Abstract

Changes in intragastric pressure after dorsal truncal vagotomy, investigated by stimulation of the surviving vagal branches and by step inflation of the stomach, were divided into an early phase lasting five days, and a late phase continuing for at least three months. During the early phase the amplitude of vagal evoked contraction was diminished but the resting pressure and the response to gastric inflation were increased. After the fifth day vagal evoked contractions doubled in amplitude but the resting pressure and the response to step inflation of the stomach returned to control levels. Ventral vagotomy did not produce any substantial changes. Alterations to gastric and body weight, or to the relation between resting pressure and evoked contraction and relaxation were excluded as causes of the enhanced vagal effectiveness. Sprouting of axons into denervated territory occurred too late to explain the changes, but an increase in synaptic density within the innervated territory has not been ruled out.