Search PubMed⌕ Search

Biomedical subjects

M Papasova

Publications and source records attributed to M Papasova.

69 records · Page 4Linked to original sources
PubMed1978

Character of the spike activity on both sides of duodenal transection depending on the regeneration of the intrinsic nervous system.

Experiments are carried out on dogs with transection of the duodenum followed by end-to-end anastomosis and chronically implanted silver ball-shaped electrodes on the muscle wall of the stomach and on the segments of the duodenum proximal and distal to the transection. Dissociation of the spike activity of the two duodenal segments is established after the operation. As early as the second week after the transection, parallel with this single group of spike potentials propagating through the anastomosis are also observed. With increasing the time interval from the operation propagation of the spike activity along the length of the muscle occurs more and more frequently. The difference in the percentage of spike activity of the two duodenal segments is greatest during the first and second months after the operation. At the beginning of the third month it decreases gradually to reach 10 per cent approximately during the fifth month after the operation. In preliminary vagotomized dogs the difference in the percentage of the spike activity is maintained around 20-30 per cent. In dogs with definitely separated segment of the duodenum this difference becomes great and there are no tendencies towards reduction even in the sixth month post operation. Histological studies of the material taken from the area of the anastomosis of animals at different post-transection periods, subjected to silver impregnation after the method of Bielschowsky-Gross, show regeneration of the severed nerve bundles of plexus myentericus Auerbachi. The restoration of the spreading of the spike activity along the length of the duodenum is associated with restoration of the nerve structures in the muscle wall of the duodenum.

Animals↗
PubMed1977

Increase in the intestinal slow-wave frequency below the transection through electrical stimulation.

Experiments are carried out on dogs with chronically implanted leading-off electrodes on both sides of the transection at the level of the proximal duodenum. A pair of stimulating electrodes are also implanted below the transection. Electrical stimulation with impulses synchronized with the slow waves generated by the segment proximal to the section (amplitude 3-7 V, delay 0.2 s and duration 0.5 s) as well as with periodic impulses (18-21 cpm, duration 0.2-0.5 s and amplitude 3-10 V) results in shortening of the period T of several slow waves from the distal segment. Subsequently the frequency of the slow waves from this segment approaches that of the proximal segment. The restoration of the slow-wave plateau at the beginning of the small intestine depends both on the amplitude and on the frequency of the stimulating impulses. On the background of antagonists of the cholinergic (atr. sulf. 200 microgram/kg) and of the adrenergic systems (propranolol 2 mg/kg and phentolamine 1 mg/kg), increasing the frequency of the slow waves of the segment which is distal to the section requires an increase in the amplitude of the stimulating impulses. The role of the intrinsic nervous system for the assimilation of the slow-wave rhythm from the distal segment by the proximal one is discussed.

Animals↗
PubMed1976

Disturbances in the electrical and contractile gastric activities after bilateral transthoracic vagotomy.

Experiments were made on four dogs with chronically implanted electrodes. Fistula according to Bassov was made in one of the animals, and in each of the remaining three - two semiconductor silicon tensotransducers were sewn to the gastric wall. Bilateral transthoracic vagotomy results in inco-ordination between the rhythm of slow potentials generation from the body and from the antrum of the stomach. Slow potentials and contractions with frequencies usual for the stomach are recorded from the body of the stomach, while in the antrum there appear from time to time bursts of slow potential groups with relatively high frequency. These groups are not followed by contractions of the stomach wall or by changes in the intragastric pressure. Bilateral transthoracic vagotomy leads to disturbances in the conduction of the slow potential generated in the proximal segments of the stomach, as well as to distrubances in the propagation of the peristaltic wave.

Action Potentials↗
PubMed1976

Coordination between the longitudinal and circular layers of the stomach during the excitator-contractile process.

The coordination between the longitudinal and circular layers of the stomach muscle is studied using strips of cat stomach cut along the longitudinal and circular axis of the stomach, preserving the connection between them. The longitudinal muscle layer plays a leading role both with respect to the bioelectrical and to the contractile activity of the stomach. Under the effect of acetylcholine (10-7) the delay time of the circular muscle layer is shortened compared with the longitudinal layer (from 2.44+/-0.17 to 0.8+/-0.7 s). Under the effect of Ba ions not only shortening of this time is observed, but also inversion of the process-the circular layer becomes leading with respect to the contractile process in some moments.

Animals↗
PubMed1976

Participation of bivalent ions in the acetylcholine-provoked gastric smooth-muscle phasis contractions.

Experiments were carried out on muscle strips from cat antrum. Acetylcholine added to Ca++ -free medium containing EDTA (10-5M) exerted no effect on the phasic contractions of the gastric smooth muscle. Ba++at low concentrations (0,1 to 0,5mM) replaced Ca++with respect to the acetylcholine effect. On the background of blocked cholinergic (atropine 10-5M) and adrenergic (phentolamine 10-5 M and propranolol 10-5M) structures Ba++ provoked slow potentials and cotractions with a frequency of 9 to 10 cpm. delta600 (10-5M) blocked the Ba++-induced myogenic electrical and contractile activities of the smooth muscle. The role of the cholinergic structures for synchronizing the electrical and contractile activities of the smooth muscle is considered.

Acetylcholine↗