Subject(s)
Decompression Sickness/diagnosis , Ultrasonography , Animals , Dogs , Humans , Models, Biological , Venae CavaeABSTRACT
1. The electrical activity of the small intestine of conscious dogs, rabbits and sheep was recorded by means of chronically implanted electrodes and was related to mechanical changes in the bowel.2. A pattern of activity characteristic of segmental contractions (a prolonged series of bursts of spike activity superimposed on the basic electrical rhythm) was recorded successively at consecutive sites along the small intestine. This activity was as pronounced in the rabbits and sheep which were fed ad lib. as in the dogs which were fasted for 12 hr.3. The segmental contractions began in the duodenum and had a frequency of 15-20/24 hr. As they passed along the intestine, their velocity diminished and in the rabbits and sheep this was associated with an increased duration of activity. Most of the contractions reached the terminal ileum taking 1.5-2 hr in each of the species despite the differences in the length of the small intestine.4. The propagation of segmental contractions appears to be a normal and common activity of the intact bowel and it may have a propulsive as well as a mixing function.
Subject(s)
Gastrointestinal Motility , Intestine, Small/physiology , Muscle Contraction , Action Potentials , Animals , Dogs , Duodenum/physiology , Electrodes, Implanted , Ileum/physiology , Jejunum/physiology , Muscle, Smooth/physiology , Rabbits , Sheep , Time FactorsABSTRACT
The electrical potentials were recorded from the antrum, the duodenum, the ileum and the first part of the colon of ponies under (a) normal resting conditions, (b) during nonpainful colic and (c) after intravenous morphine administration. The normal pony, at rest, had five contractions of the antrum per minute. On the small intestine, the basal electrical activity decreased from the duodenum (14-15/min) to the ileum (10-11/min). The small bowel also had three types of motility: peristaltic waves, rhythmic segmentations and random contractions. On the colon, bursts of potentials indicating intense motor activity occurred at the rate of 20 to 30 per hour. Morphine given intravenously (IV) greatly increased the frequency of the electrical potentials of the antrum and the longitudinal bands of the colon. During non-painful colic, hyperactivity of the cranial small intestine was continuous. Spasms of the jejunum occurred every minute and could not be relieved by morphine (IV). When colic was painful, jejunal spasms announced the crisis of intense abdominal pain. After morphine (IV) the spasms and pain disappeared; the jejunum remained hyperactive, the motility of the colon was increased while the antrum became quiet.