I Aizawa's research while affiliated with Gunma University and other places

Publications (49)

Chapter
Vomiting, which seems to be a protective function against ingested noxious materials, is one of the major pathophysiological phenomena in the gut. Gastrointestinal motility associated with vomiting had been studied with using contrast media in the stomach or duodenum (1), or electrodes on the intestine (2). However, mechanical movements during vomi...
Article
Contractile activity in the gallbladder was measured by means of chronically implanted force transducers in conscious dogs. Intravenous infusion of motilin (0.3-0.9 μg/kg.h) induced transient contractions during the interdigestive but not during the digestive period. The contractions of the gallbladder occurred simultaneously with the initiation of...
Article
To study possible physiologic relationships between somatostatin and the gastric interdigestive contractions (GIC), gastric motor activity, and plasma somatostatin-like immunoreactivity (SLI) concentration were determined simultaneously in four conscious dogs, each of which was studied on two separate occasions. Plasma SLI level was highest during...
Article
The hypothesis that extrinsic innervation of the small bowel provides pathways for initiation and coordinated propagation of the interdigestive migrating contractions (IMC) was reinvestigated in dogs. Motor activity was measured by chronically implanted force transducers. After a control study, 40-cm segments of the jejunum were extrinsically dener...
Article
Effect of dopamine and its antagonists, domperidone and metoclopramide (MCP), on contractile activity of the lower esophageal sphincter (LES) and the stomach was studied in 5 healthy conscious dogs. Contractile activity was measured by means of chronically implanted force transducers. Contractile activity of the LES and the stomach was completely i...
Article
Extraluminal force transducers were chronically implanted onto the serosal surface of the gastrointestinal tract in dogs and the interdigestive migrating contractions (IMC) were studied in conscious dogs. When the IMC occurring periodically in the stomach reaches the distal ileum, the next IMC develops in the stomach. We therefore studied the effec...
Article
Continuous measurements of intraduodenal pH changes were made in five healthy conscious dogs by means of a miniature pH electrode inserted into the duodenum through a chronically implanted duodenal cannula. Gastric motor activity was also recorded simultaneously by means of a chronically implanted force transducer. When dogs were fed once a day wit...
Article
We have previously reported that during the interdigestive state repeated episodes of high-amplitude contractions interrupted by long-lasting motor quiescence were seen to occur regularly until the next meal in the dog. However, none of the dogs used in our laboratory showed such regular changes in gastric motor pattern all the time during the inte...
Article
Extraluminal force transducers were chronically implanted onto the serosal surface of the gastrointestinal tract in dogs and the interdigestive migrating contractions (IMC) were studied in conscious dogs. When the IMC occurring periodically in the stomach reaches the distal ileum, the next IMC develops in the stomach. We therefore studied the effec...
Article
Extract of pueraria root is one of the most popular but the most important crude drugs which has been long used in both China and Japan. However, pharmacological and physiological studies of pueraria root have not been carried out. Recently, Miura et al. successfully extracted and purified a factor from pueraria root to stimulate smooth muscle cont...
Article
Simultaneous measurement of plasma motilin concentration and gastrointestinal contractile activity was make in 12 healthy dogs. Plasma motilin concentration was measured by radioimmunoassay and gastrointestinal contractile activity was monitored by means of chronically implanted force transducers. During the interdigestive state, it was found that...
Article
The effect of synthetic motilin on contractile activity in the lower esophageal sphincter (LES) and the stomach has been studied in 5 healthy dogs by means of chronically implanted strain gage force transducers. Motilin produced strong contractions in the LES and the stomach simultaneously after intravenous doses ranging from 0.3 to 2.7 microgram/k...
Article
Simultaneous measurements of motor activity in the lower esophageal sphincter (LES) and the stomach were recorded continuously for several weeks by means of chronically implanted force transducers in five conscious dogs. We found that the LES contracted precisely in association with the gastric body during the interdigestive state. During this time...
Article
Gastrointestinal contractile actiivity from the gastric body to the terminal ileum in conscious dogs was continuously recorded for several weeks by means of chronically implanted strain-gage force transducers. It was found that the 24-hr changes in the gastrointestinal contractile activity consisted of the two different major patterns, the digestiv...
Article
Since 1975, when motilin was synthesized in Japan1,2, we concentrated our efforts on various aspects of motilin in man and dog. We have found that: 1.) motilin induces the cyclic recurring episodes of caudad-moving bands of strong contractions that move from the lower esophageal sphincter (LES) to the terminal ileum, 2.) motilin has no significant...
Chapter
Recently it has been reported that motilin increases lower oesophageal sphincter (LES) pressure1,2, but the physiological significance of its effect on the LES has not been elucidated. A perfused catheter method has generally been used to measure LES pressure; however, this method is not suitable for long-term measurement on conscious animals. To a...
Article
Changes in lower esophageal sphincter (LES) motility have been mainly studied by intraluminal manometry. However, it is not suitable for continuous measurement of LES pressure. With extraluminal force transducers developed and constracted in our laboratory, we measured changes in contractile activity of the LES. Three anesthetized mongrel dogs were...
Article
Changes in lower esophageal sphincter (LES) motility have been mainly studied by intraluminal manometry. However, it is not suitable for continuous measurement of LES pressure. With extraluminal force transducers developed and constracted in our laboratory, we measured changes in contractile activity of the LES.Three anesthetized mongrel dogs were...
Article
Simultaneous measurements of plasma motilin concentration and contractile activity were made in 7 healthy conscious dogs. Plasma motilin concentration was measured by radioimmunoassay and gastric contractile activity was recorded by means of chronically implanted force transducers. When gastric contractile activity was in the interdigestive state,...
Article
The interaction between motilin, pentagastrin and feeding was investigated during the interdigestive gastric motor state in 4 healthy conscious dogs. We confirmed previous reports that an i.v. infusion of synthetic motilin always induced a pattern precisely like that of the naturally-occurring interdigestive contractions of the stomach. Pentagastri...
Article
Gastric movements were monitored in five conscious dogs weighing 9 to 13 kg by extraluminal force transducers (EFTs) which were independently developed and constructed in our own laboratory. After chronically implanting EFTs both in the canine gastric body and antrum we succeeded in making continuous recordings of their movements over several days....
Article
Gastric movements were monitored in five conscious dogs weighing 9 to 13 kg by extraluminal force transducers (EFTs) which were independently developed and constructed in our own laboratory. After chronically implanting EFTs both in the canine gastric body and antrum we succeeded in making continuous recordings of their movements over several days....
Article
Twenty-four-hour changes in gastric motor activity were recorded in 4 healthy adult dogs in the conscious state by means of extraluminal force transducers. Three major different gastric motor activity patterns were recognized during 24 hr: digestive, intermediate, and interdigestive. The digestive pattern was characterized by steady low-amplitude c...
Article
The effect of intravenous infusion of synthetic motilin on gastric motor activity was investigated by means of chronically implanted force transducers in 4 conscious dogs. Since the gastric motor pattern consisted of two major subpatterns, digestive and interdigestive motor activity, motilin was tested for its motor stimulating activity in both sta...
Article
Effect of synthetic motilin on gastric motor activity was investigated in conscious dogsfor the purpose of studying physiological action of this new gastrointestinal polypeptide bymeans of chronically implanted extraluminal strain gage force transducers. It was found that gastric motor activity was divided into two major patterns; digestiveand inte...
Article
An extraluminal strain-gauge force transducer has been developed for recording contractile activity of the gastrointestinal smooth muscle. The details of its construction and implantation were described. The transducer unit allows for continuous long-term recordings (more the 5 months) from conscious experimental animals. It could be constructed in...
Article
Twenty-four-hour changes in gastric motor activity were recorded in 4 healthy adult dogs in the conscious state by means of extraluminal force transducers. Three major different gastric motor activity patterns were recognized during 24 hr: digestive, intermediate, and interdigestive. The digestive pattern was characterized by steady low-amplitude c...
Article
The interaction between motilin, pentagastrin and feeding was investigated during the interdigestive gastric motor state in 4 healthy conscious dogs. We confirmed previous reports that an i.v. infusion of synthetic motilin always induced a pattern precisely like that of the naturally-occurring interdigestive contractions of the stomach. Pentagastri...
Article
Gastric motor activity was monitered by means of extraluminal force transducers by strain gauge in conscious dogs. Extraluminal force transducers were sutured onto the serosal surface of the gastric body and the antrum. We observed a diurnal rhythm of gastric motility and this rhythm was divided into the fed state and the fasting state including th...
Article
In the gastro-enteric endocrine cells, polypeptide hormones (or prohormones) are stored in the secretory granules, presumably being connected with compound proteins of larger molecules. These polypeptides and proteins are produced in the rough ER-Golgi system. The granules further contain amines such as 5HT and catecholamines. Radioautographic stud...
Article
Gastrointestinal contractile activity from the lower esophageal sphincter to the terminal ileum in the conscious dogs was continuously recorded on a multi-channel polygraph for several weeks by means of chronically implanted strain gage force transducers. It was found that the 24-hour gastrointestinal motor activity consisted of the two different m...
Article
As reported previously, gastrin-stimulated gastric secretion in the dog and in man was suppressed by an intravenous infusion of secretin, These results, both in the dog and in man, also were obtained by introduction of acid into the duodenum, which indicated that both endogenous and exogenous secretion inhibit gastrin-stimulated gastric secretion a...

Citations

... Vomiting is associated with a series of gastrointestinal motor events 1 which act to propel intestinal contents orad for subsequent expulsion and the primary motor event which propels intestinal contents into the stomach 2,3 is the retrograde giant contraction (RGC). The RGC begins just prior to vomiting in mid small intestine 4,5 and it travels orad to the gastric corpus. 1,5 Cervical vagotomy blocks activation of the RGC throughout the digestive tract 5 , and transection of the celiac branch of the vagus nerve blocks activation the RGC 6 in the small intestine only, therefore, the RGC is initiated by the central nervous system (CNS) through the vagus nerves, and propagation through the small intestine is dependent upon a neural pathway through the celiac ganglia. ...
... described powerful fasting gastric contractions that were closely associated with 'hunger pangs'. 7 Almost 40 years ago, it has been hypothesised that these 'hunger contractions' correspond to phase III contractions, which are part of MMC, 8 but this has never been formally studied. MMC is subdivided into three phases, of which phase III is the most characteristic one, with a burst of contractions originating from the antrum or small intestine and migrating distally. ...
... The unifying concept of an increased secretion and motility of the stomach as an immediate response to the sight or taste of food was dealt an important blow by the finding that in man (Carlson, 1912) feeding inhibited rather than enhanced the gastric motility. Lorber, Komarov & Shay (1950) reported similar results in dogs with oesophagostomy, although the presence in the vagi ofinhibitory as well as stimulatory fibres suggests that the over-all response could be an increased activity of the antrum (Boiselle et al. 1971) counteracted by body relaxation (Itoh, Aizawa, Takeuchi & Takayanagi, 1977). This study confirmed that the access to food in the fasted rat is always accompanied by an early and significant increase in antral motility as previously described, as well as the concomitant quiescence of the fundus (Pascaud et al. 1978). ...
... Phase III, known as the migrating motor complex (MMC), consists of forceful peristaltic waves that originate simultaneously in the stomach and the duodenum and propagate along the entire length of the small intestine. The main function of the MMC is to empty the stomach and small intestine from chyme residues, mucous, and bacteria [5][6][7]. As the MMC activity reaches the small intestine, the velocity of propagation of the peristaltic waves declines from the proximal jejunum to the distal small intestine, which is most likely related to a decreased number of motilin receptors along the gastrointestinal tract [5]. ...
... The latter finding made us doubt that the antiserum had a nonspecific effect on gastrointestinal motility because motilin is considered to be physiologically involved only in the regulation of interdigestive motor activities, and not in the digestive state. 1 In fact, when sodium azide itself was given at the dose contained in 1.0 mL of the antiserum, it abolished gastrointestinal contractions both in the digestive and the interdigestive periods. ...
... The jugular catheter was exteriorized via a skin incision on the neck and was xed to the adjacent skin with silk sutures. After the abdominal cavity was opened via a middle incision, force transducers [52,53] were implanted onto the serosal surfaces of the fornix, gastric body, gastric antrum, midduodenum, and jejunums 1 and 2 (20 and 40 cm distal to the Treitz's fascia, respectively) to detect circular muscle contraction. ...
... These results suggest that some biochemical processes, such as enzymatic reactions, might be involved in the motilin-induced potentiation and that its site of action might be the muscarinic receptor and/or associated G proteins. cation channel; gut smooth muscle; migrating motor complex MOTILIN HAS BEEN IMPLICATED as a gut peptide hormone in initiating an intermittent migrating motor complex in the fasting gut (14,27). This has been supported by the observation that the plasma motilin levels fluctuate in synchrony with the interdigestive migrating motor complex, but stay depressed during a postprandial period, and that intravenous administration of motilin or several erythromycin derivatives that are motilin agonists can induce a similar motor complex (10). ...
... 5 As another example of its potential integrating effects, motilin-induced contractions in the lower oesophageal sphincter are well coordinated with tonic contractions in the gastric fundus and body in humans and dogs. 2,6 In the fasting state, colonic motor activity is also stimulated dose-dependently in dogs. 7 However, much less is known about the effects of motilin after a meal, especially in the lower bowel. ...
... The dogs were fasted overnight before each experiment. After the interdigestive motor complex [35] had been recorded at the antrum, ≥ 2-h of contractile activity was recorded. Test material or vehicle (5 mL of 154 mmol/L NaCl solution) alone was then administered as an intravenous bolus injection during a quiescent state of the whole colon in the interdigestive state. ...
... GAS was from G cells of pyloric antrum for gastric acid secretion, and we found that GAS levels were not changed under systemic hypoxia for six days. MTL has been identified in the blood of dogs by means of radioimmunoassay [22], with function of stimulating pepsin output and enhancing activity of the stomach [23]. We found that MTL levels were not influenced by systemic hypoxia for six days in rats. ...