Effect of substance P on the lower esophageal sphincter of the opossum

Gastroenterology. 1978 Aug;75(2):278-82.

Abstract

Since the original observations by Von Euler and Gaddum, considerable interest has developed regarding the role of substance P in smooth muscle function. The purpose of the present investigation was to evaluate the effect of intravenously administered substance P on the vivo motor function of the lower esophageal sphincter (LES). Intraesophageal pressures were monitored by an assembly of polyvinyl catheters attached to pressure transducers and a recorder. The catheters were continuously perfused with bubble-free water. Administration of 5, 10, 25, 50, and 100 ng per kg of substance P stimulated the LES, respectively, 16, 32, 57, 147, and 169% above control values. Tetrodotoxin, phentolamine, hexamethonium, methysergide, and bilateral cervical vagotomy did not alter the response of the LES to substance P. Atropine in 40-, 250-, and 500-microgram per kg doses significantly but partially inhibited the response of the LES to substance P. It is concluded that subtance P is a potent stimulant of the LES. The stimulatory effect of substance P may involve both cholinergic muscarinic and noncholinergic mechanisms. It is conceivable that substance P may be a modulator of LES pressure, although the exact physiological significance is not clear at the present time.

MeSH terms

  • Animals
  • Atropine / pharmacology
  • Esophagogastric Junction / drug effects
  • Esophagogastric Junction / physiology*
  • Female
  • Hexamethonium Compounds / pharmacology
  • Male
  • Manometry
  • Methysergide / pharmacology
  • Opossums
  • Phentolamine / pharmacology
  • Substance P / pharmacology*
  • Vagotomy
  • Vagus Nerve / physiology

Substances

  • Hexamethonium Compounds
  • Substance P
  • Atropine
  • Methysergide
  • Phentolamine