The effects of bromosulphophthalein, indocyanine green and bilirubin on the biliary excretion of methylmercury

The effects of three ligands for ligandin on the biliary excretion of methylmercury were investigated in male rats injected intravenously with 1.0 mg/kg Hg as Me203 HgCl. Bromosulphophthalein and indocyanine green inhibited the biliary excretion of methylmercury, while bilirubin had no such effect. None of the compounds tested which inhibited the biliary excretion of methylmercury decreased bile flow or changed the hepatic concentration of mercury of non-protein thiols. The possibility of the involvement of ligandin in the biliary excretion of methylmercury is discussed.     

TNF-alpha increases sensitivity to LPS in chronically catheterized rats

Patients with severe trauma injury are transiently exposed to increased serum concentrations of tumor necrosis factor-alpha (TNF-alpha). These patients are susceptible to the development of multisystem organ failure (MSOF) triggered by subsequent exposure to bacterial toxins either via infection or increased intestinal permeability. We simulated the cytokine response of trauma by infusing 0.8 or 8.0 microg/kg of TNF-alpha (priming dose) into chronically catheterized rats. After 48 h, rats were challenged with endotoxin [lipopolysaccharide (LPS); 10 or 1,000 microg/kg]. Animals primed with either dose of TNF-alpha and then challenged with 1,000 microg/kg of LPS demonstrated significantly increased mortality, mean peak serum concentrations of interferon-gamma (IFN-gamma), and blood lactate concentrations (P < 0.05) compared with nonprimed animals. Mean peak serum concentrations of IFN-gamma and blood lactate concentrations were increased after challenge with 10 microg/kg of LPS only in animals primed with 8.0 microg/kg of TNF-alpha. Priming with TNF-alpha did not increase mortality after challenge with 10 microg/kg of LPS. These data suggest that both TNF-alpha release and the subsequent exposure to bacterial toxins mediate the pathophysiological progression from trauma to subsequent MSOF.     

Development of a chronically catheterized maternal-fetal macaque model to study in utero mother-to-fetus HIV transmission: A preliminary report

Abstract: The lack of a representative animal model that permits frequent in utero fetal blood sampling is a major limiting factor for the study of maternal-fetal HIV transmission. Therefore, we have developed a maternal-fetal virus infection model using chronically catheterized macaques to simultaneously study the time-course of viral infection in the mother and the response of the fetus to maternal HIV infection. Pregnant macaques were infected with 10³ infectious units of HIV-2₂₈₇; every 3 days blood samples from both the mother and the fetus as well as amniotic fluid samples were collected. We found a varying degree of peak and time-to-peak virus load, virus-infected PBMCs, and free virus (determined by QC-RNA-PCR method) in maternal blood. Two of the three mothers with more than 10⁸ copies of viral RNA/ml of plasma at peak viremia transmitted the virus to their fetuses at about 14 days post-infection. As observed with HIV-2₂₈₇ infected mothers, virus-infected fetuses also produced a rapid rate of CD4⁺ cell decline in utero.     

吲哚氰绿排泄试验评价肝储备功能与拔管时间的研究

目的:术前评估肝硬化患者肝脏储备功能,及其与患者拔管时间及改良OAA/S评分的关系.方法:对60例肝硬化失代偿患者术前行吲哚氰绿排泄试验.将患者分为三组:按吲哚氰绿15 min储留率(ICGR15)将患者分为两组I1组,I2组,另30例肝功能正常患者为对照组(C组).观测ICGR15与患者拔管时间及改良OAA/S评分的关系.结果:拔管时间I1组与I2组均明显长于C组(P＜0.05或P＜0.01);发生呕吐,烦躁者I1组与I2组均明显多于C组(P＜0.05或P＜0.01),OAA/S评分＞3分者I1组与I2组均多于C组,但无统计学意义.结论:ICGR15对于判断肝硬化患者围术期拔管的时间具有一定的参考价值.     

吲哚氰绿排泄试验评价肝储备功能与拔管时问的研究

目的：术前评估肝硬化患者肝脏储备功能,及其与患者拔管时间及改良OAA/S评分的关系。方法：对60例肝硬化失代偿患者术前行吲哚氰绿排泄试验。将患者分为三组：按吲哚氰绿15min储留率（ICGR15）将患者分为两组I1组,I2组,另30例肝功能正常患者为对照组（C组）。观测ICGR15与患者拔管时间及改良OAA/S评分的关系。结果：拔管时间I1组与I2组均明显长于C组（P〈0.05或P〈0.01）;发生呕吐,烦躁者I1组与I2组均明显多于C组（P〈0.05或P〈0.01）,OAA/S评分〉3分者I1组与I2组均多于C组,但无统计学意义。结论：ICGR15对于判断肝硬化患者围术期拔管的时间具有一定的参考价值。     

Dependence upon bile volume of the biliary excretion of bromocresol green and amaranth in the anaesthetized rat.

The kinetics of the biliary excretion of both bromocresol green and amaranth are better described in terms of rate equations that are functions of the cumulative volume of bile excreted rather than of time. The rate of disappearance of bromocresol green from the liver also appears to depend on the volume of bile excreted rather than on time. It is proposed that bromocresol green, and probably also amaranth, rapidly equilibrates between the hepatic and biliary compartments as a result of reabsorption from the biliary tree and that the rate-limiting factor in the biliary excretion of these dyes is the removal of dye from the biliary tree by bulk flow. Six methods for the graphical presentation of excretion data are examined and their use in the characterization of the kinetics of an excretion system is discussed.     

A model system for investigating the biliary excretion of an anion in the rat.

1. The biliary excretion of phenolphthalein di[35S]sulphate was studied in rats. 2. The conjugate was administered by continuous infusion at rates of 3, 4.5, 6, 9 and 12 mug/min, and kinetic analysis of the rate of biliary excretion was consistent with a two-compartment open-model system. 3. The results obtained after single injections of the ester were also consistent with the model. 4. An essential feature of the model is the presence of a compartment into which the ester may pass as an alternative to direct excretion via the bile. 5. It is suggested that such a compartment may be located within the liver.     

Staphylococcal enterotoxin B potentiates LPS-induced hepatic dysfunction in chronically catheterized rats

Most models of liver dysfunction in sepsis use endotoxin (lipopolysaccharide; LPS) to induce a pathophysiological response. In our study published in this issue (Beno DWA, Uhing MR, Goto M, Chen Y, Jiyamapa-Serna VA, and Kimura RE. Am J Physiol Gastrointest Liver Physiol 280: G858-G865, 2001), the adverse effect of LPS on hepatic function in vivo was only significant at relatively high LPS doses despite high tumor necrosis factor-alpha concentrations. However, many patients with sepsis are exposed to multiple bacterial toxins that may augment the immune response, resulting in increased hepatic dysfunction. We have developed a model of polymicrobial sepsis by parentally administering a combination of staphylococcal enterotoxin B (SEB) and LPS. Using this model, we demonstrate that SEB (50 microg/kg) potentiates the effect of LPS-induced hepatic dysfunction as measured by decreased rates of biliary indocyanine green clearance and bile flow. These increases were most pronounced with doses of 10 and 100 microg/kg LPS, doses that by themselves do not induce hepatic dysfunction. This may explain the seemingly increased incidence and severity of liver dysfunction in sepsis, and it suggests that the exclusive use of LPS for replicating septic shock may not be relevant for studies of hepatic dysfunction.     

The biliary excretion of circulating asialoglycoproteins in the rat.

Following intravenous injection into the rat a small proportion (0.5 – 3.0%) of asialo α₁-acid glycoprotein, asialo fetuin, asialo CEA¹ and native CEA are excreted in an apparently unchanged form in the bile. The maximum excretion rate occurs one hour after injection in all cases. The possibility of a novel pathway for glycoprotein uptake by the liver is discussed.     

Effects of colchicine on the hepatocellular transport of indocyanine green in the rat

The effects of colchicine on plasma elimination and biliary excretion of indocyanine green (ICG) and sulfobromophthalein (BSP) in rats were examined. Elimination of two different doses of ICG (6 mg and 20 mg/kg body weight) from plasma was significantly delayed when rats were treated with colchicine (3 mg/kg body weight) 3 h prior to the administration of the dye. On the other hand, disappearance of BSP (100 mg/kg) from plasma was not influenced by colchicine. The fact that the difference in the ICG elimination from plasma between colchicine-treated and saline-treated rats was minimal in the early period (i.e., 2 min after administration of the dye), but evident after its half-life (i.e., 10 min, when 6 mg/kg body weight of ICG was given), suggested that colchicine mainly affected the hepatocellular transport of ICG rather than the uptake of the dye by hepatocytes. Colchicine also significantly reduced the excretion of ICG (6 mg and 20 mg/kg) into bile but did not alter that of BSP (100 mg and 200 mg/kg). On the other hand, the same amount of lumicolchicine (3 mg/kg) did not have any effect on the biliary excretion of ICG. These results suggested that ICG is transported through hepatocytes into bile with the aid of the cytoplasmic microtubular system, whereas BSP is handled by hepatocytes in a different way.     

The bile flow and biliary excretion of ursocholate in the rat

Several studies reported that ursodeoxycholate (but not its conjugates), when administered intravenously, increased the biliary bicarbonate concentration in the rat (1–3). At the same time, a complete dissociation between bile flow and the bile salt excretion rate was produced in the second hr of infusion (2). In order to examine whether this property was due to the 7β-hydroxy group in its molecular structure, the choleretic property of ursocholate (3α, 7β, 12α-trihydroxy-5β-cholanoic acid) was investigated in male Wistar rats. Immediately after the start of iv infusion of ursocholate at a rate of 1.2 μmole/min/100 g b. wt., both the bile flow and bile salt excretion rate began to increase. However, unlike with ursodeoxycholate, the bile salt excretion rate continued to be high in the second and third hr of infusion, while the bile flow rate gradually increased. Furthermore, the bicarbonate concentration in the bile fell slightly 10 min after the start of ursocholate infusion. Although the concentration tended to return to the baseline value before the bile salt infusion in the later period of observation, no significant increase in bicarbonate concentration was observed during the whole observation period. These properties were quite similar to those of cholate rather than those of ursodeoxycholate. However, a cholate infusion at the same rate of 1.2 μmole/min/100 g b.wt. caused a cholestasis as early as 20 to 30 min after the start of an infusion. These results suggest that the previously reported properties of ursodeoxycholate (that it causes a complete dissociation between the bile flow and bile salt excretion rate in the second hr and that it increases the biliary bicarbonate concentration) were not due to the 7β-hydroxy group in its steroidal structure, and that the choleretic property of ursocholate is similar to its 7α-hydroxy epimar, cholate. However, the much lower cytotoxicity of ursocholate compared to cholate appears to be due to the 7β-hydroxy group that ursocholate has.     

Hepatic storage and biliary excretion of rose bengal in the rat

The distribution of intravenously administered rose bengal (RB) depends on its dose. At a low dose (10 mg/kg), RB can be found almost solely in the liver and plasma. However, at higher doses (from 25 up to 200 mg/kg) the amount of RB found in extra-hepatic tissues gradually increases. In this experiment the hepatic transfer maximum of RB amounted to 146 micrograms/kg/min. By increasing the dose from 10 to 200 mg/kg, the hepatic concentration of RB also approached a maximum (1250 micrograms/g). The storage capacity of the liver, however, did not limit the transfer maximum of RB.     

Inhibition of biliary taurocholate excretion during menadione metabolism in perfused rat liver

In perfused rat liver menadione elicits substantial oxidation in both the NADPH and GSH redox systems. Biliary excretion of GSSG is increased several-fold. Menadione derivatives appear in the bile predominantly as the menadione-S-glutathione conjugate, thiodione (60%), or as conjugates derived therefrom (17%). About 10% appear as menadione glucuronides. The excretion of taurocholate into bile is strongly inhibited upon menadione infusion. The inhibition of taurocholate excretion is small in livers with a low content of Se-GSH-peroxidase and in glutathione-depleted livers. In these livers intracellular GSSG and biliary GSSG release remain at low values, although menadione still imposes oxidative stress as indicated by an oxidation of intracellular NADPH. Under anoxic conditions menadione has little influence on both the NADPH and GSH redox systems and also on biliary taurocholate excretion. The amount of thiodione released into bile is similar to that found under normoxia, whereas the amount of glucuronidated products almost doubled. We conclude (a) that intracellular formation of GSSG by menadione occurs via the generation of hydrogen peroxide; (b) that the inhibition of biliary taurocholate excretion by menadione is related to the increased formation of glutathione disulfide; and (c) that menadione derivatives show little, if any, contribution to the inhibition of taurocholate excretion.