Relationship between intestinal motility, tone, water absorption and lymph flow in the rat

The relations between motility, tone, water absorption rate (Jv) and lymph flow (J1), were studied in an exteriorized upper jejunal preparation in vivo, with its serosal side bathed in Krebs-Ringer or other solutions. Neither Jv nor J1 was correlated with motility. When the luminal fluid consisted of an isotonic solution of MgSO4, glucose or LiCl, motility was greatly increased with no increase in J1. When the serosal fluid consisted of an isotonic solution of mannitol, glucose or MgSO4, motility was depressed with a large decrease in tone, and Jv was increased by 51-83% with a decrease in J1. When the serosal fluid consisted of an isotonic solution of NaCl, Na2SO4, LiCl or KCl, motility was decreased with either no change or an increase in tone, and both Jv and J1 were much decreased. When isotonic choline Cl solution was employed as the serosal fluid, motility increased with an increase in tone, Jv became negative (fluid secretion), and J1 decreased to 0. Acetylcholine depressed motility but increased tone with a decrease in Jv and J1. Eserine increased both tone and motility with a decrease in Jv and J1. Serotonin caused no change in motility but increased tone with a decrease in Jv and J1. Noradrenaline and adrenaline depressed motility and reduced tone with an increase in Jv and J1. Isoprenaline abolished motility and reduced tone with a large increase in Jv but no change in J1. Pentobarbitone depressed motility and reduced tone with an increase in Jv but a decrease in J1. It is concluded that the intestine responds to various stimuli with a change in motility, or tone, or both. Intestinal motility per se does not produce lymph. Since an increase or decrease in tone always results in a decrease or increase in Jv, respectively, regardless of the nature of the conditions, a relaxation of the intestinal musculature appears to be associated with an increase in water absorption.