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Background: Skeletal muscle (SM) is a key factor in cancer treatment. However, it is unclear whether pretreatment SM change affects the outcome of immune checkpoint inhibitors (ICIs) therapy in gastric cancer (GC)., Methods: Advanced GCs treated with ICIs were retrospectively investigated. SM evaluated by psoas muscle area at the third lumbar vertebra was measured on CT acquired within 1 month from the start of ICIs therapy (CT-1), and on CT acquired 2.8 ± 0.84 months before CT-1. Monthly change rate of SM (MCR-SM) was defined as the change rate of SMs between those two CTs divided by the period between those CTs (month). Monthly change rate of body weight (MCR-BW) during the same period was also calculated. They were compared with disease-specific survival (DSS) and progression-free survival (PFS). MCR-SM was compared with pretreatment markers including neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), monocyte-to-lymphocyte ratio (MLR), C-reactive protein (CRP), and liver-to-spleen CT attenuation ratio (LSR) as a marker of liver lipid metabolism., Results: This study enrolled eighty-three GC patients. MCR-SM significantly correlated with DSS and PFS (P < 0.0001, 0.001, respectively), whereas MCR-BW did not. Kaplan-Meier analyses demonstrated that higher MCR-SM (MCR-SM ≥ -0.7185%) significantly associated with better DSS and PFS (P = 0.0002, 0.03, respectively). Patients with positive MCR-SM showed significantly lower NLR, MLR, and CRP than those with negative (P = 0.01, 0.006, 0.003, respectively). MCR-SM showed a significant positive correlation with LSR (P = 0.007, R = 0.30)., Conclusions: Pretreatment SM loss, associated with high systemic inflammation and hepatic fat accumulation, related to poor outcome of ICIs therapy in GC., (© 2024. The Author(s).)

Leptin action in the brain has emerged as an important regulator of liver function independently from its effects on food intake and body weight. The autonomic nervous system plays a key role in the regulation of physiological processes by leptin. Here, we used direct recording of nerve activity from sympathetic or vagal nerves subserving the liver to investigate how brain action of leptin controls hepatic autonomic nerve activity. Intracerebroventricular (ICV) administration of leptin activated hepatic sympathetic traffic in rats and mice in dose- and receptor-dependent manners. The hepatic sympatho-excitatory effects of leptin were also observed when leptin was microinjected directly into the arcuate nucleus (ARC), but not into the ventromedial hypothalamus (VMH). Moreover, using pharmacological and genetic approaches, we show that leptin-induced increase in hepatic sympathetic outflow depends on PI3K but not AMP-activated protein kinase (AMPK), STAT3, or ERK1/2. Interestingly, ICV leptin also increased hepatic vagal nerve activity in rats. We show that this response is reproduced by intra-ARC, but not intra-VMH, leptin administration and requires PI3K and AMPK. We conclude that central leptin signaling conveys the information to the liver through the sympathetic and parasympathetic branches of the autonomic nervous system. Our data also provide important insight into the molecular events underlying leptin's control of hepatic autonomic nerve activity by implicating PI3K and AMPK pathways., (Copyright © 2015 the authors 0270-6474/15/350474-11$15.00/0.)

Transgenic rat gene mutation assays can be used to assess genotoxicity of chemicals in target organs for carcinogenicity. Mutations in transgenes are genetically neutral and accumulate during a treatment period; thus, the assays are suitable for assessment of the genotoxicity risk of chemicals using a repeated-dose treatment paradigm. However, few such studies have been conducted. To examine the utility of the transgenic rat assays in repeated-dose studies, we treated female F344 gpt delta rats with tamoxifen (TAM) at 20 and 40mg/kg, or toremifene (TOR) at 40mg/kg by gavage daily for 3 weeks. We also fed gpt delta rats with TAM at either 250ppm (15.4-17.6mg/kg) or 500ppm (30.0-32.9mg/kg) for 13 weeks. TAM is carcinogenic in the rat liver and TOR is not carcinogenic. TAM administration significantly increased gpt (point mutations) and Spi(-) (deletions) mutant frequencies (MFs) in the liver, the target organ of carcinogenesis; MFs were higher after treatment for 13 weeks than after treatment for 3 weeks. The MFs in the kidney did not increase in any of the TAM treatment groups. TOR had no effect on MFs (gpt and Spi(-)) in either the liver or the kidney. We conclude that the gpt delta rat assay in the repeated-dose treatment paradigm is sensitive enough to detect gene mutations induced by TAM in the target organ for carcinogenesis. Furthermore, the assay can be integrated into a 13-week dose-finding study for a 2-year cancer bioassay., (Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.)

Background: It is reported that mast cells are involved in ischemia-reperfusion (I/R) injury of several organs such as intestine, heart, and brain in rats. However, the roles of mast cells are not known in rat hepatic I/R injury. We determined using genetically mast cell deficient (Ws/Ws) rats whether mast cells participate in the genesis of hepatic I/R injury., Methods: Isolated livers from male Ws/Ws rats (n = 6), their wild type +/+ rats (n = 6), and Sprague Dawely (SD) rats (n = 12) were perfused portally with diluted blood (Hct 8%) at a constant blood flow. Ischemia was induced at room temperature by occlusion of the inflow line of the portal vein for 1 h, followed by 1-h reperfusion in a recirculating manner. The pre- and post-sinusoidal resistances were determined by measuring the portal venous pressure (Ppv), hepatic venous pressure, blood flow and the sinusoidal pressure, which was assessed by the double occlusion pressure (Pdo). Liver injury was assessed by blood alanine aminotransferase (ALT) levels, bile flow rate and histology of the livers., Results: In the +/+ group, liver injury occurred after reperfusion; blood ALT levels increased from 19 ± 4 (SD) to 71 ± 18 and 135 ± 30 (IU/L) at 30 and 60 min, respectively, and bile flow decreased to 51% ± 6% of the baseline at 60 min after reperfusion. Histologic examination revealed marked hepatic degeneration. Similar changes were observed in the Ws/Ws rats and the SD rats (n = 6), and there were no significant differences in the variables among the Ws/Ws, +/+, and SD groups. In any ischemia groups, immediately after reperfusion, Ppv substantially, but Pdo only slightly, increased, followed by a return towards the baseline, indicating a predominant increase in pre-sinusoidal resistance over post-sinusoidal resistance. Liver weight significantly increased at 60 min after reperfusion. In the control SD rats without I/R (n = 6), no significant changes were observed in the variables., Conclusions: I/R injury occurs in the absence of hepatic mast cells in the isolated perfused rat liver model of I/R injury., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Vasopressin, a vasoactive peptide, causes vasoconstriction via V1a vasopressin receptors. Unlike other vasoconstrictor agents, vasopressin also has vasodilatory properties. The purpose of this study was to determine the effect of vasopressin on hepatic and splanchnic circulation in Sprague- Dawley rats. The experiments were conducted in not only isolated blood- and constant flowperfused livers but also anesthetized spontaneously breathing rats. In anesthetized rats, portal venous pressure (Ppv), systemic arterial pressure (Psa), central venous pressure, and hepatic blood flow (HBF) of combined portal venous and hepatic arterial blood flow were continuously measured, and splanchnic vascular bed resistance (Rspl) defined by (Psa - Ppv) / HBF was determined. In perfused livers, vasopressin at 0.1-1,000 nM caused weak venoconstriction as evidenced by small increase in Ppv. In anesthetized rats, when vasopressin was injected into the portal vein as a bolus consecutively at 0.01-100 nmol/kg, Psa increased dose-dependently with the peak increment of 60 ± 18 mmHg at 100 nmol/kg. Ppv and HBF decreased, with resultant increase in Rspl, indicating splanchnic vasoconstriction. In conclusion, hepatic venoconstrictor action of vasopressin was weak in rats. Vasopressin causes splanchnic vasoconstriction, resulting in a decrease in HBF and Ppv in anesthetized rats.

Aims: Ethanol constricts hepatic vessels of isolated perfused livers of rats, but not dogs. However, it is not known whether ethanol constricts or dilates the hepatic vessels in other species such as guinea pigs and mice. In addition, the sites of hepatic venoconstriction induced by ethanol were not known in rat livers. We therefore studied the effects of ethanol on the segmental hepatic vascular resistance and liver weight of mice, rats and guinea pigs., Methods: The isolated livers were portally perfused with diluted blood at constant flow. The sinusoidal pressure was measured by the double occlusion method and was used to determine the pre- and post-sinusoidal resistance. The change of liver weight was also measured. Ethanol was administered cumulatively into the perfusate to gain clinically relevant concentrations of 1-300 mM., Results: Ethanol dose dependently caused predominant pre-sinusoidal constriction in livers of all three species. When compared with the livers of the guinea pigs and rats, the mouse livers were the weakest in response. Dose-dependent decreases in liver weight and bile flow accompanied predominant pre-sinusoidal constriction in guinea pigs and rats., Conclusion: Ethanol predominantly constricts pre-sinusoids in rat, guinea pig and mouse livers, although the mouse liver response was much weaker. Ethanol-induced pre-sinusoidal constriction is accompanied by reduction of liver blood volume in guinea pigs and rats.

We determined the hepatic volume change in anaphylactic hypotension by using four ultrasonic crystals in anesthetized rats. The hepatic volume was measured with four ultrasonic crystals arranged to form a tetrahedron on the liver surface. Before in vivo experiments, using isolated perfused rat liver preparations, we compared the measured liver volume changes with the whole-liver weight changes during hepatic blood flow rate changes and venoconstriction induced by norepinephrine. The measured relative change of the tetrahedron volume (V[utc]; percentage changes of the initial volume) was closely correlated with the liver weight change (W; percentage changes of the initial liver weight): V(utc) = 0.85W - 4.11 (r² = 0.67). Then, we measured the liver weight and the tetrahedron volume during hepatic anaphylaxis in isolated perfused liver excised from the rats sensitized with ovalbumin. An injection of the antigen into the perfusate caused anaphylactic venoconstriction, liver weight loss (1.1 ± 0.3 g; 9% ± 1%), and the tetrahedron volume reduction (12% ± 4%). Finally, we measured the liver volume change during anaphylactic hypotension in anesthetized ovalbumin-sensitized rats. When the antigen was i.v. injected into anesthetized rats, along with systemic hypotension and hepatic venoconstriction, the liver tetrahedron volume decreased by 6% ± 2% from baseline. In conclusion, we established a method to measure the hepatic volume by using four ultrasonic crystals forming a tetrahedron. Using this ultrasonic crystal method, we demonstrated that liver volume decreases during anaphylactic hypotension in anesthetized rats.

1. Exercise training attenuates circulatory shock due to haemorrhage, endotoxin or heatstroke. However, it remains unknown whether exercise training attenuates anaphylactic shock. Hepatic venoconstriction is involved in rat anaphylactic hypotension. In the present study, we determined the effects of exercise training on both anaphylaxis-induced segmental venoconstriction in rat perfused livers and systemic anaphylaxis in conscious rats. The role of nitric oxide (NO) in the effect of exercise on the venoconstriction of perfused livers was also examined. 2. Rats were subjected to running training on a motorized treadmill for 4 weeks. Two weeks prior to the anaphylaxis experiment, Sprague-Dawley rats were actively sensitized with the antigen ovalbumin. In isolated livers perfused portally with blood, the portal venous pressure (P(pv)) and sinusoidal pressure were measured to determine the pre- and post-sinusoidal resistances (R(pre) and R(post), respectively). In conscious rats, systemic arterial pressure (SAP) and P(pv) were determined. 3. In the perfused livers of sedentary rats, antigen administration led to a predominant presinusoidal constriction, as evidenced by 4.6- and 1.7-fold increases in R(pre) and R(post), respectively. The anaphylaxis-induced increase in R(pre) was significantly attenuated by 24% by exercise training. Inhibition of NO synthase with N(G)-nitro-L-arginine methyl ester (100 micromol/L) 10 min prior to the injection of antigen enhanced anaphylactic venoconstriction, but did not alter the effect of exercise training on the increase in R(pre). In contrast, exercise training did not attenuate either anaphylactic hypotension or portal hypertension in conscious rats. 4. In conclusion, exercise training attenuates the anaphylaxis-induced presinusoidal constriction in rat isolated perfused livers, independent of NO production. However, this action is not evident in conscious rats and exercise training does not affect anaphylactic hypotension in conscious rats.

Objective: Hepatic venoconstriction plays a significant role in anaphylactic hypotension in anesthetized rats. The purpose of this study is to determine whether the primary site of anaphylactic venoconstriction in the liver venous circulation occurs prior to or distal to the sinusoidal capillaries. We also determined whether the hepatic blood volume is increased during anaphylactic hypotension., Methods: We measured, using a servo-null micropipette pressure-measuring system, the hepatic venular transmural pressure (P micro hv) at the liver surface of anesthetized rats sensitized with the antigen of ovalbumin (1 mg). We also measured the liver lobe thickness, using the ultrasonic crystal dimension measuring system. Anaphylactic hypotension was induced by an intravenous injection of 0.6 mg ovalbumin., Results: When the antigen was injected, the systemic arterial pressure decreased profoundly from 118+/-9 to 45+/-4 mm Hg, which was accompanied by an increase in Ppv and P micro hv: P micro hv only transiently increased from 3.1+/-0.9 to 8.8+/-1.5 cm H(2)O at 1 min and then rapidly returned to the baseline within 2 min, when Ppv continued to increase and reached the peak of 36+/-7 cm H(2)O at 3.5 min after antigen. This greater increase in Ppv-to-P micro hv gradient than that in P micro hv-to-Pcv gradient after antigen indicated that the constriction of the portal veins and the sinusoids much predominates over that of the hepatic veins. Along with this hepatic pre- and sinusoidal constriction, the liver lobe thickness significantly decreased by 4% after antigen., Conclusion: Pre-sinusoidal constriction during anaphylactic shock in anaesthetized rats increased the portal venous pressure while the hepatic venular pressure only increased slightly and transiently. This predominant pre-sinusoidal constriction is accompanied by a decrease in liver volume.

Hepatic anaphylactic venoconstriction is partly involved in anaphylactic hypotension. We determined the chemical mediators responsible for anaphylaxis-induced segmental venoconstriction in perfused livers isolated from ovalbumin-sensitized rats. Livers were perfused portally and recirculatingly at constant flow with diluted blood. The portal venous pressure (Ppv), hepatic venous pressure (Phv), liver weight and hepatic oxygen consumption were continuously measured. The sinusoidal pressure was measured by the double occlusion pressure (Pdo), and was used to determine the pre-sinusoidal (Rpre) and post-sinusoidal (Rpost) resistances. After antigen injection, both Ppv and Pdo increased, resulting in 5.6- and 1.6-fold increases in Rpre and Rpost, respectively. Liver weight showed a biphasic change of an initial decrease followed by an increase. Hepatic oxygen consumption significantly decreased after antigen. Anaphylaxis-induced increase in Rpre was most extensively inhibited by 38.6% by pretreatment with ONO-1078 (100 microM, a cysteinyl leukotriene receptor-1 antagonist), among all antagonists or inhibitors administrated individually including TCV-309 (20 microM), AA-2414 (10 microM), ketanserin (10 microM) and indomethacin (10 microM). Combined pretreatment with indomethacin and ONO-1078 exerted additive inhibitory effects and attenuated Rpre by 65.8%. However, TCV-309, a platelet activating factor (PAF) receptor antagonist, did not affect the anaphylactic response. In contrast, anaphylaxis-induced increase in Rpost was attenuated only by ONO-1078 combined pretreatment. The antigen-induced changes in liver weight and hepatic oxygen consumption were attenuated significantly when hepatic venoconstriction was attenuated. It is concluded that cysteinyl leukotrienes and cyclooxygenase products, but not PAF, are mainly involved in anaphylaxis-induced pre-sinusoidal constriction in isolated perfused rat livers.

Platelet-activating factor (PAF), one of vasoconstrictive lipid mediators, is involved in systemic anaphylaxis. On the other hand, nitric oxide (NO) is known to attenuate anaphylactic venoconstriction of the pre-sinusoids in isolated guinea pig and rat livers. However, it is not known whether NO attenuates PAF-induced hepatic venoconstriction. We therefore determined the effects of L-NAME, a NO synthase inhibitor, on PAF-induced venoconstriction in blood- and constant flow-perfused isolated livers of mice, rats and guinea pigs. The sinusoidal pressure was measured by the double occlusion pressure (Pdo), and was used to determine the pre- (Rpre) and post-sinusoidal (Rpost) resistances. PAF (0.01-1 microM) concentration-dependently caused predominant pre-sinusoidal constriction in all livers of three species studied. The guinea pig livers were the most sensitive to PAF, while the mouse livers were the weakest in responsiveness. L-NAME pretreatment selectively increased the basal Rpre in all of three species. L-NAME also significantly augmented the PAF-induced increases in Rpre, but not in Rpost, in rat and guinea pig livers. This augmentation was stronger in rat livers than in guinea pig livers at the high concentration of 0.1 microM PAF. However, L-NAME did not augment PAF-induced venoconstriction in mouse livers. In conclusion, in rat and guinea pig livers, NO may be released selectively from the pre-sinusoids in response to PAF, and then attenuate the PAF-induced pre-sinusoidal constriction. In mouse liver, PAF-induced venoconstriction is weak and not modulated by NO.

Background: Hepatic ischemia-reperfusion (I/R) is accompanied by liver weight gain and ascites formation possibly caused by an increase in the sinusoidal pressure, a determinant of hepatic transvascular fluid movement. However, changes in the sinusoidal pressure during hepatic I/R in mice are not known. It is also controversial whether nitric oxide (NO) exerts a beneficial or detrimental effect on hepatic I/R injury. We determined the changes in hepatic sinusoidal pressure and liver weight, and the effect of a NO synthase inhibitor, N(G)-nitro-L-arginine methyl ester (L-NAME) on I/R injury of isolated mouse liver., Materials and Methods: Isolated liver from 20 male outbred ddY mice was perfused portally with diluted blood (Hct 3%). After pretreatment with L-NAME (100 microm) or D-NAME (100 microm), ischemia was induced at room temperature by occlusion of the inflow line of the portal vein for 1 h followed by 1-h reperfusion in a recirculating manner. The sinusoidal pressure was assessed by the double vascular occlusion pressure (Pdo), and pre- and postsinusoidal resistance was determined. Liver injury was assessed by blood levels of alanine aminotransferase (ALT)., Results: In the d-NAME group (n=7), immediately after reperfusion, the portal pressure increased by 2.8 +/- 0.1 (SE) mmHg, which was accompanied by an increase in Pdo of 1.5 +/- 0.1 mmHg, indicating increases in pre- and postsinusoidal resistance to a similar degree. Then, presinusoidal, but not postsinusoidal, resistance sustained increased until 60 min after reperfusion. Liver weight increased to 0.14 +/- 0.04 g/g liver after reperfusion, followed by a gradual return to baseline. Blood ALT levels increased at 60 min after reperfusion. There were no significant differences in changes in the variables between the D- and L-NAME (n=7) groups. In the time-matched non- I/R control group (n=6), no changes in variables were observed for 2 h., Conclusions: Mouse hepatic I/R causes marginal liver weight gain associated with a small and transient increase in the sinusoidal pressure, and nitric oxide does not play any significant roles in this injury.

Growth hormone (GH) transgenic amago salmon (Oncorhynchus masou) were generated with a construct containing the sockeye salmon GH1 gene fused to the metallothionein-B (MT-B) promoter from the same species. This transgene directed significant growth enhancement with transgenic fish reaching approximately four to five times greater weight than control salmon in F(2) and F(3) generations. This drastic growth enhancement by GH transgene is well known in fish species compared with mammals, however, such fish can show morphological abnormalities and physiological disorders like other GH transgenic animals. GH is known to have many acute effects, but currently there are no data describing the chronic effects of over-expression of GH on various hepatic genes in GH transgenic fish. Hepatic gene expression is anticipated to play very important roles in many physiological functions and growth performance of transgenic and control salmon. To examine these effects, we performed subtractive hybridization (using cDNA generated from liver RNA) in both directions to identify genes both increased and decreased in transgenic salmon relative to controls (576 clones were isolated and sequenced in total). Heme oxygenase, vitelline envelope protein, Acyl-coA binding protein, NADH dehydrogenase, mannose binding lectin-associated serine protease, hemopexin-like protein, leucyte-derived chemotaxin2 (LECT2), and many other genes were obtained in higher clone frequencies suggesting enhanced expression. In contrast, complement C3-1, lectin, rabin, alcohol dehydrogenase, Tc1-like transposase, Delta6-desaturase, and pentraxin genes were obtained in lower frequencies. Microarray analysis was also performed to obtain quantitative expression data for these subtracted cDNA clones. Analysis of fish across seasons was also conducted using both F(2) and F(3) salmon. Results of the microarray data essentially corresponded with those of the subtraction data when both F(2) and F(3) fish were completely immature, but the expression pattern was changed when fish approached maturation. Genes showing enhanced expression in GH transgenic fish in F(2) and F(3) by array analysis were vitelline envelope protein, hemopexin-like protein, heme-oxygenase, inter alpha-trypsin inhibitor, LECT2, GTP cyclohydrolase I feedback regulatory protein (GFRP), and bikunin. Reduced expression genes were lectin, Delta6-desaturase, apolipoprotein, and pentraxin. In particular, lectin was found to be highly suppressed in all F(2) and immature F(3) salmon. Further, serum lysozyme activity, one of innate immunity, was significantly (p<0.05) decreased in both F(2) and F(3) GH transgenic fish. These results indicate that the GH transgene fish had altered hepatic gene expression relating to iron-metabolism, innate immunity, reproduction, and growth.

Aim: The purpose of this study was to determine whether anaphylactic hypotension in rabbits is accompanied by hepatic venoconstriction, and the effects of anaphylaxis on hepatic segmental vascular resistances and liver weight in isolated perfused rabbit livers., Methods: The rabbits were sensitized by subcutaneous injection of antigen of 2.5 mg ovalbumin with complete Freund's adjuvant three times at 1 week interval. One week after sensitization, anaphylaxis was induced by an injection of 2.5 mg ovalbumin into the jugular vein of pentobarbital anaesthetized rabbits or the perfusate of rabbit livers perfused via the portal vein at a constant flow. Using the double occlusion technique to estimate the hepatic sinusoidal pressure, pre- (R(pre)) and post-sinusoidal (R(post)) resistances were calculated for the isolated perfused livers., Results: An antigen injection into the sensitized rabbits caused not only a decrease in systemic arterial pressure from 79 +/- 2 to 40 +/- 4 mmHg, but also an increase in portal venous pressure (P(pv)) from 9.5 +/- 2.2 to 24.1 +/- 3.9 cmH(2)O. Portal hypertension persisted for 8 min after the antigen injection. An injection of antigen into the perfusate caused a marked increase in P(pv) from 5.4 +/- 0.1 to 28.6 +/- 2.4 cmH(2)O at 6 min, but only a slight increase in double occlusion pressure from 2.2 +/- 0.2 to 3.8 +/- 0.2 cmH(2)O, resulting in a selective increase in R(pret) rather than R(post). Concomitant with the hepatic pre-sinusoidal constriction, liver weight loss occurred., Conclusion: Anaphylactic hypotension in rabbits is accompanied by hepatic venoconstriction which is characterized by pre-sinusoidal contraction.

1. The effects of the nitric oxide (NO) synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME) on anaphylaxis-induced venoconstriction were examined in rat isolated livers perfused with blood-free solutions in order to clarify the role of NO in anaphylactic venoconstriction. 2. Rats were sensitized with ovalbumin (1 mg) and, 2 weeks later, livers were excised and perfused portally in a recirculating manner at a constant flow with Krebs'-Henseleit solution. The antigen (ovalbumin; 0.1 mg) was injected into the reservoir 10 min after pretreatment with L-NAME (100 micromol/L) or D-NAME (100 micromol/L) and changes in portal vein pressure (Ppv), hepatic vein pressure (Phv) and perfusate flow were monitored. In addition, concentrations of the stable metabolites of NO ( and ) were determined in the perfusate using an HPLC-Griess system. 3. The antigen caused hepatic venoconstriction, as evidenced by an increase in Ppv from a mean (SEM) baseline value of 7.7 +/- 0.1 cmH2O to a peak of 21.4 +/- 1.1 cmH2O at 3 min in D-NAME-pretreated livers. Pretreatment with L-NAME augmented anaphylactic venoconstriction, as reflected by a higher Ppv (27.4 +/- 0.8 cmH2O) after antigen than observed following D-NAME pretreatment. The addition of L-arginine, a precursor for the synthesis of NO, reversed the augmentation of anaphylactic venoconstricion by L-NAME. This suggests that hepatic anaphylaxis increased the production of NO, which consequently attenuated anaphylactic venoconstriction. However, perfusate NOx levels did not increase significantly after antigen in livers pretreated with either L-NAME or D-NAME. 4. In conclusion, L-NAME potentiates rat anaphylactic hepatic venoconstriction, suggesting that NO contributes to the attenuation of the venoconstriction. However, this functional evidence was not accompanied by corresponding changes in perfusate NOx concentrations.

Anaphylactic shock is accompanied by a decrease in oxygen consumption. However, it is not well known whether oxygen consumption decreases during local anaphylactic reaction in liver. We determined the effects of anaphylaxis and norepinephrine on oxygen consumption in isolated rat livers perfused portally and recirculatingly at constant flow with blood (hematocrit, 12%). Oxygen consumption was continuously measured by monitoring the portal-hepatic venous oxygen saturation differences using the absorption spectrophotometer, the probes of which were built in perfusion lines. Hepatic anaphylaxis was induced by an injection of ovalbumin (0.01 or 0.1 mg) into the perfusate of the isolated liver of the rat sensitized with subcutaneous ovalbumin (1 mg). Hepatic venoconstriction and liver weight loss were similarly observed in response to norepinephrine (0.01-10 micromol L(-1)) and anaphylaxis. However, hepatic anaphylaxis reduced oxygen consumption, whereas norepinephrine increased it. There was a possibility that anaphylactic venoconstriction could reduce the perfused surface area, resulting in decreased oxygen consumption. However, pretreatment with a vasodilator of sodium nitroprusside substantially attenuated venoconstriction but not the decrease in oxygen consumption during anaphylaxis. Thus, we conclude that local hepatic anaphylaxis decreases oxygen consumption independently of venoconstriction in isolated blood-perfused rat livers.

Vasoconstrictive lipid mediators, thromboxane A(2) (TxA(2)), platelet-activating factor (PAF) and leukotriene D(4) (LTD(4)) have been implicated as mediators of liver diseases. There are species differences in the primary site of hepatic vasoconstriction in response to these mediators. We determined the effects of a TxA(2) analogue (U-46619), PAF and LTD(4) on the vascular resistance distribution, weight and oxygen consumption of isolated rat livers portally perfused with blood. The sinusoidal pressure was measured by the double occlusion pressure (P(do)), and was used to determine the pre- (R(pre)) and post-sinusoidal (R(post)) resistances. All these three mediators increased the hepatic total vascular resistance (R(t)). The responsiveness to PAF was 100 times greater than that to U-46619 or LTD(4). Both of PAF and U-46619 predominantly increased R(pre) over R(post). At the comparable increased R(t) levels, U-46619 more preferentially increased R(pre) than PAF. In contrast, LTD(4) increased both the R(pre) and R(post) to similar extent. U-46619 caused liver weight loss, while high concentrations of either LTD(4) or PAF produced liver weight gain, which was caused by substantial post-sinusoidal constriction and increased P(do). PAF and U-46619 decreased hepatic oxygen consumption while LTD(4) induced biphasic change of an initial transient decrease followed by an increase. In conclusion, PAF is the most potent vasoconstrictor of rat hepatic vessels among these three mediators. Both TxA(2) and PAF constrict the pre-sinusoidal veins predominantly. TxA(2) more preferentially constricts the pre-sinusoids than PAF, resulting in liver weight loss. However LTD(4) constricts both the pre- and post-sinusoidal veins similarly. High concentrations of LTD(4) and PAF cause liver weight gain by substantial post-sinusoidal constriction. PAF and TxA(2) decrease hepatic oxygen consumption, whereas LTD(4) causes a biphasic change of it.

The hepatic anaphylactic venoconstriction is partly involved in anaphylactic hypotension, and is characterized by significant post-sinusoidal constriction and liver congestion in guinea pigs. We determined what chemical mediators are involved in anaphylaxis-induced segmental venoconstriction and liver congestion in perfused livers isolated from ovalbumin sensitized guinea pigs. Livers were perfused portally and recirculatingly at constant flow with diluted blood. The sinusoidal pressure was measured by the double occlusion pressure (Pdo), and was used to determine the pre-sinusoidal (Rpre) and post-sinusoidal (Rpost) resistances. An antigen injection increased both the portal vein pressure and Pdo, resulting in 4.1- and 2.3-fold increases in Rpre and Rpost, respectively. Hepatic congestion was observed as reflected by liver weight gain. Pretreatment with TCV-309 (10microM, platelet-activating factor (PAF) receptor antagonist) or ONO-1078 (100microM, human cysteinyl-leukotriene (Cys-LT) receptor 1 antagonist), but not indomethacin (10microM, cyclooxygenase inhibitor), ketanserin (10microM, serotonin receptor antagonist), or diphenhydramine (100microM, histamine H1 antagonist), significantly attenuated this anaphylactic hepatic venoconstriction. Anaphylaxis-induced increases in Rpre and Rpost were significantly inhibited by TCV-309 (by 48%) and ONO-1078 (by 36%), respectively. Combined TCV-309 and ONO-1078 pretreatment exerted additive inhibitory effects on anaphylactic hepatic venoconstriction. Anaphylactic hepatic weight gain was converted to weight loss when post-sinusoidal constriction was attenuated. It is concluded that anaphylaxis-induced pre-sinusoidal constriction is mainly caused by PAF and the post-sinusoidal constriction by Cys-LTs in guinea pig livers.

Mice have frequently been used for a variety of physiological studies because of the development of genetic engineering. However, the characteristics of hepatic vessels such as the vascular resistance distribution and the reactivity to various vasoconstrictors are not known in mice. We therefore determined the basal levels of segmental vascular resistances and the effects of histamine and norepinephrine on the vascular resistance distribution of mice. The liver of male non-inbred ddY mice was excised and perfused via the portal vein with 5% bovine albumin-Krebs solution at a constant flow rate. The sinusoidal pressure was measured by the double occlusion pressure and used to determine the presinusoidal (R(pre)) and postsinusoidal (R(post)) resistances. The basal R(post) comprised 53 +/- 1% of the total hepatic vascular resistance. The norepinephrine and histamine increased R(pre) in a greater magnitude than R(post) with liver weight loss. However, the response to histamine was weaker than that to norepinephrine. Moreover, histamine-induced vasoconstriction showed tachyphylaxis. In conclusion, the presinusoidal and postsinusoidal resistances of mouse livers were similar in magnitude. The presinusoidal vessels predominantly contract in response to norepinephrine and histamine in mouse livers.

1. The role of shear stress in nitric oxide (NO)-mediated attenuation of anaphylactic venoconstriction was studied using an isolated ovalbumin-sensitized guinea pig liver. 2. Guinea pigs were actively sensitized by a subcutaneous injection of 1 mg ovalbumin. Two weeks after sensitization, the livers were perfused with diluted blood under constant flow or constant perfusion pressure. The constant flow could result in increased shear stress during constriction, while the constant perfusion pressure could prevent changes in shear stress. Using the double occlusion technique to estimate the hepatic sinusoidal pressure, pre- and postsinusoidal constriction was evaluated. Hepatic anaphylaxis was induced by an injection of ovalbumin (4 microg) into the perfusate, the volume of which was 40 mL. 3. Under either constant flow or pressure, anaphylaxis caused venoconstriction of predominantly presinusoids over postsinusoids, although anaphylactic venoconstriction under constant pressure was significantly greater than that under constant flow. When shear stress was held constant by maintaining constant perfusion pressure, a NO synthase inhibitor, Nomega-nitro-L-arginine methyl ester (L-NAME, 100 micromol/L), potentiated similarly both pre- and postsinusoidal constriction induced by anaphylaxis. This suggests that hepatic anaphylaxis shear stress-independently generates NO, resulting in dilatation of both pre- and postsinusoidal vessels in a similar magnitude. In contrast, when shear stress was allowed to rise under constant flow, anaphylactic presinusoidal constriction was preferentially potentiated by L-NAME. 4. Hepatic anaphylaxis can increase NO production in a shear stress-independent manner and dilates similarly both pre- and postsinusoids, while NO produced in a shear stress-dependent manner attenuates predominantly venoconstriction of the presinusoids where shear stress is preferentially increased.

Aim: Hepatic xenotransplantation from guinea-pig to rat has not been established. This failure is partly ascribed to differences in hepatic vascular characteristics between two species. However, the differences in hepatic vascular resistance distribution and responses to vasoconstrictors are not known. The present study was designed to determine basal levels of segmental vascular resistances and the responses to histamine and noradrenaline in isolated guinea-pig and rat livers., Methods: The livers were haemoperfused (Hct 8.3%) via the portal vein at a constant flow. The sinusoidal pressure was measured by the double occlusion pressure, and was used to determine the pre- (Rpre) and post-sinusoidal (Rpost) resistances., Results: There was no significant difference in basal total hepatic vascular resistance (Rt) between two species, whereas Rpre in rat (69% of Rt) was significantly greater than that in guinea-pig (61% of Rt). The responses to noradrenaline were similar; Rpre increased in a greater magnitude than Rpost, and liver weight was reduced. However, the noradrenaline-induced increase in Rt was greater in rats than in guinea-pigs. In contrast, histamine increased predominantly Rpost over Rpre, and increased liver weight in guinea-pig, while it affected no haemodynamic variables in rat., Conclusion: There exist species differences in the hepatic vasculature between rat and guinea-pig. Basal pre-sinusoidal resistance in rat is greater than that in guinea-pig. Although noradrenaline predominantly contracts pre-sinusoidal vessels in both species, histamine causes predominant post-sinusoidal vasoconstriction in guinea-pig liver, while it has no vasoactive effects on rat liver.

Lipid mediators, thromboxane A2 (TxA2) and platelet-activating factor (PAF), are potent vasoconstrictors, and have been implicated as mediators of liver diseases, such as ischemic-reperfusion injury. We determined the effects of a TxA2 analogue (U-46619) and PAF on the vascular resistance distribution and liver weight (wt) in isolated guinea pig livers perfused with blood via the portal vein. The sinusoidal pressure was measured by the double occlusion pressure (P(do)), and was used to determine the pre- (R(pre)) and post-sinusoidal (R(post)) resistances. U-46619 and PAF concentration-dependently increased the hepatic total vascular resistance (R(t)). The minimum concentration at which significant vasoconstriction occurs was 0.001 microM for PAF and 0.1 microM for U-46619. Moreover, the concentration of U-46619 required to increase R(t) to the same magnitude is 100 times higher than PAF. Thus, the responsiveness to PAF was greater than that to U-46619. Both agents increased predominantly R(pre) over R(post). U-46619 caused a sustained liver weight loss. In contrast, PAF also caused liver weight loss at lower concentrations, but it produced liver weight gain at higher concentrations (2.5 +/- 0.3 per 10g liver weight at 1 microM PAF), which was caused by substantial post-sinusoidal constriction and increased P(do). In conclusion, both TxA2 and PAF contract predominantly the pre-sinusoidal veins. TxA2 causes liver weight loss, while PAF at high concentrations increases liver weight due to substantial post-sinusoidal constriction in isolated guinea pig livers.

Liver biopsy based on a partial hepatectomy technique (shearing) was performed in 10 common marmosets (Callithrix jacchus). This is a preliminary study to evaluate the effects of drugs on hepatic microsomal enzymes: cytochrome P-450 and T4 uridine diphosphate glucuronyl transferase (T4-UDPGT), by comparing post-treatment values with pre-treatment values individually with a limited number of animals. The effects of the biopsy on clinical findings and liver pathology were evaluated during the first 5 post-surgical weeks. Although the plasma aspartate aminotransferase (AST) activities tended to decrease from 1 to 4 weeks post-surgery, no abnormality was noted in clinical sign, body weight, the hematocrit value or other blood chemical values. At necropsy, adhesion of the sheared site of the liver to the parietal peritoneum or the small intestine was evident in 2 of the 4 marmosets. Microscopic examination revealed focal fibrosis in the liver, but it was localized around the sheared site. Based on the above results, it was concluded that liver biopsy must be performed more than one month before administration of the drug to be tested. The biopsy samples and the whole liver samples obtained at autopsy were subjected to analysis of microsomal protein content, cytochrome P-450 content and T4-UDPGT activity. In comparison with the values from the whole liver samples, those from the biopsy samples showed no significant difference. Furthermore, there was a significant correlation rather than difference between matched values. This suggested that partial hepatectomy is a useful method for obtaining pretreatment values in liver biochemistry to evaluate the effects of drug-treatment in individual animals.

To evaluate the toxicological effect, di(2-ethylhexyl)phthalate (DEHP) was administered orally at 100, 500, and 2500 mg/kg to four male and four female marmosets in each group for 13 weeks. Its potentials of hepatic peroxisome proliferation, testicular atrophy, and pancreatic acinar cell hyperplasia were evaluated more closely. Clofibrate, which potently causes peroxisome proliferation in rodents, was administered in like manner at 250 mg/kg as a reference drug. DEHP induced significant suppression of weight gain in males at 2500 mg/kg. However, the increase in liver mass and hypertrophy of hepatocytes were not detected in organ weight measurements or histopathological examination. The number of peroxisomes, volume density, peroxisome morphology, and peroxisomal enzyme activities were not different from those in the control group, though the males treated with 500 and 2500 mg/kg DEHP showed 1.3- and 1.4-fold increases in mean peroxisome volume, respectively. In contrast, clofibrate induced 2.2 (in male)- and 1.9-fold (in female) increases in hepatic cyanide-insensitive acyl CoA oxidation system activity, 1. 2 (in male)- and 1.7-fold (in female) increases in hepatic carnitine-dependent acetyltransferase activity, and 1.8 (in male)- and 3.0-fold (in female) increases of carnitine-dependent palmitoyltransferase activity. Cytochrome P-450 contents tended to increase in all males and females administered 500 and 2500 mg/kg of DEHP and clofibrate associated with the increase in hepatic microsomal protein content, suggesting a relationship with the treatment. The atrophic change in the testis or proliferative change in the pancreatic acinar cells seen in rodents were not seen histopathologically; also, no changes were observed in testes weight, testicular zinc level, blood levels of testosterone and estradiol, pancreas weight, and blood levels of cholecystokinin. Finally, no changes considered to be due to the administration of DEHP were noted in blood chemical examination or pathological examination of other organs., (Copyright 1998 Academic Press.)

Four male and three female marmosets in each group were exposed to air only, 1000 ppm of HCFC 225ca or 5000 ppm of HCFC 225cb, for 6 h per day for 28 consecutive days. HCFC 225ca caused a slight reduction in body weight. HCFC 225cb occasionally caused somnolence during exposure and vomiting on the first day of exposure. Clinical chemistry findings included a mild reduction of triglyceride, cholesterol and phospholipid levels and increased GOT level in the HCFC 225ca exposure group. HCFC 225cb also caused a reduction of triglyceride levels in some animals. HCFC 225ca caused a slight increase of hepatic carnitine palmitoyltransferase (CPT) activity while HCFC 225cb slightly increased cyanide-insensitive palmitoyl CoA beta-oxidation (FAOS) activity. In the HCFC 225cb exposure group, an increase in cytochrome P-450 content was also observed. HCFC 225ca caused a fatty change in the hepatic cells. Increased incidence of lipid droplets in the hepatic cells and myelin-like bodies in hepatic cells, Kupffer's cells and hepatic blood vessels were observed electron microscopically in the HCFC 225ca exposure group. A proliferation of smooth endoplasmic reticulum was observed in the HCFC 225cb exposure group. Decreased peroxisome volume density in the HCFC 225ca group, and increased volume density in the HCFC 225cb exposed females were seen. However, organ weight measurement and histopathological examination did not reveal hepatomegaly or hypertrophy with either substance. Although slight changes were noticed in peroxisome volume density and in some of the peroxisomal enzyme activities, the changes related to peroxisome proliferation with HCFC 225ca and 225cb were minimal in marmosets compared to those seen in rats. Histopathological examination and hormonal analysis did not reveal any abnormalities in the pancreas or testes.

Exposure of agricultural workers and the general population to pesticides is a major concern, and possible summation or synergistic effects deserves particular attention. In this study, however, combined dietary administration of 19 organophosphorus compounds and one organochlorine pesticide, each at acceptable daily intake (ADI) levels, did not enhance rat liver preneoplastic lesion development initiated by diethylnitrosamine. In contrast, a mixture of 100 times ADI significantly increased the number and area of lesions. The results thus provide direct support for the present safety factor approach to the quantitative hazard evaluation of pesticides.

The fate of placental glutathione S-transferase (GST-P)-immunoreactive hepatocytes, detectable in livers of rats soon after treatment with N-nitrosodiethylamine (DEN), was examined sequentially with or without phenobarbital (PB) promotion. Group 1 male F344/NCr rats were administered a single i.p. injection of 200 mg DEN per kg body weight at 5 weeks of age. Group 2 rats were given 500 ppm PB in the diet two weeks after the DEN treatment. Groups of six rats were sequentially sacrificed 16, 42, 70, 126 and 238 days after DEN injection. In DEN-treated rats, GST-P immunoreactive hepatocytes (single cells and multiple cell foci) were detectable 16 days after DEN, the total numbers decreasing by day 70 and thereafter rising again. In the early stages the proportion of single immunoreactive hepatocytes was prominent, but with time a gradual increase in small GST-P+ hepatocellular foci and larger foci became evident. Feeding of PB to rats for 16-238 days after a single DEN injection resulted in increases of both single cells and foci, especially foci composed of more than three hepatocytes. The growth response was increasingly pronounced with time. Adenomas or carcinomas were only observed at 126 or 238 days. Numbers of GST-P+ foci far exceeded the numbers of foci visible in hematoxylin-eosin (H & E) stained sections, and a few H & E foci were negative for GST-P. Many GST-P+ foci smaller than ten cells were composed of histologically normal hepatocytes. Almost all GST-P+ foci identifiable in H&E stained sections were larger than ten cells, consisted of clear cells (in both groups) or mixed (clear-eosinophilic) cells in PB-exposed rats, and appeared to be evenly distributed throughout the three zones of the liver. These results suggest that the promotive effect of PB is most evident as an increase in larger hepatocyte populations composed of more than three GST-P+ hepatocytes, rather than in increasing the populations of single GST-P immunoreactive cells. PB may cause clonal expansion of these single GST-P reactive hepatocytes. This study provides evidence for the hypothesis that some of the GST-P reactive hepatocytes are initiated cells.

The modifying effects of harman or norharman on liver carcinogenesis were investigated in male F344/DuCrj rats initially treated with N-nitrosodiethylamine (DEN). Two weeks after a single dose of DEN (200 mg/kg, intraperitoneally), rats were given harman or norharman at dietary levels of 1000 and 200 parts per million (ppm), or sodium phenobarbital (PB) at 500 ppm as a positive control, for 6 wk. At wk 3 following DEN administration, all animals were subjected to partial hepatectomy. Marked retardation of body weight gain was observed in rats treated with harman or norharman at 1000 ppm, but not at 200 ppm. Increased relative kidney but not liver weights were associated with harman or norharman treatment, especially in the higher dose groups. Although no toxicity-related hepatocyte lesions were found, severe renal toxic tubular lesions and regeneration were evident. Neither harman nor norharman significantly increased the numbers or areas of glutathione S-transferase placental form (GST-P) positive foci observed after DEN initiation, in clear contrast to PB. The results thus demonstrated that harman and norharman are nontoxic for the liver and lack modifying potential for liver carcinogenesis in our medium-term bioassay system.

The initiating and promoting activities of several mycotoxins were investigated in F344 male rats. N-2-Fluorenylacetamide (2-FAA) was used as an initiator or a promoter and citrinin, ochratoxin A, sterigmatocystin, (+)rugulosin or patulin was administered at a fixed dose for the same period in the initiation stage or the promotion stage. Partial hepatectomy and administration of carbon tetrachloride (CCl4) were examined to increase the induction of hyperplastic nodules. Ochratoxin A, sterigmatocystin and (+)rugulosin administered in either the initiating or the promoting stage significantly increased the induction of hyperplastic nodules. Citrinin and patulin administered in the initiating stage significantly increased the induction of hyperplastic nodules, but were not effective when administered during the promoting stage. The theoretical classification of the mycotoxins examined is discussed.