Abstract
To determine the effect of pressure and stretching on the release of 5-hydroxy--tryptamtne (5-IIT) from the intestinal wall at the time of distension of the lumen, artexperimerrt vvas carried out with the small intestine isolo.ted frorrn a male guinea pig.When pressure and stretching were inflicted upon the intestinal wall, the release of 5-HTfrom the intestinal wall was compared with that taking place when no pressure norstretching had been placed upon the intestinal wall (control). The 5-FIT release in theexperimental group was about 2.5 tirnes as much as that in the control group. Whenpressure alone had been added to the incestinal wall there was no increase in 5-FITrelease.When intestinal segments hacl been treated with cocaine (10 g/ml) or hexamethonium(TO ?/ml)m the increase in 5-TIT release caused by the stretching of the intestinal wallwas not affectccd the rate of its increase by the cocaine arxd hexarnethoniurn treatrraentwas calculated to be 1.4 and 2.6, respectively.The results thus obtained suggest that the increase in 5-HT released frorrn theintestinal wall may be more closely related to the stretching of the intestinal wall thanthe role of the nervous system. In the experiment rnentiomted above, the intestinal wallwas subjected to higher pressure and stronger stretching thtrn those for the physiologicalintestinal movements so that the effects of pressure and stretching might be magrrifiedon the release of 5-IHT frorm the nntestinal wall. Under tTtese conditions, the intestinalmovement never appeared. Therefor"e, it was assurned that the 5-HT release rnightresult in no intestinal motility, but stimulate the existing intestixaal motility.
