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Biomedical subjects

M Schemann

Publications and source records attributed to M Schemann.

98 records · Page 6Linked to original sources
PubMed1986

Mechanical characteristics of phase II and phase III of the interdigestive migrating motor complex in dogs.

In conscious dogs certain parameters of the jejunal interdigestive phase II and phase III activity were studied by means of closely spaced strain gauges and videofluoroscopy. During phase III the frequency, force, and rise time of contractions and the contraction spread were increased, whereas the intercontractile intervals and the propagation velocity of contractions were diminished in comparison to phase II. The contraction waves of phase III were variable with regard to their length of spread and their rate of caudad migration. These two parameters adjusted the duration, the propagation velocity, and the length of the activity front. Propagation of contractions was sometimes interrupted by periods of uncoupling. Propagation velocities within contraction waves varied according to the pattern slow-fast-slow-fast, producing the videofluoroscopically observed roller coaster movements of the luminal contents. It is concluded that phase II and phase III are characterized not only by the occurrence of irregular and regular activity but by a significant change of a number of contraction parameters.

Animals↗
PubMed1986

Postprandial patterns of canine jejunal motility and transit of luminal content.

The effects of different nutrient meals and a noncaloric viscous cellulose meal (control) on the motor activity of the canine jejunum were studied. Contraction patterns were detected through six closely spaced, strain-gauge transducers and were analyzed by a computer. Luminal transit was assessed videofluoroscopically. Control meals moved rapidly (1.9 cm/s) along the jejunum. This was achieved by contractions that occurred at a high frequency (12.8 cpm) and propagated over long distances (9.9 cm). In contrast, the transit rates of the nutrient meals were considerably slower (0.5-1.0 cm/s), the frequency of contractions (5.0-8.9 cpm) and the length of spread of contraction waves (2.6-4.8 cm) were decreased, and the incidence of stationary contractions occurring individually or in clusters was increased. A mathematical model incorporating frequency of contractions and the length of their propagation was used to predict the transit of jejunal contents. The results of correlation tests and of the mathematical model revealed that the length of spread of contraction waves was the most important factor that influenced transit.

Animals↗
PubMed1986

5-Hydroxytryptophan and cisapride stimulate propulsive jejunal motility and transit of chyme in dogs.

We investigated in conscious dogs the effects of intravenously administered 5-hydroxytryptophan (5-HTP) and cisapride on the postprandial jejunal mechanical activity by means of six closely spaced extraluminal strain gauge transducers. Drugs were given after administration of a nutrient meal. 5-HTP was given additionally after the administration of a noncaloric cellulose meal. Computer assistance was used to determine the temporal and spatial relationship of contractions and thereby to evaluate the length of spread of contractile waves. Both substances increased the propulsive activity, the contractile force and the motility index and fastened the transit rate of digesta. 5-HTP exhibited the most potent effect when given after administration of the nutrient meal.

5-Hydroxytryptophan↗
PubMed1986

Computer analysis of intestinal motility: effects of cholecystokinin and neurotensin on jejunal contraction patterns.

The motility of the intestine consists of various contractile patterns which have either segmenting or propulsive function. To differentiate and quantify intestinal contractile patterns the temporal and spatial relation of several closely spaced transducers have to be analysed. For this purpose a special computer method was developed. The system consists of a subsystem for data acquisition and on-line peak detection and a personal computer for data storage and off-line analysis. The subsystem identifies each contraction on the basis of preestablished threshold and timing criteria. Economical and appropriate processing of signals from multichannel recordings requires data reduction which is performed by storing only the voltage and time characteristics of the contraction minimum and maximum. Subsequent analysis of the stored data, especially the measurement of the length of spread of contractions yields a more detailed analysis than commonly obtained. This method enables a rapid detection and exact numerical analysis of signals independent of their wave shapes. Intravenous infusion of neurotensin after administration of a non-caloric cellulose meal decreased the length of spread of contraction waves and slowed the transit rate of luminal contents. Cholecystokinin had a powerful stimulating effect by increasing the length of spread of contraction waves and by accelerating the transit rate.

Animals↗
PubMed1985

Pharmacology of a gut motility stimulating enkephalin analogue.

The enkephalin analogue pentapeptide Hoe 825 (Tyr-D-Lys-Gly-Phe-L-homocysteine-thiolactone) is a mixed mu/delta opiate agonist. The peptide stimulated interdigestive gut motility at all parts of the intestine in conscious and anaesthetized animals. In dogs digestive motility, measuring mechanical activity, was stimulated with respect to segmental and propulsive properties. The canine uterus was sensitive to the enkephalin. Hoe 825 acts by i.v. or s.c. application, whereas the latter increases the duration of action significantly. The compound's effect can be blocked by naloxone indicating a receptor mediated action, which is localised peripherally. The compound is devoid of a dependence risk, because it does not penetrate into the CNS. At therapeutic doses (in the dog 0.5-2 micrograms/kg i.v.) the compound does not affect cardiovascular, renal or endocrine functions and was without effect on serum blood glucose levels in rats and rabbits.

Action Potentials↗
PubMed1984

Mechanical factors regulating gastric emptying of viscous nutrient meals in dogs.

The aim of this study was to determine the mechanisms controlling gastric emptying of viscous meals. In four conscious dogs the antral, pyloric and duodenal activities were recorded with strain-gauge transducers and induction coils during gastric evacuation of an inert cellulose meal and of four nutrient meals containing mannitol, casein, glucose or oleic acid. Gastric emptying and the internal pyloric and duodenal diameters were measured from radiographs. The nutrients delayed gastric emptying and diminished to a various extent the antral and duodenal motility as well as the pyloric opening. The motility gradient between antral and duodenal activity showed no relationship to the emptying delay. The duodenal lumen was reduced and the propulsive contractions of the duodenum decreased while the segmental activity increased. The findings suggest that gastric emptying is controlled by (1) the depth of the antral waves, (2) the pyloric opening, (3) the receptive relaxation of the duodenum and (4) the type of the duodenal contractions. By contrast the sequence of the terminal antral contraction and the pyloric closure, as well as the co-ordination between pyloric and duodenal contractions, played no important role in regulating gastric emptying.

Animals↗
PubMed1982

The utility of cellulose meals for studies on gastrointestinal motility in dogs.

This study evaluated the effect of a cellulose meal and a cellulose-oleic acid meal on gastroduodenal motility and gastric emptying. The cellulose meal produced a high antral motility index (100 +/- 34 V/10 min) and a high proportion (80.2%) of propulsive duodenal contractions. The oleic acid meal was associated with a significantly lower antral motility index (70 +/- 34 V/10 min), a high proportion (78.7%) of segmental duodenal contractions, and a reduced emptying rate (half time 93 +/- 18 versus 30 +/- 7 min). Results indicate that the inert cellulose meal is advantageous in studying the effects of different nutrients on gastrointestinal motility.

Animals↗