A novel method to assess gastric accommodation and peristaltic motility in conscious rats

To simultaneously study gastric accommodation and peristaltic motility in the whole stomach of conscious rats by measuring intragastric pressure (IGP) during test-meal infusion.

After an overnight fast, a test-meal infusion system and a catheter to measure IGP were connected to a chronically implanted gastric fistula. IGP was measured during infusion of an X-ray-opaque, non-nutritious viscous test meal (0.25-2 ml min(-1)); gastric motility and emptying were assessed by X-ray fluoroscopy. Peristaltic motility-induced IGP waves were quantified as a motility index (wave amplitude divided by wavelength). Experiments were performed in Sprague-Dawley (SD) rats and in the high-anxiety Wistar Kyoto (WKY) rats. Moreover, the effects of 30 mg kg(-1) NG-nitro-L-arginine methyl ester (L-NAME), 1 mg kg(-1) atropine or 20 mg kg(-1) molsidomine were tested in SD rats.

Compared with SD rats, IGP increased significantly faster during stomach distension in WKY rats, indicating impaired accommodation in the latter strain. Motility indices did not differ between the two strains. L-NAME significantly increased IGP during stomach distension, indicating decreased gastric accommodation. However, no change in motility indices was observed with L-NAME. Treatment with atropine significantly increased IGP and decreased motility indices, indicating decreased gastric accommodation and motility. Molsidomine significantly decreased IGP during stomach distension but did not affect motility. The results correspond to X-ray observations, and confirm literature data.

We conclude that IGP measurement during test-meal infusion represents an efficient and novel method to compare gastric accommodation and peristaltic motility in the whole stomach of conscious rats.