Changes in small intestinal motility in acute physical stress--an experimental study.

The objectives of the present study were: 1) to describe the modifications in motility of the small intestine in response to situations of acute physical stress during fasting and post-prandial periods. 2) To analyse the possible involvement of the adrenergic and beta-endorphinergic systems in these modifications. For this we used a total of 60 dogs. The motility of the small intestine was recorded using electromyography techniques (monopolar electrodes) and manometric techniques (submucous microballoons). Plasma levels of beta-endorphin and catecholamines were determined before and after the stimulus. We show that physical stress applied in phases I or II of the fasting period induced a significant increase in the percentage of slow waves followed by the action potential for 1 minute in the three locations of the intestine studied (duodenum, angle of Treitz and proximal part of the jejunum), lasting from 8 to 12 minutes (p less than 0.001). When it is applied during the early post-prandial period it is responsible for a significant decrease in the percentage of slow waves followed by the action potential for 1 minute for a period of 6 to 11 minutes (p less than 0.001). The administration of adrenergic blockers prevents the effect of hypomotility caused by acute physical stress (p less than 0.001), whereas the administration of naloxone favors this hypomotility effect (p less than 0.001). Acute physical stress, on being applied during the late post-prandial period increases the percentage of slow waves followed by the action potential for 1 minute for a period of 8 minutes (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)