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Biomedical subjects

Y Ruckebusch

Publications and source records attributed to Y Ruckebusch.

At least 127 records · Page 7Linked to original sources
PubMed1978

Postoperative intestinal motility in dogs and sheep.

Electrical activity of the small intestine was recorded from chronically implanted electrodes in dogs and sheep. The effects of laparotomy and surgical procedures were identified under general anesthesia. Laparotomy induced in both species a complete inhibition of electrical spiking activity during the stage of muscular and peritoneal incision. The inhibitory period due to laparotomy was shorter in dogs than in sheep and in both species less marked at the duodenal level. A secondary period of inhibition (ileus) lasting from 6 hr for a resection of the colon to 24 hr for a transection of the small bowel was observed in dogs after a transient phase of normal activity during 3-6 hr. The period of inhibition due to abdominal surgery lasted from 48 to 72 hr and occurred at the time of surgery in sheep. In both species, inhibition due to laparotomy and surgical procedures was prevented by splanchnicectomy. The results showed that myoelectric activity of the different parts of the small intestine is specifically inhibited and/or disorganized through peripheral reflex pathways. They are activated at different degrees by laparotomy and abdominal surgery.

Abdomen↗
PubMed1978

Effects of anesthesia and surgical procedures on intestinal myoelectric activity in rats.

Electrical spiking activity of the duodenum and jejunum was recorded from chronically implanted electrodes in rats during volatile or barbiturate anesthesia and following laparotomy. The normal pattern of electrical spiking activity in the fasted rat, with myoelectric complexes at 15-min intervals, was transiently replaced by quiescence during ethyl ether anesthesia. A slight increase in irregular spiking activity occurred after induction with pentobarbital, and the only effect of thiopental anesthesia was a reduction in the velocity of propagation of the complexes by 20%. Under barbiturate anesthesia, incision of the skin did not inhibit myoelectric activity, but incision of each abdominal muscle layer had an immediate and transient inhibitory effect; the deeper the layer, the longer was the inhibition. Peritoneal incision consistently produced inhibition of spiking activity which was prolonged by exposure of the bowel to air and intestine handling. The inhibitory effects produced by surgery persisted after vagotomy or transection of the spinal cord at the thoracic level but disappeared after splanchnicectomy. The above results suggest that a somatovegetative reflex with efferent pathways in the splanchnic nerves is involved in the first stage of operative inhibition of intestinal myoelectric complexes.

Abdomen↗
PubMed1978

A basic relationship between gastric and duodenal motilities in chickens.

Chickens were chronically fitted with a duodenal cannula and pairs of electrodes implanted in the wall of the muscular stomach, duodenum and ileum. Smooth muscle electrical activity was recorded in both fed and fasted conditions under a 12--12 h dark-light schedule. Two major patterns of activity were identified. The first consisted of spike bursts that propagated rapidly either aborally from the stomach or orally from the ileum. Aborad-propagated spike bursts were most frequent during the daytime; this circadian variation was abolished by vagotomy, which also increased the frequency of orad-propagated spike bursts. The second pattern was characterized by periods of repetitive spike bursts lasting 3--10 min and spreading aborally at a slower rate. In the fasted chicken, the daily frequency was increased and the period of repetitive spike bursts resembled the prolonged bursts of spike potentials recorded in the feline small intestine. The results suggest that the propulsion of digesta might depend on the ratio of spike bursts moving aborally from the stomach to those moving orally from the ileum. Both factors were influenced by the level of stomach activity.

Action Potentials↗
PubMed1978

[Transmural potential and a profile of intestinal motility in dogs].

Relationships between motor patterns of the jejunum and transmural potential changes were studied in the dog chronically fitted with transparietal electrodes and with an intraluminal catheter. The transmural potential increases above 13 mV at the beginning of the irregular spiking activity of a myoelectric complex and reaches 6 mV at the end of a phase of regular spiking activity. Oscillations of 3 mV are recorded during the phases of irregular spiking activity. A sustained increase of the potential occurred after feeding : 10 mV for a diet rich in protides and fat, 25 mV when glucides are predominant.

Animals↗
PubMed1978

[Central origin on the excito-motric action of morphine on intestine].

In ewew fitted with a cerebro-ventricular cannula and equipped with extra-cellular bipolar electrodes on the antrum and proximal small intestine, an intraventricular injection of morphine at a dose (40 micrograms/kg) ineffective peripherally was followed within 1 min by an increased spike activity of the duodenum without disruption of the occurrence of migrating myoelectric complexes. This effect was paralleled by a reduction of antral motility and abolished by small intraventricular doses of nalorphine. After an intravenous injection of large doses of the drug drug (0.8 mg/kg), spike activity was increased at both jejunal and duodenal level without changes in the antrum and followed by a long-lasting disorganization of the motor profile. The results suggested a centrally mediated gastro-duodenal effect of morphine.

Animals↗
PubMed1978

On the control of caecal motility in sheep.

The electrical activity of the terminal ileum and of the caecum was recorded continuously from chronically implanted electrodes in 8 ewes fed on hay ad libitum. The caecum even as an isolated pouch showed a cyclic activity closely linked tho the frequency of myoelectric complexes on the terminal ileum. This phenomenon disappeared in the absence of myoelectric complexes. The distention of an isolated caecal pouch induced local changes in the electrical activity with disappearance of the cyclic activity. It is concluded that two factors are involved in the control of caecal motility, one originating at the distal ileum and the other related to the endoluminal pressure.

Animals↗
PubMed1977

Origin of migrating myoelectric complex in sheep.

The electrical activity of the gastroduodenal junction was recorded in conscious sheep for 8 to 12 wk with chronically implanted electrodes. The flow of digesta was simultaneously recorded, and the duodenal bulb was isolated at the time of implantation. The mean slow-wave frequency of the antrum was 5.6 +/- 0.3/min with spike bursts randomly superimposed on about 60% of the slow waves. The activity of the duodenal bulb was characterized by an absence of slow-wave unpropagated spike bursts and by two types of propagated spike bursts. The first consisted of isolated bursts accompanied by a rapid movement of digesta through the entire duodenum and proximal jejunum. The second, an irregular series of 8-12 spike bursts was associated with total evacuation of the duodenal bulb, followed in turn by an inhibition of antral spiking activity and the development of a migrating myoelectric complex (MMC) in the distal duodenum. The results indicate that in sheep organization of the MMC is located at the duodenal level where the duodenal bulb has a reservoir function.

Animals↗
PubMed1977

Migrating myoelectrical complex of the small intestine. An intrinsic activity mediated by the vagus.

In healthy conscious parenterally fed dogs and in sheep on their usual diet, the basic motor profile on the small intestine consists of recurring cycles of action potential activity. This cyclic pattern called the migrating myoelectrical complex comprises two distinct phases termed irregular, and regular spiking activity and is followed by a period of quiescence. The pattern persists after bilateral transthoracic vagotomy and in animals rendered diabetic by alloxan. In dogs, feeding disrupts the migrating myoelectrical complex pattern by obliterating the phases of regular spiking activity and quiescence for 6 to 12 hr, depending upon the amount of dry matter intake. After vagotomy a latency in the disruption of the migrating myoelectrical complex pattern with feeding occurs and in vagotomized dogs rendered diabetic, the duration of disruption is strongly reduced. In sheep, the duration of irregular spiking activity of a jejunal segment increased or decreased corresponding to the bulk of digesta, a phenomenon damped after vagotomy. The results indicate that the role of the vagus is limited to (1) prompting prandial disruption, which is then maintained by hormonal effect; (2) regulating the irregular spiking activity duration in relation to the bulk of digesta.

Action Potentials↗
PubMed1977

Mechanisms of propulsion in the small intestine.

In sheep like in rats 2 hr after feeding and in fasting dogs, the rate of passage of digesta along the small intestine is related to the migration of the myo-electric complexes (MMCs). The modifications of this basic common pattern and that of its two consecutive irregular and regular phases were related to changes in the flow of digesta in both the proximal and distal parts of the small intestine. A high flow rate in the jejunum is associated to an increase in duration of the phases of ISA and by supernumerary MMCs at this level. Normally at the ileal level, the flow of digesta was lower than in upper parts with an increase in retention time associated both with a slow migration of the complexes and the disappearance of about one third of them after traversing 60% of the length of the small bowel. These experiments suggest that the origin, propagation and frequency of the basic MMC pattern as well as the ratio of ISA to quiescence are operative factors involved in small intestine propulsive activity. The continuous spiking activity seen immediately after feeding in rats and dogs and the autonomous pattern of activity of the ileum during prolonged fasting in sheep represent extreme changes of the basic MMC pattern.

Action Potentials↗
PubMed1976

The Fusus coli of the rabbit as a pacemaker area.

Section of the rabbit's proximal colon orad to the fusus coli resulted in a marked reduction in both slow-wave frequency and differentiation of the two kinds of faeces produced. This indicates the existence of a pacemaker area and a mechanical role for the reversed oral-aboral gradient of the proximal colon.

Action Potentials↗
PubMed1976

[Perinatal evolution of the sleep cycles in the lamb].

The alternation between NREM-REM sleep occurs in the foetal lamb as an ultradian rhythm with a period of 30-40 min. until 6 to 8 hrs. before birth. Cycling of sleep-wakefulness in the neonate is related to a circadian cycle of exploratory activity and feeding, to an ultradian basic rest activity cycle and to an alternation between NREM-REM within a period of sleep.

Animals↗
PubMed1976

Sleep patterns of the laboratory cat.

The effects of feeding schedule and external stimuli on sleep patterns were investigated in cats fed to maintain their mean body weight. The ECoG, EOG and EMG wer recorded from 3 male cats fed once daily and under a 12:12 light--dark schedule. The results for 15 working days were compared with those obtained at week-ends and under continuous lighting, fasting, reduced food intake or overfeeding. Feeding was also divided into 3 meals per day. Despite some differences in their responsiveness. All cats exhibited the usual values for the critical variables of SWS: diurnal placement, intermittency and total amount. A low percentage of PS per 24 h was recorded. This was related both to the restricted amount of food eaten and to the feeding schedule. Reduced external stimuli at week-ends resulted in concentration of sleep during daytime, whereas sleep was reduced during continuous lighting in conjunction with an increased percentage of drowsinessess. The most marked effect of fasting (pig fat) was fragmentation of sleep episodes. Divided meals and an increased food intake both increased the total sleep duration. It is suggested that the restricted amount of food and relatively enriched environment used, accompanied by a reduced sleep duration, may be comparable to that seen in free animals. Sleep patterns in the cat are very responsive to light--dark schedule, reduced external stimuli and fasting.

Animals↗