EXPERIMENTAL STUDY OF GASTRIC ACTIVITY RELEASED FROM CORTICAL CONTROL

Abstract

Graphic studies of gastric and oesophageal activity were made in 6 cats before and after successive removal of the cerebral motor cortices. A balloon attached to the tip of a small catheter was introduced through the mouth into the stomach and inflated with air in 20 c.c. increments. The catheter was connected over a closed water reservoir communicating with a manometer. Fluctuations of pressure in the stomach balloon were transmitted to an air tambour connected with the manometer and recorded kymographically. The tracings therefore represented a constantly changing summation of all smooth muscle activity in the stomach wall. Animals were immobilized with bulbocapnine which produced a cataleptic-like state without interfering significantly with peristalsis. Definite alterations in gastric activity followed ablation of the motor cortices and were demonstrable as greater persistency, consistency and strength of stomach contractions along with increased tone throughout distension. This was interpreted as evidence of release from a regulating influence by the motor cortex. A marked stretch reflex with delayed relaxation of the stomach wall after sudden distention was also apparent. In the oesophagus similar changes occurred after operation as increased wave amplitude, regularity and persistency and as an elevation of tone An attempt was made to correlate the results of the present study with those made earlier on micturition released from cerebral control. It was suggested that the smooth muscle of the stomach and oesophagus is controlled by reflex pathways in the nervous system similar to those which control tone and contraction in the vesical muscle.