Inhibition of glucagon improves splanchnic hyporesponse to terlipressin in cirrhotic rats with blood retention in the gastric lumen

Potential stagnation in the splanchnic hemodynamics demonstrated by the dynamic microbubbles in chronic liver disease

BACKGROUND AND AIM

Impaired splanchnic hemodynamics are well-documented phenomena in cirrhosis. However, comprehensive hemodynamic features from the superior mesenteric artery (SMA) to the superior mesenteric vein (SMV) via intestinal capillaries have not been studied. The aim was to examine splanchnic hemodynamics and their relationship with clinical presentations.

METHODS

Contrast-enhanced ultrasound was performed for both the SMA and SMV under fasting conditions and postprandially following ingestion of a liquid diet. The microbubble traveling time (MTT) was determined as the difference between the contrast onset in the SMA and SMV, indicating the time required for microbubble transit through the splanchnic circulation.

RESULTS

There were 192 subjects for fasting conditions (81 cirrhosis, 72 chronic hepatitis, 39 healthy controls), and 74/192 for postprandial conditions (44 cirrhosis, 11 chronic hepatitis, 19 healthy controls). The MTT (fasting; postprandial) was significantly longer in cirrhosis (7.7 ± 2.9 s; 7.0 ± 0.3 s) than in controls (5.4 ± 2.3 s, P < 0.001; 3.9 ± 0.9 s, P<0.001) and chronic hepatitis (6.3 ± 2.5 s, P=0.007; 5.1 ± 1.4 s, P=0.013). The MTT ratio (postprandial/fasting) showed disease-related changes: 0.75 ± 0.20 in controls, 0.78 ± 0.15 in chronic hepatitis, and 1.00 ± 0.28 in cirrhosis (P=0.003, vs controls; P=0.036, vs chronic hepatitis).

CONCLUSIONS

The real-time observation of traveling microbubble on the sonogram revealed a prolonged transit with a weak postprandial response in the intestinal circulation, suggesting better understanding of underlying pathophysiology of splanchnic hemodynamics in chronic liver disease.

Concomitant inhibition of oxidative stress and angiogenesis by chronic hydrogen-rich saline and N-acetylcysteine treatments improves systemic, splanchnic and hepatic hemodynamics of cirrhotic rats

AIM

In cirrhosis, increased oxidative stress leads to systemic and splanchnic hyperdynamic circulation, splanchnic angiogenesis, portosystemic collateral formation, hepatic endothelial dysfunction, increased intrahepatic resistance and the subsequent portal hypertension. Like N-acetylcysteine, hydrogen-rich saline is a new documented antioxidant with the potential to treat the complications of liver diseases.

METHODS

In this study, hemodynamics, splanchnic angiogenesis and hepatic endothelial dysfunction were measured in common bile duct ligation (BDL)-cirrhotic rats receiving 1-month treatment of vehicle, N-acetylcysteine and hydrogen-rich saline immediately after BDL. Additionally, acute effects of N-acetylcysteine and hydrogen-rich saline on vascular endothelial growth factor (VEGF)-induced tubule formation and migration of human umbilical vein endothelial cells (HUVEC) were also evaluated.

RESULTS

The data indicate that 1-month treatment of N-acetylcysteine or hydrogen-rich saline significantly ameliorated systemic and splanchnic hyperdynamic circulation, corrected hepatic endothelial dysfunction, and decreased intrahepatic resistance and mesenteric angiogenesis by inhibiting inflammatory cytokines, nitric oxide, VEGF and reducing mesenteric oxidative stress in cirrhotic rats. In vivo studies revealed that acute co-incubation of N-acetylcysteine or hydrogen-rich saline with VEGF effectively suppressed VEGF-induced angiogenesis and migration of HUVEC accompanied by decreasing of oxidative stress and inflammatory cytokines.

CONCLUSION

Both hydrogen-rich saline and N-acetylcysteine alleviate portal hypertension, the severity of portosystemic collaterals, mesenteric angiogenesis, hepatic endothelial dysfunction and intrahepatic resistance in cirrhotic rats. N-Acetylcysteine and the new antioxidant, hydrogen-rich saline are potential treatments for the complications of cirrhosis.

Population pharmacokinetics and pharmacodynamics of ribavirin in patients with chronic hepatitis C genotype 1 infection

We report a population pharmacokinetic (PK) and pharmacodynamic (PD) model of orally administered ribavirin in patients with chronic hepatitis C virus (HCV) infection enrolled in a multicenter clinical trial, including the estimation of covariate effects on ribavirin PK parameters and sustained viral response (SVR). Ribavirin concentrations obtained from 144 patients, consisting of n = 71 African American (AA) and n = 73 Caucasian Americans (CA), during 24 weeks of therapy were best described by a two-compartment model with first-order absorption and elimination parameterized in terms of apparent oral clearance (CL/F), apparent central volume (Vc/F), apparent peripheral volume (Vp/F), and apparent intercompartmental clearance (Q/F). The typical population parameters were CL/F (19.0 L/h), Vc/F (1,130 L), Vp/F (4,020 L), and Q/F (38.6). The Vp/F was approximately 50% greater in AA compared to CA. Significant covariates in the SVR model included IL-28B genotype, homeostasis model assessment of insulin resistance, and ribavirin exposure during the first week (AUC(0-7)). The population PK and logistic regression models both described the observed ribavirin concentration data and SVR data well. These findings suggest that optimization of ribavirin plasma concentrations during the first week of ribavirin dosing is most critical in AA patients in order to increase the rate of SVR, especially those with the IL-28B TT genotype.

The relationship between endotoxemia and hepatic endocannabinoids in cirrhotic rats with portal hypertension

BACKGROUND & AIMS

Cirrhosis is characterized by endotoxemia and increased intrahepatic resistance, which is caused by hepatic fibrosis and endothelial dysfunction, as well as the activated endocannabinoids system, including cannabinoid (CB(1) and CB(2)) receptors. Besides accelerating hepatic fibrogenesis, endotoxins induce the release of circulating endocannabinoids and portal hypertension in cirrhosis. This study examines how suppression of endotoxemia by antibiotics affects intrahepatic resistance and the hepatic endocannabinoid system in bile-duct-ligated (BDL) rats.

METHODS

Measurements were performed that included: mean arterial pressure, cardiac index (CI), systemic vascular resistance, superior mesenteric arterial blood flow and resistance, PVP, plasma endotoxin and hepatic tumor necrosis factor-α (TNFα), anandamide and 2-arachidonylglycerol, hepatic expression of cannabinoid receptors, endothelial nitric oxide synthase (eNOS), phospho-eNOS, Akt, phospho-Akt and thromboxane synthase (TXS), matrix metalloproteinase-2 (MMP-2), tissue inhibitor of metalloproteinase-2 (TIMP-2), hepatic fibrosis, and leukocyte infiltration. Hepatic endothelial dysfunction was evaluated in BDL rats receiving vehicle (BDL-V) or 2-weeks of ciprofloxacin (BDL-cipro).

RESULTS

Plasma endotoxin and hepatic TNFα, anandamide and 2-arachidonylglycerol, expression of TXS, MMP-2, TIMP-2, hepatic fibrosis and infiltration of hepatic leukocytes, CI, PVP and intrahepatic resistance were significantly lower in BDL-cipro than in BDL-V rats. Conversely, systemic vascular resistance, eNOS and Akt phosphorylation were significantly higher in BDL-cipro than in BDL-V rats. Improvement of hepatic endothelial dysfunction was associated with lower expression of hepatic CB(1) and a higher expression of hepatic CB(2) in BDL-cipro rats.

CONCLUSIONS

In cirrhotic rats, ciprofloxacin suppressed endotoxemia and the hepatic endocannabinoid system thus ameliorating hyperdynamic circulation and decreased intrahepatic resistance by preventing hepatic fibrogenesis and endothelial dysfunction.

Research progress in the mechanism of renal vasoconstriction in hepatorenal syndrome

Hepatorenal syndrome (HRS) is defined as the development of renal failure in patients with severe liver disease in the absence of any other identifiable cause of renal pathology. The hallmark of HRS is renal vasoconstriction. The cause of renal vasoconstriction may involve several factors: activation of renal nervous system, imbalance of renal vasoactive mediators and molecular mechanism. In this review, we summarize the above progress.