Frequency Of Gastric Contractions Research Articles

Effect of tetramethylpyrazine on reserpine-induced gastric lesion in rats.

The present study was undertaken to determine the effect of tetramethylpyrazine administered intraperitoneally on gastric lesions, gastric acid secretion, gastric barrier mucus secretion, and gastric contraction in reserpine-treated rats. The results of this study demonstrated that tetramethylpyrazine at doses of 0.5, 1, 10, and 20 mg/kg significantly inhibited the formation of gastric lesions induced by reserpine, with suppressive rates of 57.5%, 64.0%, 94.1%, and 96.0%, respectively. Tetramethylpyrazine (1 and 20 mg/kg) significantly prompted the secretion of gastric barrier mucus but had no effect on the secretion of gastric acid. Our findings also showed that tetramethylpyrazine (1 and 20 mg/kg) significantly suppressed the frequency of gastric contractions, but had no effect on the amplitude of gastric contraction. These results indicate that the protection of tetramethylpyrazine results, in part, from promoting gastric barrier mucus secretion and suppressing the frequency of gastric contraction, but not from suppressing the secretion of gastric acid and the amplitude of gastric contraction.

Scintigraphic test of gastric emptying and motility: preliminary results in patients with chronic gastritis

To record gastric peristalsis using a conventional scintigraphic gastric emptying test the frame rate was increased to 1 frame per 3 s at 10, 30, and 50 min postprandially. The gastric contraction frequency was obtained from the first harmonic of a Fourier transform of a gastric region of interest (ROI) curve. The propagation of gastric contractions was better revealed from computed functional images of the phase and amplitude distribution as compared with the multiple scintigraphic images. The maximal count-rate changes per pixel were calculated as an estimate of the most prominent regional contractile activity of the gastric wall. Among 12 patients with chronic gastritis the group with more severe dyspeptic complaints (n = 6) had significantly higher count-rate changes per pixel when compared with the group with minor complaints (20.0, 21.1 and 14.2 vs 12.9, 12.0, and 10.4 counts/pixel × s at 10, 30, and 50 min, respectively; p < 0.05). The mean half-times of gastric emptying (61, SD 11 vs 54, SD 13 min) and the mean gastric contraction frequencies (2.99, SD 0.19; 3.09, SD 0.33; 3.07, SD 0.10 vs 3.15, SD 0.15; 3.17, SD 0.13; 3.23, SD 0.20 cycles/min at 10, 30, and 50 min, respectively) did not show significant differences between both groups. Our preliminary results agree with the hypothesis of the occurrence of more powerful, nonexpulsive gastric-wall contractions in patients with more severe dyspeptic complaints. Hence, additional quantification of gastric motility allowed a more detailed evaluation of gastric-motor-activity disorders that were for so long not accessible to conventional gastric-emptying tests.

Response of the Human Gastrointestinal Tract to Erythromycin

Erythromycin has been shown to increase gastrointestinal motility in dogs when given in large doses, whereas small doses of the antibiotic elicit a premature migrating motor complex (MMC) in both dogs and humans. To study the effects of therapeutic doses of erythromycin in humans, erythromycin was given to 14 human volunteers either intravenously, 7 mg (kg · 30 min), or orally (500 mg) and pressure recordings were made from perfused or solid state catheters. Migrating motor complexes were counted before and after erythromycin administration. Intravenously administered erythromycin caused a large increase in the amplitude, duration, and frequency of gastric contractions whereas the small bowel appeared to be inhibited. No MMC was observed after the onset of the intravenous infusion. After oral administration of erythromycin the number of MMC increased significantly. Erythromycin caused side effects in 71% of subjects. In conclusion, at therapeutic doses erythromycin causes a disturbance of human upper gastrointestinal motility and can prove a useful tool in motility studies.

Effect of denervation on initiation and coordination of gastroduodenal motility in turkeys.

The effect of total extrinsic denervation of the stomach on the rhythmicity and coordination of the gastroduodenal cycle was determined in domestic turkeys. The vagus and two gastric branches of the sympathetic nerve were sectioned at the level of the glandular stomach. Motilities of the glandular stomach, proximal duodenum, and caudal thin muscle of the muscular stomach were monitored via implanted strain gauge transducers for 1 h every other day. Denervation had no significant effect on initiation of contractions or frequency of gastric contractions in fed birds, but fasted birds whose stomachs were extrinsically denervated exhibited significantly slower contractions than controls. In addition, denervation uncoupled the coordination of the duodenal and gastric contractions in the gastroduodenal cycle. Moreover, birds with extrinsically denervated stomachs exhibited a cephalic phase of gastric motility that was significantly delayed in onset compared with controls. These results suggest the existence of both a neural and endocrine component in the avian gastric response to the sight of food. Extrinsic input seems to be an important modulator of gastric motility in birds and is essential for the normal coordination of the gastroduodenal contraction cycle.

Hemorrhage with blood reinfusion and the relationship between gastroduodenal motility and bile reflux in rats.

The relationship between gastroduodenal motility and bile reflux was studied in normal rats and in rats subjected to hemorrhage and blood reinfusion. Bile secretion decreased from 5.3 +/- 0.4 to 4.1 +/- 0.5 microL/(min.100 g rat) (p less than 0.05) during the hypovolemic stress and recovered after blood reinfusion. Gastric bile salt content was low (0.1 +/- 0.03 mumol/(h.100 g rat] during control period and hemorrhage but increased to 0.7 +/- 0.12 mumol/(h.100 g rat) (p less than 0.001) during the 3 h following blood replacement. Marked gastric and duodenal retention of polyethylene glycol was observed immediately after hypovolemia with the former being evident even after 3 h following blood reinfusion, while duodenal emptying recovered rapidly after reinfusion. The frequency of gastric contraction remained unchanged during hemorrhage but decreased after 90 min following blood replacement, whereas the frequency of duodenal contraction abruptly decreased during hemorrhage and recovered after reinfusion. Both gastric and duodenal contractile pressure was significantly decreased during hemorrhage. After reinfusion, the former remained suppressed while the latter was fully recovered within 1 h. Thus, a significant duodenogastric bile reflux observed after reinfusion was due to a higher duodenal contractile pressure, and the uncoordinated gastroduodenal motility with the duodenal motility fully recovered soon after reinfusion while that of the stomach remained suppressed.

Effects of cold-restraint stress on gastric ulceration and motility in rats

The effects of stress by restraint at 4°C for 2 hr and of drug treatment on gastric lesion formation and motor activities (contraction frequency, amplitude and tone) were studied in rats. Restraint at room temperature (22°C) produced a small ulcer index in the controls and did not significantly affect gastric motor activities; atropine and verapamil reduced but bethanechol increased gastric contractions under the same experimental conditions. Restraint at 4°C markedly elevated the ulcer index. The frequency of gastric contractions was significantly increased in the first hr but the amplitude was depressed during the whole 2-hr observation period. Gastric tone initially fell but rose in the second hr of cold-restraint stress. Atropine and verapamil pretreatment prevented stress-induced ulcer formation and suppressed the frequency and amplitude of gastric contraction. Bethanechol stimulated both frequency and amplitude without significantly influencing stress ulcer size. It is unlikely that gastric hypermotility plays a major role in stress ulceration; the stomach smooth muscle-relaxing action of atropine and verapamil may contribute only partly to their antiulcer effects.

Effects of Diet Temperature on Tolerance of Enteral Feedings

Nasogastric tube feedings administered at three temperatures were studied for effect on gastric motility, total gastrointestinal transit time, diarrhea, and subjective sensations in normal volunteers. Following a period of base-line observation, six volunteers received tube feedings at one of three temperatures: cold (8-11 degrees C), room (23-26 degrees C), or warm (36-39 degrees C). There was no significant difference between the temperature of the feeding and gastric motility patterns in selected postfeeding periods. Administration of diets at all three temperatures resulted in a similar decrease in the frequency of gastric contraction and similar patterns of return of gastric activity. After cold feedings two subjects experienced cramping accompanied by diarrhea. No gastrointestinal disturbances were reported following warmer infusions.

The gastric motility patterns induced by direct and reflex excitation of the vagus nerves in the anaesthetized ferret.

1. Under urethane anaesthesia the ferret has a stomach which exhibited spontaneous contractions. The amplitude of the contractions was reduced, but never abolished, by vagotomy, atropine or hexamethonium. 2. Electrical stimulation of the cut peripheral end of the cervical or abdominal vagus nerves activated both excitatory and inhibitory fibres, whereas reflex activation by stomach distension or by cytoglucopenia was predominantly excitatory on gastric motility. The magnitude of the response to electrical stimulation was dependent upon the stimulus frequency, duration and voltage. Stimulation for periods longer than 10 sec at 10 Hz caused an increase in tone and motility which declined almost to control values if it was sufficiently prolonged. 3. Short duration stimulation, 10 sec or less, at 10 Hz produced a single gastric contraction. An identical response could only be produced if a period of rest from 30 to 120 sec separated two such stimuli. 4. The frequency of gastric contractions was independent of the frequency of nerve stimulation. 5. Using a divided stomach, vagal non-cholinergic, non-adrenergic fibres were shown to cause mainly relaxation of the corpus region. Similar fibres supplied the antrum and their activation caused inhibition of spontaneous contractions. The transmitter may be 'purinergic' as rebound contractions were observed.

Inhibition of Gastric Motility by Duodenal Contents in Turkeys

Twenty young turkeys were prepared with two fistulas in the duodenum, one at the flexure and a second in the distal duodenum. Pressures were measured and recorded in the glandular and muscular stomachs and in the duodenal flexure by means of open-tipped polyethylene tubes connected to pressure transducers. Several stimuli were applied to the mucosa of the distal duodenum while recording. Corn oil, mineral oil, hypertonic and isotonic solutions, and dilute HCl were injected, and balloons were inflated, within the distal duodenum. Inhibition of gastric motility was evident within seconds after injection of 4 to 10 ml. of 0.1N HCl and 6 to 12 ml. of 1600 mOsM NaCl solutions or after balloon inflation. Within minutes after an injection of 6–12 ml. of corn oil the frequency of gastric contractions was slowed. Mineral oil (10 ml.) did not inhibit motility. Sufficiently large quantities of neutral isotonic saline (>30 ml.) slightly depressed normal gastric motility. Recorded pressure changes characteristic of intestinal refluxes were observed frequently during most of the responses to these stimuli. It is hypothesized that the inhibition of gastric motility which occurs within seconds after application of an intraduodenal stimulus may be the result of a neural mechanism while that caused by the injection of corn oil may be humorally mediated.