Reflex Adrenergic Inhibition of Gastric Motility by Nociceptive Intestinal Stimulation and Peritoneal Irritation in the Cat

Abstract

The effects on gastric motility of nociceptive stimulation to jejunum and colon were studied in vagotomized anesthetized cats. Mechanical nociceptive stimulation and diathermy of the jejunum and proximal colon elicited reflex gastric inhibition that was significantly more pronounced than that obtained by stimulation of distal colon. Similarly differentiated reflex responses were induced by electric afferent stimulation of nerves from the respective intestinal segments. Strong nociceptive stimuli from the abdominal cavity, induced by peritonitis, completely blocked vagal excitatory influences on gastric motility, as did multiple nerve stimulation. The gastric inhibitory response to abdominal irritation persisted after adrenalectomy but was eliminated during spinal anesthesia or adrenergic blockade. During gastric suppression in animals with abdominal peritonitis cholinergic potentiation with synstigmin administration could only modestly increase gastric tone. It is concluded that intestinal nociceptive stimulation causes gastric inhibition via sympathetic reflex arches that are segmentally differentiated. These adrenergically mediated inhibitory reflexes are powerful enough to block completely myenteric cholinergic neurons. The results suggest that adrenergic blockade or spinal anesthesia is the logical procedure for treating postoperative adrenergic gastric inhibition. The presently studied sympatho-sympathetic adrenergic reflexes seem to work in synergism with sympatho-vagal nonadrenergic reflexes in suppressing gastric motility during paralytic ileus.

Key-words:

• Adrenergic nerves
• gastrointestinal motility
• paralytic ileus
• peritonitis
• postoperative complications
• spinal cord
• splanchnic nerves
• stomach