Quantitative study of apoptosis in normal rat gastroduodenal mucosa

The occurrence of apoptosis in the normal gastrointestinal mucosa has been given little consideration until now, although the phenomenon may be of interest in the light of recent hypotheses about its role in physiological cell renewal. In the present study, a quantitative evaluation conducted on normal gastric and duodenal mucosa of young rats has shown that apoptosis is a rare but constant phenomenon: 1.4 +/- 1.1 (mean +/- 1 s.d.) apoptotic bodies were observed within the surface epithelium of single gastric pits and 3 +/- 1 in duodenal villi. In both situations, the apoptosis showed a preferential localization in the juxtaluminal segments of the epithelium. This phenomenon appears distinct from passive exfoliation of mucosal cells and, as an expression of 'programmed cell death', it is likely to contribute to the normal intestinal epithelial cell turnover.     

Correlation between transmucosal potential difference and morphological damage during aspirin injury of gastric mucosa in rats

The potential difference (PD) that is maintained across healthy gastric mucosa is thought to be due to asymmetric ion pumping combined with resistance to back-diffusion of the separated charge. However, the structures that are responsible for this have not been clearly defined. This study examined the temporal changes in PD in rat stomach after injury by a single dose of aspirin. Multiple linear regression was used to compare this with the time course of several parameters of histological damage: (i) the per cent mucosal length showing superficial (confined to surface and gastric pits), deep (involving the isthmus or deeper in oxyntic glands) and total damage; (ii) the number of discrete erosions; and (iii) the total area of erosions per cm sectioned. Mucosal PD fell during the first 30–60 min after aspirin. Superficial damage appeared early and was already recovering by this time. The time course of deep damage more closely matched the alterations in PD and stepwise regression analysis showed that this could be predicted by the amount of deep damage alone (P < 0.001). Changes in transmucosal PD after acute aspirin injury probably reflect damage to structures in the oxyntic glands and not just the breaking of the surface and pit cell ‘barrier’.     

Role of mucosal blood flow in duodenal ulcer formation induced by dulcerozine

To clarify the role of mucosal blood flow in the pathogenesis of ulcer formation, the authors investigated dulcerozine-induced duodenal ulcers in rats. Administration of dulcerozine, 500 mg/kg by intragastric route or 250 mg/kg given intraperitoneally, induced acute ulcers in the duodenum, but not the stomach, in all rats. Using the pyloric ligation method, it was determined that although dulcerozine significantly increased gastric acid secretion, no duodenal ulcers were observed in these animals. The administration of 1 ml of 0.1 N HC1 every hour for 6 hours did not induce duodenal ulceration. The mucus glycoprotein content of the corpus, antrum and proximal duodenum did not differ following dulcerozine administration. Duodenal mucosal blood flow, which was measured by an electrolytically generated hydrogen gas clearance technique, decreased significantly following dulcerozine administration even in pylorus-ligated rats. In contrast, there was an increase in the gastric mucosal blood flow following administration of the drug. Therefore, not only an increase in gastric acid secretion but also a decrease in duodenal mucosal blood flow are suggested to be responsible for dulcerozine-induced duodenal ulceration.     

Effects of electroacupuncture on gastric mucosal blood flow and transmucosal potential difference in stress rats

ＥｆｅｃｔｓｏｆｅｌｅｃｔｒｏａｃｕｐｕｎｃｔｕｒｅｏｎｇａｓｔｒｉｃｍｕｃｏｓａｌｂｌｏｏｄｆｌｏｗａｎｄｔｒａｎｓｍｕｃｏｓａｌｐｏｔｅｎｔｉａｌｄｉｆｅｒｅｎｃｅｉｎｓｔｒｅｓｓｒａｔｓＸＵＧｕａｎＳｕｎ１，ＳＵＮＹｏｎｇ１，ＷＡＮＧＺｈｅ...     

胃溃疡大鼠胃粘膜血流量与泌酸变化的研究

用手术将十二指肠内容物持续胃内反流制成大鼠胃溃疡及经转流后的溃疡愈合模型进行研究。结果表明,溃疡组于胃窦小弯侧可见8.84±3.08(m~2)~(-3)的慢性溃疡形成,并显示胃粘膜血流量降低,G细胞密度、壁细胞数增加。溃疡愈合组经转流后大部分溃疡已愈合,G细胞密度、壁细胞数降低,粘膜血流量增加。本实验提示,泌酸细胞增多,泌酸量增加和胃粘膜缺血可能是溃疡形成的重要因素,增加胃粘膜的血液供应,降低胃酸分泌可促进溃疡愈合。     

pH profile of esophagus in patients with inlet patch of heterotopic gastric mucosa after tetragastrin stimulation

In a series of 1771 endoscopic examinations from 1988 to 1990, we observed 62 cases (3.3%) of inlet patch of heterotopic gastric mucosa (IPHGM) in the upper esophagus. Ten of the IPHGM patients complained of throat discomfort or globus sensation, and these symptoms were relieved by histamine H₂-antagonists, suggesting that these symptoms could be caused by acid secretion from IPHGM. Acidity under tetragastrin stimulation was measured in the esophagus and compared with the pool of gastric juice and saliva under direct vision by a newly devised endoscopic method. Congo red staining was also carried out after pH measurement. Significant pH reduction at IPHGM was observed in three cases, and black coloration with Congo red staining in the IPHGM was observed in four cases. These findings suggest that IPHGM is a mucosal change with latent acid secretion.     

Effects of intestinal mucosal blood flow and motility on intestinal mucosa

AIM:To investigate the role of intestinal mucosal blood flow(IMBF) and motility in the damage of intestinal mucosal barrier in rats with traumatic brain injury.METHODS:Sixty-four healthy male Wistar rats were divided randomly into two groups:traumatic brain injury(TBI) group(n = 32),rats with traumatic brain injury;and control group(n = 32),rats with sham-operation.Each group was divided into four subgroups(n = 8) as 6,12,24 and 48 h after operation.Intestinal motility was measured by the propulsion ratio o...     

New method of evaluating gastric mucosal blood flow by ultrasound

Objective. Evaluation of gastrointestinal blood flow is important. However, a non-invasive measurement method has not yet been established. The aim of this study was to compare measurement of normal gastric mucosal blood flow by advanced dynamic flow (ADF) flash echo imaging (FEI) with intravenous Levovist with measurement by laser Doppler flowmetry (LDF) to clarify the usefulness of ADF-FEI and thereby consider its feasibility as a non-invasive gastric mucosal blood flow measurement method. Material and methods. Measurements were obtained in 25 beagle dogs (8-month-old males, body-weight, 10.6±1.3 kg, mean±SD). After insertion of a gastrointestinal endoscope, gastric mucosal blood flow at the greater curvature of the corpus was measured by LDF, and images of gastric mucosal blood flow were obtained by ADF-FEI (frequency; 4.7 MHz) with intravenous injection of Levovist (30 mg/kg). ADF-FEI images were transferred to a personal computer. A region of interest was set on the mucosa of the greater curvature of the corpus, and a time intensity curve (TIC) was plotted from the measured echo intensities. The area under the curve (AUC) calculated from the TIC and the median flow determined by LDF were analyzed and compared. Results. Evaluation of normal gastric mucosal blood flow by ADF-FEI was possible in all animals. There was a strong, significant correlation between gastric mucosal blood flow measured by LDF and the AUC obtained by ADF-FEI (r=0.869, p<0.0001). Conclusions. Gastric mucosal blood flow can be accurately measured by ADF-FEI with intravenous Levovist injection.     

Real-time visualization and quantitation of canine gastric mucosal blood flow by contrast-enhanced ultrasonography

Objective. Contrast-enhanced ultrasonography has become a method of choice for evaluating gastric blood flow, but intermittent scanning techniques can sometimes distort the results. Low-mechanical index imaging using Definity as the injected contrast material has been advocated for real-time evaluation of microperfusion in other organs. We investigated the reliability of low-mechanical index imaging using Definity in the evaluation of gastric mucosal blood flow. Material and methods. Under general anesthesia, 10 beagle dogs weighing 9–10 kg underwent real-time harmonic imaging under low acoustic power (mechanical index?=?0.2) after intravenous contrast injection using Definity (60 mg/kg). Laser Doppler flow measurement was also performed to evaluate gastric mucosal blood flow. After administration of a diclofenac sodium suppository, low-mechanical index imaging and laser Doppler flowmetry were repeated. Results. Real-time visualization of gastric mucosal blood flow was successful in all dogs undergoing low-mechanical index imaging with Definity. Quantitative assessment of gastric mucosal blood flow was successful in eight dogs. After diclofenac sodium administration, gastric mucosal blood flow measured by both laser Doppler flowmetry and contrast ultrasonography decreased in seven of eight dogs; in the other dog, gastric mucosal blood flow increased slightly. A strong positive correlation was evident between blood flow measured by laser Doppler flowmetry and low-mechanical index imaging (r=0.777, p<0.005). Conclusions. Low-mechanical index imaging with Definity is a non-invasive way to evaluate gastric mucosal blood flow in real-time, high-resolutional images, which may have additional important gastrointestinal tract applications.     

Effect of lafutidine,a histamine H2-receptor antagonist,on gastric mucosal blood flow and duodenal HCO3- secretion in rats: relation to capsaicin-sensitive afferent neurons

Lafutidine is a new type of antiulcer drug, possessing both an antisecretory effect, exerted via a blockade of the histamine H₂ receptor, and gastroprotective activity, mediated by capsaicin-sensitive afferent nerves (CSN). In the present study, we examined the effect of lafutidine on gastric mucosal blood flow (GMBF) and duodenal HCO₃ ^– secretion (DAS) under basal and acid-stimulated conditions in rats. Under urethane anesthesia, GMBF was measured using a laser Doppler flowmeter in a chambered stomach before and after exposure to 20 mM taurocholate (TC) plus 50 mM HCl, while DAS was measured in a proximal duodenal loop before and after mucosal acidification (10 mM HCl for 10 min) by titrating the perfusate at pH 7.0 using a pH-stat method and by adding 10 mM HCl. Lafutidine given intraperitoneally affected neither GMBF nor DAS under basal conditions, but augmented an increase in both GMBF and DAS induced by mucosal acidification. Although the acid-induced GMBF and DAS responses were significantly mitigated by both indomethacin and sensory deafferentation but not by ruthenium red (RT), the vanilloid receptor (VR)-1 antagonist, the responses were preserved in lafutidine-treated animals, even in the presence of indomethacin. Both GMBF and DAS were significantly increased by local application of capsaicin, the responses being attenuated by indomethacin and RT as well as sensory deafferentation. Lafutidine augmented the GMBF and DAS responses to capsaicin and preserved the responses, even in the presence of indomethacin. Capsaicin evoked an increase in [Ca²⁺]_i in rat VR1-transfected HEK293 cells, while lafutidine had no effect by itself on [Ca²⁺]_i in these cells and did not affect the increase in [Ca²⁺]_i evoked by capsaicin. In conclusion, these results suggest that lafutidine mimics endogenous effects of prostaglandins to augment the GMBF and DAS responses to acid or capsaicin, probably by sensitizing CSN through an unknown site other than VR1. The luminal H⁺ itself is not a ligand for the RT-sensitive site of VR1 but plays a modulator role in the CSN-mediated physiological responses.     

Sucralfate protection against ethanol-induced injury of rat gastric mucosa in vitro and in vivo

A number of mechanisms for sucralfate protection of gastric mucosa during ulcer healing and protection from experimental injury have been proposed. One currently held postulate that sucralfate acts by inhibiting acid/pepsin attack and creating, at acid pH, a barrier to diffusion of hydrogen ions was tested. The experiments took advantage of a cultured rat antral mucosal model in which ethanol injury is assessed by release of radiolabel from ⁵¹chromiumloaded mucosa. In this model, with mucosa cultured in the absence of pepsin activity at a neutral pH, sucralfate conferred marked protection; specific ⁵¹chromium release fell from 12.4% (s.e.m. = 0.7) in controls to 8.9% (s.e.m. = 0.9) at 0.5 mg/ml (P < 0.05) and 3.4% (s.e.m. = 0.5) at 2.0 mg/ml (P < 0.001) of sucralfate and was abolished at 10 mg/ml and 40 mg/ml (P < 0.001). Pretreatment with sucralfate in vivo also protected the mucosa against subsequent ethanol challenge in the cultured mucosal model, control 12.3% (s.e.m. = 1.9) versus sucralfate pretreatment 6.9% (s.e.m. = 0.7) (P < 0.02). Using computer-assisted macroscopic assessment of mucosal damage after ethanol dosage by gavage, it was further demonstrated that sucralfate protection in vivo is dose-dependent and prolonged, lasting for at least 5 h at a dose of 200 mg/kg. It is concluded that sucralfate-induced protection of the gastric mucosa is long-lasting and can occur via mechanisms other than minimization of acid/peptic attack.     

Effects of Weitongling decoction on gastric mucosal blood flow and modelsof Spleen deficiency syndrome in rats

AIM To study the protective effects of Weitongling decoction (WTL) on gastric mucosa.METHODS Rats with gastric lesion induced by dehydrated alcohol were used to observe the gastric mucosalblood flow (GMBF), rats with spleen deficiency syndrome induced by reserpine were applied to investigatethe D-xylose absorption rate, the Alcian blue binding properties of gastric wall, the gastric acid secretion andthe activity of pepsin.RESULTS Remarkable increases in GMBF (19.5±3.5 mL/min, 20.4±3.3 mL/min respectively in largedose group and small dose group, P<0.01), in Alcian blue binding properties of gastric wall (2.497 mg±0.138 mg, 2.223 ug±0.186 mg respectively in large dose group and small dose group, P<0.05) and in D-xylose absorption rate (1.287±0.043, 1.294±0.019 respectively in large dose group and small dose group,P<0.05) were found after administrations of WTL, while no significant alteration in gastric secretion wasshown and in vitro WTL did not neutralize gastric acid.CONCLUSION WTL can improve the Spleen deficiency syndrome, strengthen the gastric mucosal barrier,and thus protect gastric mucosa against injury agents.     

Role of capsaicin-sensitive afferent neurons in mucosal blood flow response of rat stomach induced by mild irritants

The role of capsaicin-sensitive sensory nerves in gastric mucosal blood flow (GMBF) responses to mild irritants was investigated in the rat stomach mounted on a lucite chamber using hypertonic NaCl and 0.2 N HCl. Exposure of the mucosa to hypertonic NaCl (0.5, 0.75, 1 M) for 10 min caused a reduction in the transmucosal potential difference (PD) in a concentration-related manner, followed by an increase of luminal pH and GMBF. In contrast, mucosal application of 0.2 N HCl caused no or little change in PD and pH, but increased GMBF significantly. Functional ablation of capsaicin-sensitive sensory nerves significantly inhibited the increase of GMBF after exposure to these irritants, although the PD and pH responses induced by 1 M NaCl remained unaltered by this treatment. Pretreatment with indomethacin (5 mg/kg, subcutaneously) significantly attenuated the GMBF responses to 1 M NaCl and 0.2 N HCl and inhibited the increase of pH caused by 1 M NaCl. Mucosal application of capsaicin (0.1 mg/ml for 10 min) produced an increase of GMBF without being accompanied by change in PH and pH, and this effect was significantly blocked by either indomethacin or chemical deafferentation. These results suggest that capsaicin-sensitive sensory nerves as well as endogenous prostaglandins may be involved in the mechanism of GMBF responses induced by mild irritants, and the latter might sensitize these nerves to mucosal irritation. PD reduction may be obligatory for pH but not GMBF responses.     

Epalrestat prevents the decrease in gastric mucosal blood flow and protects the gastric mucosa in streptozotocin diabetic rats

We have recently reported that steady-state gastric mucosal blood flow (GMBF) is decreased in streptozotocin (STZ) diabetic rats, and that their GMBF response to burn-stress is impaired, probably via a nitric oxide (NO)-mediated mechanism. Accordingly, this study was designed to investigate the relation of aldose reductase (AR) and NO synthase to the regulation of GMBF during chronic hyperglycemia. STZ rats were treated with or without chronic oral administration of an AR inhibitor, epalrestat (EPA) and/or an NO synthase inhibitor, N-nitro-L-arginine methyl ester (L-NAME). GMBF was measured by laser-Doppler velocimetry (LDV). In the STZ rats, GMBF after a 24-h fasting period was decreased significantly 4 weeks after the onset of diabetes and this was accompanied by an increase in the gastric ulcer index (UI) (a measure of the length of gastric erosions and ulcers). Chronic oral administration of EPA to the STZ rats dose-dependently inhibited the increased UI and the decreased GMBF after the fasting stress, whereas chronic oral administration of L-NAME further increased the UI and further decreased the GMBF. EPA administered in combination with L-NAME to the STZ rats reduced the effects of L-NAME, but the effects did not reach significance. These results suggest that EPA protects the gastric mucosa of diabetic rats, by preventing the decrease in GMBF that is, at least in part, caused by NO-related mechanisms. (Received Mar. 3, 1998; accepted Aug. 28, 1998)     

电针对狗胃粘膜血流量的影响及与血浆胃肠激素的关系

目的观察电针对狗胃粘膜血流量、血浆胃肠激素水平的影响及两者间变化的关系，以探讨电针对胃粘膜保护作用机制．方法将２０条狗随机分为４组，即：空白对照组，非经非穴组，上巨虚组，足三里组（每组５条）．采用激光多普勒血流仪测定狗胃粘膜血流量．用ＲＩＡ法同步测定血浆促胃液素（ＧＴ），生长抑素（ＳＳ），内皮素（ＥＴ）含量，用生化法测定一氧化氮（ＮＯ）含量，分析其电针前后的变化，并观察变化规律．结果电针后足三里组胃粘膜血流量显著升高（Ｖ，４６±０７→６９±１１，Ｐ＜００１），其他组无显著变化．电针后足三里组血浆ＧＴ，ＮＯ含量也显著升高（ｎｇ／Ｌ，６５±１２→１０２±２１，Ｐ＜００１），而ＳＳ，ＥＴ含量显著下降（ｎｇ／Ｌ，２３１±１８→１９４±２７，Ｐ＜００５；９７８±１７９→５５８±１５３，Ｐ＜００５）；上巨虚组ＮＯ含量显著上升，ＥＴ显著下降（Ｐ＜００５），但足三里组的变化趋势更明显．空白对照组，非经非穴组则无显著变化．结论电针足三里穴可使狗胃粘膜血流量增加，与通过影响胃粘膜血流量的某些活性物质的含量改变有关，并具有一定的穴位特异性．     

Induction and intracellular localization of a 72-kDa heat shock protein in rat gastric mucosa after water-immersion stress

We investigated the expression and changes in the intracellular localization of a 72-kDa heat shock protein (HSP72) in rat gastric pyloric and fundic mucosa before and after water-immersion stress. Severe mucosal damage was found in the fundic mucosal area of the stomach after this stress. However, no mucosal lesion developed in the pyloric mucosal area. HSP72 in both the soluble and insoluble fractions of the pyloric and the fundic mucosal areas was significantly increased after water-immersion stress, peaking 6 h after the initiation of the stress. The increase in HSP72 was more significant in the pyloric mucosal area than in the fundic mucosal area under both normal and stress conditions. The increase of HSP72 in the pyloric mucosal cells occurred prior to the formation of the mucosal lesions, whereas the increase of HSP72 in the fundic mucosal cells was observed after ulcer formation. An immunohistochemical study showed that HSP72 was constitutively expressed in the cytoplasm of the gastric mucosal cells, and that the intranuclear induction of HSP72 was remarkably intense in the pyloric mucosal cells, especially in the proliferative zone, compared with the fundic mucosal cells. Our results may suggest that HSP72 has an important cytoprotective function in gastric mucosal cells and that there is a “biophysical” difference between pyloric and the fundic mucosal cells.     

An experimental study of gastric mucosal blood flow in endotoxemia of the rat,with special reference to the vagus nerve and EDRF

Gastric mucosal lesions are an important complication in endotoxemia. In order to define the role played by the vagus nerve and endothelial-derived relaxing factor (EDRF) in gastric mucosal blood flow, an investigation was carried out on four groups of rats: a control group; a group given lipopolysaccharide (LPS, 5 mg/kg); a group given gossypol-acetic acid (gossypol), which has an injurious effect on the vascular endothelial cell; and a group given L-NG-monomethyl arginine (LNMMA). Following the administration of acetylcholine and papaverine hydrochloride (via the splenic artery) and vagus nerve stimulation in all four groups of rats, the effects of vagus nerve stimulation and EDRF on the gastric mucosal blood flow were determined with a laser Doppler rheometer. In the LPS group, the gastric mucosal blood flow was decreased after acetylcholine administration and vagus nerve stimulation. This was also the case in the gossypol group. These findings suggest that inhibition of EDRF release may be responsible for the reduced gastric mucosal blood flow observed in endotoxemia.     

Monochloramine impairs mucosal blood flow response and healing of gastric lesions in rats: relation to capsaicin-sensitive sensory neurons

AIMS:We examined the effects of monochloramine (NH2Cl) on the gastric mucosal blood flow (GMBF) response and the healing of ethanol-induced gastric lesions in rats. METHODS: Rats fasted for 18 h were given the 99% ethanol p.o. for induction of gastric lesions, and were fed normally from 1 h later onwards. Monochloramine, at non-ulcerogenic doses (5 to approximately 20 mmol/L), was given p.o. twice daily for 7 days, starting 2 h after ethanol treatment. RESULTS: Gastric lesions caused by ethanol healed almost completely within 7 days with re-epithelialization. The repeated administration of NH2Cl significantly delayed the healing of ethanol-induced gastric lesions in a dose-dependent manner. The damaged mucosa showed a marked rise in H+ permeability, resulting in luminal acid loss, but this process was accompanied by an increase of mucosal blood flow. Monochloramine did not affect the increased mucosal H+ permeability observed in the stomach after damage by ethanol, but significantly inhibited the mucosal hyperemic response associated with luminal acid loss. Prior exposure of the mucosa to NH2Cl (20 mmol/L) did not affect the gastric hyperemic response caused by mucosal application of misoprostol (a prostaglandin E1 derivative) or NOR-3 (a nitric oxide donor), but totally attenuated the increase of GMBF in response to intragastric capsaicin. Impaired healing and GMBF responses were also observed in rats following chemical ablation of capsaicin-sensitive sensory neurons. CONCLUSIONS: These results suggest that NH2Cl impaired the healing of acute gastric mucosal lesions at low concentrations, and this action may be attributable, at least partly, to the impairment of gastric hyperemic response caused by the dysfunction of capsaicin-sensitive sensory neurons.     

Mechanism by which histamine increases gastric mucosal blood flow in the rat

The mechanism by which histamine increases gastric mucosal blood flow (GMBF) was investigated in the anesthetized rat. The experiment was performed in the presence of tripelennamine, an H₁ antagonist, to focus on the relationship between acid secretion (H₂-receptor-mediated response) and GMBF. The stomach was mounted on a Lucite chamber, perfused with saline, and GMBF was measured by laser Doppler flowmetry simultaneously with acid secretion. Under these conditions, histamine at the submaximal dose significantly increased GMBF as well as acid secretion, and this increase of GMBF was completely blocked when acid secretion was inhibited by cimetidine or omeprazole. The elevation of GMBF caused by histamine was also significantly attenuated when luminal H⁺ was removed by intraluminal perfusion with NaHCO₃ or glycine. Glycine by itself did not affect the increase of acid secretion induced by histamine and the increase of GMBF caused by isoproterenol, yet significantly inhibited the GMBF response induced by pentagastrin. Intraluminal perfusion with HCl also produced an increase of GMBF in a concentration-related manner, even in the presence of omeprazole during histamine infusion. Pretreatment of the animals with indomethacin significantly blocked the GMBF responses induced by either histamine or luminal HCl. These results suggest that the increase of GMBF during acid secretion induced by histamine may be caused by luminal H⁺ and involve endogenous prostaglandins in its mechanism.