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Characterization of vagal pathways mediating gastric accommodation reflex in rats
Author(s) -
Takahashi Toku,
Owyang Chung
Publication year - 1997
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j.1469-7793.1997.479be.x
Subject(s) - gastric distension , distension , hexamethonium , guanethidine , reflex , stomach , medicine , endocrinology , vagotomy , chemistry , anesthesia , stimulation
1 We investigated the vagal pathways mediating the gastric accommodation reflex in the rat stomach. 2 Gastric distension (6 ml) evoked an increase of 9.0 ± 1.0 cm H 2 O of intragastric pressure in vivo. Pretreatment with tetrodotoxin (TTX) caused a significant pressure increase by gastric distension, reaching 17.0 ± 1.7 cm H 2 O, suggesting mediation by neural pathways. 3 The pressure increase evoked by gastric distension was significantly enhanced in vivo by acute truncal vagotomy (TV), hexamethonium (C6), and N G ‐nitro‐L‐arginine methyl ester ( l ‐NAME), but not by vasoactive intestinal polypeptide (VIP) antiserum, guanethidine, or splanchnicotomy. 4 Gastric distension (6 ml) evoked a much larger intragastric pressure in the denervated, vascularly isolated, perfused rat stomach in vitro. Intra‐arterial application of TTX and l ‐NAME did not cause further pressure increases evoked by gastric distension. 5 The pressure increase evoked by gastric distension remained high 2 weeks after TV in vivo. However, the accommodation reflex was fully restored 4 weeks after TV in vivo. This reflex was antagonized by TTX, C6 and l ‐NAME, but not by VIP antiserum, guanethidine and splanchnicotomy. 6 Similar to in vivo studies, gastric distension caused a smaller increase in intragastric pressure in response to gastric distension in the denervated, vascularly isolated, perfused stomach obtained from rats 4 weeks after vagotomies in vitro. The pressure increase evoked by gastric distension was significantly enhanced by l ‐NAME, hexamethonium and TTX. 7 It is suggested that the vago‐vagal reflex plays an important role in mediating the accommodation reflex. This involves a vagal efferent pathway that uses nitric oxide as a final neurotransmitter mediating gastric relaxation in intact rats. It is also suggested that the adaptive mechanism mediating the accommodation reflex following vagotomy occurs in the gastric myenteric plexus.