The role of the L-arginine-nitric oxide pathway for peristalsis in the opossum oesophageal body.
BACKGROUND
The aim of the study was to determine the effect of NG-nitro-L-arginine (L-NNA), an inhibitor of nitric oxide (NO) synthesis, on primary peristalsis in the oesophageal body.


METHODS
Peristalsis was induced by pharyngeal stroking in 14 lightly anaesthetized opossums. Oesophageal pressures were monitored with a four-channel, perfused catheter assembly and registered with external transducers 1, 4, 7, and 10 cm proximal to the oesophagogastric junction. Propagation time was the time taken for a contraction to travel between two recording sites and was determined in the proximal, middle, and distal parts of the oesophagus (propagation time between 10 and 7 cm, 7 and 4 cm, and 4 and 1 cm recording sites, respectively).


RESULTS
L-NNA (10(-7)-10(-5) mol/kg) dose-dependently reduced propagation time of the contraction in the distal oesophagus from 1.13 +/- 0.24 sec to 0.27 +/- 0.19 sec, whereas propagation in the proximal and middle parts of the oesophagus was unaffected. NG-nitro-D-arginine (D-NNA; 10(-5) mol/kg) had no influence on propagation time. In animals treated with L-NNA (10(-5) mol/kg) atropine (50 micrograms/kg) had no influence on propagation time in any part of the oesophagus. L-Arginine (10(-4) mol/kg) had no influence on the propagation time in animals treated with L-NNA (10(-5) mol/kg) and atropine (50 micrograms/kg). Neither D-NNA (10(-5) mol/kg) nor L-NNA (10(-7)-10(-5) mol/kg) influenced the amplitude of the contractions at any of the recording sites. In animals given L-NNA (10(-5) mol/kg) atropine (50 micrograms/kg) reduced the amplitude of the contraction significantly only at the distal recording site (1-cm recording site) from 62.0 +/- 4.9 mmHg to 34.5 +/- 5.3 mmHg. L-Arginine (10(-4) mol/kg) had no effect on the amplitude of contractions.


CONCLUSIONS
The L-arginine-NO pathway plays a role in the control of primary peristalsic contractions of the oesophagus.
Knudsen
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A
Dept. of Surgical Gastroenterology L, Aarhus Kommunehospital, Denmark.
Frøbert
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O
Tøttrup
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A
D000594:Amino Acid Oxidoreductases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000704:Analysis of Variance; D000818:Animals; D001120:Arginine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004947:Esophagus / Q000187:drug effects* / Q000294:innervation / Q000502:physiology*; D005260:Female; D008297:Male; D009569:Nitric Oxide / Q000037:antagonists & inhibitors* / Q000378:metabolism; D019001:Nitric Oxide Synthase; D019335:Nitroarginine; D009893:Opossums; D010528:Peristalsis / Q000187:drug effects
D019335:Nitroarginine; D009569:Nitric Oxide; D001120:Arginine; D019001:Nitric Oxide Synthase; D000594:Amino Acid Oxidoreductases