ORAL PROPAGATION OF THE CIRCULAR MUSCLE CONTRACTION INDUCED BY LOCAL DISTENSION OF THE ISOLATED GUINEA PIG ILEUM

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Abstract
The local distension of the intestinal wall was carried out by inflating a thin rubber balloon which had been fixed in the lumen and the contractions of the circular muscle were recorded at the points of 5 mm (PO1) and 20 mm (PO2) oral to the fixed balloon. The contractions elicited by local distension was blocked by tetrodotoxin and atropine, or removing longitudinal muscle, with the myenteric plexus adhering to it, from the intestine at the distending region. When 2 to 3 mm length of longitudinal muscle was stripped off around the intestine between PO1 and PO2, the contraction initiated at PO1 never reached to PO2. That is, the oral contraction did not propagate beyond the myenteric plexus-free region of the segment. When drugs were applied exclusively to the region around PO2, tetrodotoxin and hexamethonium, but not atropine, abolished the contraction at PO2, while the contraction at PO1 was clearly observed. It is likely that the contraction observed at the point of PO2 was evoked by non-cholinergic nervous mechanisms.

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