Publications by authors named "Yamasato T"

We evaluated the visceral adipose tissue accumulation in university students in Okayama prefecture, Japan. Fifty-eight Japanese university students (10 men and 48 women, age 18.4 +/- 0.

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The effects of subtotal-gastrectomy (gastrectomy) on the spontaneous motility and caerulein-induced relaxation of the sphincter of Oddi (SO) were investigated in the dog. The spontaneous motility and the response to caerulein of the SO were recorded using perfusion method. The basal perfusion pressure (5.

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1. The role played by the 5-HT3 receptor, a serotonin subtype receptor, in peristaltic reflexes was studied in dogs first given ketamine, then anaesthetized with urethane (1.0 g kg-1, I.

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The sympathetic innervation of the internal and sphincter (IAS) and its physiological role in maintaining sphincter tone were histochemically and mechanically studied in dogs anesthetized with pentobarbital sodium. Numerous catecholamine-fluorescent nerve fibers with varicosities were identified in the IAS of normal dogs. Such fibers were markedly reduced at one week and one month after resection of the hypogastric nerves (HGNs) or the lumbar colonic nerve (LCN), and disappeared after combined HGN and LCN resection.

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FOY induced a dose-dependent inhibitory response on the gallbladder, sphincter of Oddi and duodenum of normal and gastrectomized dogs, although it induced an excitatory response in some dogs. The inhibitory response was not reduced or terminated by pretreatment with atropine, guanethidine, hexamethonium or/and proglumide. The FOY-induced inhibitory response reversed to the excitatory response in the sphincter of Oddi and duodenum by pretreatment with tetrodotoxin, but not in the gallbladder.

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Effects of the mesenteric nerve stimulation (MNS) on the twitch contraction induced by field stimulation were investigated regarding the relationship between myenteric neurons and extrinsic cholinergic nerves in the guinea-pig mesenteric nerve-ileal preparation. The twitch contraction was inhibited after MNS. The inhibition of the twitch contraction after MNS was induced twice, just after MNS (1st inhibition) and 2-3 min later (2nd inhibition) (type I), or once, just after MNS (1st inhibition) (type II), in recovery course of twitch contraction for 6-8 min.

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Antroduodenal contractions were studied in rat preparations. Augmented duodenal contractions occurred spontaneously in coordination with antral contractions in normal and saline-pretreated preparations. The coordination did not occur when muscle layers and the myenteric plexus were transversely cut at the duodenum just anal to the gastroduodenal junction.

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Neural regulation of the motility between the haustra and taenia coli was studied in the isolated rabbit proximal colon. Four types of haustral and taenial preparations were used: the haustral strip without the taenia coli (type 1), the haustral strip including the taenia coli (type 2), the L-shaped (taenia-haustra) preparations for recording the haustral (circular) response to taenial stimulation (type 3) and the L-shaped (haustra-taenia) preparation for recording the taenial (longitudinal) response to haustral stimulation (type 4). Field electrical stimulation induced a contractile response in the haustra and taenia coli.

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The participation of the parasympathetic and sympathetic nerves in the canine gallbladder motility was examined. Efferent stimulation of the parasympathetic (vagus) and sympathetic (celiac) nerves caused contraction or inhibition of the neck, body and fundus of the gallbladder. The contractile response induced by vagus nerve stimulation was reduced by subthreshold efferent stimulation of the celiac nerve, while the inhibitory response was neither reduced nor enhanced by subthreshold efferent stimulation of the celiac nerve.

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Effects of stimulation of the vagus and sympathetic nerves on bile duct peristalses were studied in pigeons anesthetized with urethane. Vagus stimulation increased the frequency of peristalses. Atropine, hexamethonium and tetrodotoxin abolished this excitatory effect.

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Neurotensin induced dose-dependent contraction in the isolated gallbladder, bile duct and ampulla of guinea-pigs, which were usually reduced by atropine and tetrodotoxin. In all cases, the neurotensin-induced contraction of the gallbladder was reversed to relaxation by indomethacin after administration of atropine and tetrodotoxin. The neurotensin-induced contraction of bile duct and ampulla was reduced by indomethacin, atropine and tetrodotoxin, and was slightly enhanced in some experiments after guanethidine administration.

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Effects of afferent stimulation of the lingual nerve (LNAS) on gastrointestinal motility and the reflex pathways which mediate the response to LNAS were investigated in rats. LNAS induced excitatory, inhibitory or biphasic responses in the stomach, duodenum and proximal colon. These responses continued after bilateral vagotomy, but were abolished after additional bilateral splanchnicotomy or transection of the spinal cord between Th4 and Th5.

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Trimebutine at low concentrations (6 X 10(-9)-1.4 X 10(-8) M) slightly enhanced the twitch response of isolated guinea pig ileum induced by transmural stimulation. At high concentrations (2 X 10(-8)-2 X 10(-7) M), however, it inhibited the twitch response in a dose dependent manner.

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The actions of the enkephalinergic neurons in the myenteric plexus on the gastrointestinal motility were studied using the opiate antagonist naloxone in the guinea pig in vitro and in vivo. Naloxone increased or decreased spontaneous contractions of the isolated small intestine. Both responses were abolished by atropine.

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Effects of cisapride on the motility of the digestive tract in vivo in dogs and the guinea-pig intestine in vitro were studied. Cisapride (0.05-2.

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Effects of domperidone on gastric emptying and gastric, duodenal and gallbladder motility were investigated. Intravenous injection of domperidone 2 mg/kg produced an acceleration of gastric motility without increase in the tone while a marked increase in the amplitude of peristaltic waves with a slight decrease in frequency was observed. Domperidone also produced an acceleration of duodenal and gallbladder motility.

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Effects of Loperamide on the motility of the isolated intestine in guinea-pigs, puppies and rats were examined. The spontaneous contractions of the small intestine and colon in puppies were inhibited at relatively high concentration of the agent (10(-5) g/ml). The peristaltic reflex in the guinea-pig ileum was slightly inhibited at concentrations of 10(-8) to 10(-7) g/ml, and was completely abolished at 10(-6) g/ml.

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In anesthetized dogs, intravenous administration or intrajejunal infusion of Loperamide produced the excitatory effect of gastric, small and large bowel motilities accompanied with elevation of the muscle tone. The excitatory response was slightly suppressed by administration of atropine. Such effects were similar to those of morphine and methadone.

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The isolated bile duct preparations, which contain the duodenal circular muscle, and the proper bile duct muscle preparations in the dolphin (Stenella caeruleoalbus) were used and their longitudinal motilities were recorded by means of strain gauge transducer. 1. Raising the intraluminal pressure produced the augmentation of the motility of the bile duct preparation.

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