H-choline by innervated longitudinal muscle minces of guinea-pig small intestine disclosed the presence of two distinct choline transport systems, a high affinity component with a K_m of 2 to 4 µM and a low affinity component with a K_m of 90 to 100. µM. Removal of the myenteric plexus greatly reduced the velocity of choline transport at low concentrations of ³H-choline. In muscle minces devoid of plexus, the high affinity choline transport component was no longer detectable, whereas the low affinity transport of choline persisted. It is concluded that the intestinal neuronal elements possess a specialized high affinity mechanism for the rapid and efficient transport of choline and its conversion into acetylcholine.