Gastric functions in portal hypertension. Role of endothelin

Gastric food retention at endoscopy is associated with severity of liver cirrhosis

BACKGROUND

Gastrointestinal symptoms are prevalent in patients with cirrhosis. Cirrhotic patients have a known predilection to delayed gastric emptying compared to those without cirrhosis. However, the contributing factors have not been fully elucidated. Retained gastric food on esophagogastroduodenoscopy (EGD) has been used as a surrogate marker for delayed gastric emptying with reasonably high specificity. Therefore, we hypothesize that the frequency of retained gastric food contents at EGD will be higher in a cirrhotic population compared to a control population without liver disease. Additionally, we hypothesize that increased frequency of gastric food contents will be associated with increased severity of cirrhosis.

AIM

To determine the relative frequency of delayed gastric emptying among cirrhotics as compared to non-cirrhotics and to identify associated factors.

METHODS

We performed a retrospective case-control study of cirrhotic subjects who underwent EGD at an academic medical center between 2000 and 2015. Three hundred sixty-four patients with confirmed cirrhosis, who underwent a total of 1044 EGDs for the indication of esophageal variceal screening or surveillance, were identified. During the same period, 519 control patients without liver disease, who underwent a total of 881 EGDs for the indication of anemia, were identified. The presence of retained food on EGD was used as a surrogate for delayed gastric emptying. The relative frequency of delayed gastric emptying among cirrhotics was compared to non-cirrhotics. Characteristics of patients with and without retained food on EGD were compared using univariable and multivariable logistic regression analysis to identify associated factors.

RESULTS

Overall, 40 (4.5%) patients had evidence of retained food on EGD. Cirrhotics were more likely to have retained food on EGD than non-cirrhotics (9.1% vs 1.4%, P < 0.001). Characteristics associated with retained food on univariable analysis included age less than 60 years (12.6% vs 5.2%, P = 0.015), opioid use (P = 0.004), Child-Pugh class C (24.1% Child-Pugh class C vs 6.4% Child-Pugh class A, P = 0.007), and lower platelet count (P = 0.027). On multivariate logistic regression analysis, in addition to the presence of cirrhosis (adjusted OR = 5.83; 95%CI: 2.32-14.7, P < 0.001), diabetes mellitus (types 1 and 2 combined) (OR = 2.34; 95%CI: 1.08-5.06, P = 0.031), opioid use (OR = 3.08; 95%CI: 1.29-7.34, P = 0.011), and Child-Pugh class C (OR = 4.29; 95%CI: 1.43-12.9, P = 0.01) were also associated with a higher likelihood of food retention on EGD.

CONCLUSION

Cirrhotics have a higher frequency of retained food at EGD than non-cirrhotics. Decompensated cirrhosis, defined by Child-Pugh class C, is associated with a higher likelihood of delayed gastric emptying.

The protective effect of endothelin receptor antagonists against surgically induced impairment of gastrointestinal motility in rats

Endothelin (ET) receptor antagonists: BQ-123 (ET_A), BQ-788 (ET_B), tezosentan (dual ET receptor antagonist) protect against the development of postoperative ileus (POI) evoked by ischemia-reperfusion (I/R). The current experiments explored whether ET antagonists prevent the occurrence of POI evoked by surgical gut manipulation. Intestinal transit was assessed by measuring the rate of dye migration subsequent to skin incision (SI), laparotomy (L), or laparotomy and surgical gut handling (L+M) in diethyl ether anaesthesized rats (E). Experimental animals were randomly sub-divided into two groups depending on the time of recovery following surgery: viz. either 2 or 24 h (early or late phase POI). E and SI did not affect the gastrointestinal (GI) transit. In contrast, L and L+M significantly reduced GI motility in comparison to untreated group (UN). Tezosentan (10 mg/kg), BQ-123 and BQ-788 (1 mg/kg) protected against development of L+M evoked inhibition of intestinal motility in the course of late phase, but not early phase POI. Furthermore, tezosentan alleviated the decrease in the contractile response of the longitudinal jejunal smooth muscle strips to carbachol in vitro induced by L+M. The serum ET(1–21) concentration was not increased in either the early or the late phase POI groups after surgery compared to control animals. This study indicates that delay in the intestinal transit in late phase of surgically induced POI involves an ET-dependent mechanism.

Delayed gastrointestinal transit in patients with hepatocellular carcinoma

BACKGROUND AND AIM

Disturbed gastrointestinal (GI) motility exists in cirrhotic patients; however, less is known about the character of GI transit in hepatocellular carcinoma (HCC) patients. It is interesting to study the GI transit in HCC patients and to explore the patient factors modulating GI transit.

METHODS

A non-invasive hydrogen breath test, which measured the orocecal transit time (OCTT), was used to study GI transit in 40 HCC patients, 20 cirrhotics and 40 age- and sex-matched healthy volunteers with normal bowel habits. Meanwhile, their clinical manifestations and various blood parameters, such as platelet count, prothrombin time, erythrocyte sedimentation rate etc. were collected. The plasma endothelin-1 and nitrate/nitrite levels were also measured.

RESULTS

The OCTT were delayed in HCC and cirrhotic patients compared with controls (116.3 +/- 7.8 and 104.5 +/- 10.6 vs 75.3 +/- 5.1 min, P < 0.05). Neither the severity of liver damage, presence of ascites, tumor size, portal hypertension, nor various blood parameters, such as nitrate/nitrite, endothelin-1, platelet count etc., had any influence on GI transit. Only serum alpha-fetoprotein levels exhibited a trend toward positive correlation with the OCTT (r = 0.271, P = 0.091).

CONCLUSIONS

Hepatocellular carcinoma patients have delayed GI transit. The confounding factor responsible for the disturbance of GI transit in HCC patients needs further exploration.

Gastric motility in patients with presinusoidal portal hypertension

OBJECTIVE

The aim of this study was to evaluate the consequences of portal hypertension (PH) for the motor functions of the human stomach.

METHODS

The PH model used was the hepatosplenic form of mansonic schistosomiasis, as this is a condition characterized by PH but with considerably preserved hepatocellular function. The study included 15 patients with PH and 25 healthy volunteers who served as controls. The adaptive relaxation of the stomach was studied in 12 patients with PH and in 10 controls by a manometric method during rapid insufflation (25-30 s) of 700 ml of air into the gastric fundus. The gastric emptying of a liquid solution (15 patients with PH and 20 controls) and of a solid-liquid meal (nine patients with PH and 12 controls) was determined by gamma scintigraphy. The thickness of the gastric antrum wall was measured by ultrasonography in 12 patients with PH and in 10 controls.

RESULTS

Patients with PH showed the following: 1) reduction of the adaptive relaxation of the stomach (p < 0.0001); 2) acceleration of gastric emptying of the test solution (T 1/2, p = 0.0316), which became particularly expressive 25, 30, 40, and 50 min after ingestion (p = 0.0181, 0.0215, 0.0181, and 0.0215, respectively); 3) no alteration in gastric emptying of the solid-liquid meal as judged by T 1/2 values (p = 0.9170) or lag-phase values (p = 0.7544); and 4) a conspicuous increase in gastric wall thickness as determined by antrum wall measurements (p = 0.0008).

CONCLUSIONS

The reduced gastric adaptive relaxation demonstrated in patients with PH and normal hepatocellular function leads us to consider this condition as a cause of diastolic dysfunction of the stomach. In this disease, the motor alteration may be explained as a consequence of the reduction of gastric wall compliance, probably resulting from edema and vascular ectasia, which were indirectly detected by the increase thickness of the gastric antrum wall. The discrete acceleration of liquid gastric may be also related to the reduced gastric wall compliance.

Nutritional problems in end-stage liver disease: contribution of impaired gastric emptying and ascites

GOALS

To evaluate gastric emptying before and after paracentesis in patients with cirrhosis.

BACKGROUND

Patients with ascites often report early satiety. The effect of paracentesis on gastric emptying has not been studied previously.

STUDY

Twelve patients who required therapeutic paracentesis were studied (mean age, 57 years; range, 47-69 years). Gastric emptying was performed with radionuclide scintigraphy. Satiety was evaluated with a visual analogue scale. Wilcoxon signed-rank tests were used for comparison between pre-and poststudies.

RESULTS

The causes of cirrhosis included alcohol (seven patients), a combination of alcohol and hepatitis C (two), chronic hepatitis C only (one), primary biliary cirrhosis (one), and cryptogenic (one). The median volume of ascitic fluid removed at paracentesis was 5,450 mL (range, 2,500-7,200 mL). Median 2-hour gastric emptying was 65.5% before paracentesis and 61.5% after ( p > 0.05). Median 4-hour gastric emptying was 92.5% before paracentesis and 96.5% after ( p > 0.05). Both satiety score and caloric intake were significantly improved after paracentesis ( p < 0.05).

CONCLUSIONS

Although satiety and calorie intake improve after large-volume paracentesis in patients with cirrhosis, these changes do not seem to correspond with improved gastric emptying. Therefore, other mechanisms most likely contribute to satiety.

Beneficial effects of glycocholic acid (GCA) on gut mucosal damage in bile duct ligated rats

In order to investigate the effect of bile acids on gastrointestinal inflammations, bile duct ligated rats (BDL) were treated with GCA (25 mM/ml, oral or colonic) or saline I h before ethanol challenge and twice daily for 3 days in the ileitis group, while GCA was given twice daily for 3 days in the colitis group. BDL reduced the macroscopic and microscopic damage scores in the ileitis group compared to sham operated group, while it had no significant effect on ulcer or colitis groups. However, GCA given in BDL group reduced the ulcer index and microscopic damage in colitis group compared to saline-treated groups, but had no effect in ileitis group. Both BDL and GCA administration in BDL group reduced ileitis- or colitis-induced elevations in MPO levels. GCA administration in BDL group inhibited gastric acid output and volume. Our results suggest that oral or colonic administration of primary bile acids may be useful for the treatment of gastrointestinal inflammations.

Anti-ulcerogenic properties of endothelin receptor antagonists in the rat

BACKGROUND

Endothelins have been implicated in gastric mucosal damage in a variety of animal models. Exogenous ET-1 and ET-3 are causally associated with experimental gastric ulcers. Furthermore, clinical reports also show elevated plasma and gastric mucosal endothelin-1 levels in patients suffering from peptic ulcers.

AIM

To study the possibility that endothelin receptor antagonists may have beneficial effects and prevent the development of gastric ulcers. We have tested in rats the orally-active endothelin antagonist bosentan (Ro 47-0203) and Ro 48-5695, which is 10-30 times more potent than bosentan on endothelin receptors.

METHODS

Water immersion restrained stress (WIRS) and indomethacin were used to provoke gastric mucosal damage. Endothelin receptor antagonists were administered orally prior to the induction of gastric damage. The gastric lesion index (mm), assessed macroscopically, and myeloperoxidase (MPO) activity were used as markers of the extent of mucosal injury.

RESULTS

Bosentan at 100 and 30 mg/kg administered orally caused attenuation of gastric damage in the WIRS model by 58% and 42%, respectively. Bosentan also caused complete reduction of MPO activity. In indomethacin-induced gastric damage, 100 mg/kg bosentan attenuated gastric damage by 45% and 61% as measured by the gastric lesion index and MPO activity respectively. Ro 48-5695 was at least 30 times more potent than bosentan in reducing indomethacin-induced mucosal damage and at 3 mg/kg, caused a decrease of 49% in the gastric lesion index and a reduction in MPO activity of 41%. Bosentan and Ro 48-5695 possess weak antisecretory properties as tested in the mouse gastric gland assay, than cannot, alone, account for their anti-ulcer properties.

CONCLUSIONS

Both endothelin receptor antagonists prevented the development of gastric mucosal injury in the rat. Disturbances in the gastric microcirculation are responsible for the development of experimental gastric ulcers. The anti-ulcer properties of these two endothelin antagonists suggest possible new therapeutic approaches to controlling gastric inflammation.

Increased expression of endothelin receptors in the vasculature of portal hypertensive rats: role in splanchnic hemodynamics

Portal hypertension (PHT) is characterized by increased portal pressure caused in part by a reduction in mesenteric vascular resistance. The aim of this study was to evaluate the role of endothelin (ET) and specific ET receptors in maintaining the vasculopathy of PHT. PHT was created in Sprague-Dawley rats by a partial portal vein ligation. Control animals were sham-operated. ET receptor expression was determined in the superior mesenteric artery of sham and PHT rats by in situ autoradiography, radioligand binding analysis, and reverse-transcription polymerase chain reactions (RT-PCR). The pressor response to ET-1 was determined in vitro using isolated vascular rings and in vivo by measuring mean arterial pressure, splanchnic blood flow, and portal venous pressure following treatment with ET and selective ET receptor antagonists. The pressor response to ET in vitro was significantly enhanced in PHT concomitant with increased ET-A and ET-B receptor expression. There was a significant increase in the peak pressor response to ET (10 microg/kg intravenously) in portal hypertensive rats without any significant change in plasma ET-1 levels. There was no significant difference in the peak splanchnic blood flow or portal venous pressure response following ET-A receptor blockade with JKC-301 infusion (200 microg/kg intravenously). In contrast, ET-B receptor blockade with IRL-1038 (200 microg/kg intravenously) preferentially decreased splanchnic blood flow and portal venous pressure in portal hypertensive rats. These data suggest that enhanced ET-B receptor expression in portal hypertensive vessels contributes to the maintenance of elevated portal pressure in these animals.

Role of endogenous endothelin-1 in stress-induced gastric mucosal damage and acid secretion in rats

In rats subjected to 8 h water-immersion stress, gastric and duodenal mucosal hemorrhage and erosions were detected by macroscopic and histopathological examination. Moreover, plasma and gastric mucosal endothelin-1 (ET-1) levels rose appreciably in a time-related manner during water immersion, with a higher concentration detected in gastric mucosa. Thus, the percentage increases in plasma (gastric mucosal) ET-1, relative to basal levels, after 1, 4 and 8 h of water immersion were 86(172), 169(322) and 210(391)%, respectively. Likewise, a marked increase of gastric acid output was demonstrated 30 min after water immersion and lasted for 3 h. Pretreatment with the endothelin ET(A)/ET(B) receptor blocker, bosentan (30 and 100 mg kg(-1)), orally, dose-dependently antagonized gastric and duodenal mucosal damage as indicated by reductions in lesion lengths of 67 and 80%, respectively. Similar protective effects on mucosa were observed when bosentan was given by the intramuscular route. On the other hand, bosentan suppressed the rate of acid output by 30.3+/-2.1% in the stressed rats, but had no such effect in non-stressed animals. Taken together, results from this study implicate the endogenous peptide, ET-1, as a powerful mediator of stress-evoked gastro-duodenal mucosal damage and, moreover, present bosentan as a potential protector against hyperacidity and mucosal erosion that occur as a consequence of stress.