Taurine supplementation induces multidrug resistance protein 2 and bile salt export pump expression in rats and prevents endotoxin-induced cholestasis

The effect of oral taurine supplementation on endotoxin-induced cholestasis was investigated in rat liver. At 12h following lipopolysaccharide (LPS) injection (4mg/kg body weight i.p.) bile flow and bromosulfophthalein (BSP) and taurocholate (TC) excretion were determined in the perfused liver and the expression of the canalicular transporters multidrug resistance protein 2 (Mrp2) and bile salt export pump (Bsep) was analyzed. Injection of LPS induced a significant decrease of bile flow ( 2.2+/-0.2 microl/g liver wet weight/min vs 3.3+/-0.1 microl/g liver wet weight in controls), biliary BSP excretion (10.8+/-2.2 nmol/g/min vs 21.0+/-3.8 nmol/g/min), and biliary TC excretion (114+/-23 nmol/g/min vs 228+/-8 nmol/g/min). These effects were due to transporter retrieval from the canalicular membrane and downregulation of Mrp2 and Bsep expression. In taurine-supplemented rats bile flow was 30% higher than that in untreated rats and the expression of Mrp2 and Bsep protein was increased two- to threefold. In taurine-supplemented rats there was no significant reduction of bile flow or of BSP and TC excretion at 12h following LPS injection. This protective effect of taurine was due to higher Mrp2 and Bsep protein levels compared to nonsupplemented LPS-treated rats, whereas relative Mrp2 retrieval from the canalicular membrane induced by LPS was not significantly different. LPS-induced tumor necrosis factor alpha and interleukin-1beta release were lower in taurine-fed rats; however, downregulation of Mrp2 and Bsep expression by LPS was delayed but not prevented. The data show that oral supplementation of taurine induces Mrp2 and Bsep expression and may prevent LPS-induced cholestasis.     

Surplus acylcarnitines in the plasma of starved rats derive from the liver

The method used here to assess the contribution of liver to plasma acylcarnitine is based on the idea that in rat, shortly after administration of [3H]butyrobetaine the [3H]carnitine appearing in the plasma derives from the liver and so does the acyl moiety of [acyl-3H] carnitine. In the perchloric acid extracts of plasma and liver, the ester fraction of total carnitine was determined by enzymatic analysis and that of [3H]carnitines was determined by high performance liquid chromatography. The ester fraction of total carnitine in the plasma of fed rats was 32.6% while that of [3H]carnitines was 67.9%, 1 h following injection of [3H]butyrobetaine. For 48 h starved rats the equivalent values were 54.2 and 84.0%, respectively. 24 h after the administration of [3H]butyrobetaine, the ester content became the same in the total and [3H]carnitines. That the newly synthesized carnitine was more acylated (67.9 versus 32.6%, fed) indicates that liver exports acyl groups with carnitine as carrier. The observation that the ester fraction in the newly synthesized plasma carnitine increased with fasting (84.0 versus 67.9%) indicates that the surplus plasma acylcarnitine in fasting ketosis derives from the liver. Perfused livers, however, released carnitine with the same ester content (60-61%) whether they were from fed or fasted animals. Probably, the increased plasma [acylcarnitine] in fasting develops not by an increased ester output from the liver but by an altered handling in extrahepatic tissues.     

Butyrobetaine availability in liver is a regulatory factor for carnitine biosynthesis in rat. Flux through butyrobetaine hydroxylase in fasting state

Urinary excretion of total carnitine in 48-h fasted rats dropped to 0.30 +/- 0.01 mumol/day from 2.23 +/- 0.4 mumol/day found in fed, control animals (mean +/- SEM). Despite this marked retention, the total carnitine content of the whole body remained constant, about 83 mumol, predicting a slow-down in biosynthesis. The conversion of butyrobetaine into carnitine takes place only in the liver in rats. 48 h of starvation caused a decrease in the liver butyrobetaine level from 11.6 +/- 1.19 nmol/g to 9.30 +/- 1.19 nmol/g, which in whole livers corresponds to a decrease from 138 nmol to 61.3 nmol. The conversion rate of butyrobetaine into carnitine was studied with radiolabelled butyrobetaine. 30 min after injection of [3H]butyrobetaine the carnitine pool in the liver of fasted rats was labelled to about the same extent as that in fed rats, but from a butyrobetaine pool with higher specific radioactivity. Therefore, the conversion rate of butyrobetaine into carnitine was reduced. The newly formed carnitine found in the whole body of fasted rats was estimated to be 59% of controls. We conclude that the biosynthesis of carnitine in fasted rats slows down, for which a decreased availability of butyrobetaine in the liver is responsible. Urinary excretion of butyrobetaine in the fasted group decreased to 74.1 nmol/day from the 222-nmol/day control value while the butyrobetaine content of whole body did not significantly decrease (2.85 mumol vs. 3.04 mumol). Urinary excretion of trimethyllysine was also depressed.     

Thromboxane A2 from Kupffer cells contributes to the hyperresponsiveness of hepatic portal circulation to endothelin-1 in endotoxemic rats

We examined the role of thromboxane A2 (TXA2) in LPS-induced hyperresponsiveness of hepatic portal circulation to endothelins (ETs) and whether Kupffer cells are the primary source of TXA2 release in response to ET-1 in endotoxemia. After 6 h of LPS (1 mg/kg body wt ip) or saline (control), liver was isolated and perfused with recirculating Krebs-Henseleit bicarbonate buffer at a constant flow rate (100 ml.min(-1).kg body wt(-1)). ET-1 (10 pmol/min) was infused for 10 min. Portal pressure (PP) was continuously monitored during perfusion. Perfusate was sampled for enzyme immunoassay of thromboxane B2 (TXB2; the stable metabolite of TXA2) and lactate dehydrogenase (LDH) assay. ET-1 infusion resulted in a significantly greater increase of PP in the LPS group than in controls. Both TXA2 synthase inhibitor furegrelate (Fureg) and TXA2 receptor antagonist SQ-29548 (SQ) substantially blocked enhanced increase of PP in the LPS group (4.9 +/- 0.4 vs. 3.6 +/- 0.5 vs. 2.6 +/- 0.6 mmHg for LPS alone, LPS + Fureg, and LPS + SQ, respectively; P < 0.05) while having no significant effect on controls. GdCl3 for inhibition of Kupffer cells had similar effects (4.9 +/- 0.4 mmHg vs. 2.9 +/- 0.4 mmHg for LPS alone and GdCl3 + LPS, respectively; P < 0.05). In addition, the attenuated PP after ET-1 was found concomitantly with significantly decreased releases of TXB2 and LDH in LPS rats treated with Fureg, SQ, and GdCl3 (886.6 +/- 73.4 vs. 110.8 +/- 0.8 vs. 114.8 +/- 54.7 vs. 135.2 +/- 45.2 pg/ml, respectively; P < 0.05). After 6 h of LPS, Kupffer cells in isolated cell preparations released a significant amount of TXA2 in response to ET-1. These results clearly indicate that hyperresponsiveness of hepatic portal circulation to ET-1 in endotoxemia is mediated at least in part by TXA2-induced receptor activation, and Kupffer cells are likely the primary source of increased TXA2 release.     

Increased formation of S-nitrothiols and nitrotyrosine in cirrhotic rats during endotoxemia

Plasma S-nitrosothiols are believed to function as a circulating form of nitric oxide that affects both vascular function and platelet aggregation. However, the formation of circulating S-nitrosothiols in relation to acute and chronic disease is largely unknown. Plasma S-nitrosothiols were measured by chemiluminescence in rats with biliary cirrhosis or controls, and the effect of lipopolysaccharide (LPS) on their formation was determined. Plasma S-nitrosothiols were increased in rats with cirrhosis (206 +/- 59 nM) compared to controls (51 +/- 6 nM, p <.001). Two hours following injection of LPS (0.5 mg/kg) plasma S-nitrosothiols increased to 108 +/- 23 nM in controls (p <.01) and to 1335 +/- 423 nM in cirrhotic rats (p <.001). The plasma clearance and half-life of S-nitrosoalbumin, the predominant circulating S-nitrosothiol, were similar in control and cirrhotic rats, confirming that the increased plasma concentrations were due to increased synthesis. Because reactive nitrogen species, such as peroxynitrite, may cause the formation of S-nitrosothiols in vivo, we determined the levels of nitrotyrosine by gas chromatography/mass spectrometry as an index for these nitrating and nitrosating radicals. Hepatic nitrotyrosine levels were increased at 7.0 +/- 1.2 ng/mg in cirrhotic rats compared to controls (2.0 +/- 0.2 ng/mg, p <.01). Hepatic nitrotyrosine levels increased by 2.3-fold and 1.5-fold in control and cirrhotic rats, respectively, at 2 h following injection of LPS (p <.01). Strong positive staining for nitrotyrosine was shown by immunohistochemistry in all the livers of the rats with cirrhosis. We conclude that there is increased formation of S-nitrosothiols and nitrotyrosine in biliary cirrhosis, and this is markedly upregulated during endotoxemia.     

Liver denervation affects hepatocyte mitochondrial fatty acid transport capacity

The effect of liver denervation on the activity of hepatic carnitine palmitoyltransferase (CPT) system, which catalyses the transfer of long-chain fatty acids into the mitochondria, was studied in rats. Noradrenaline content in phenol-denervated liver (D) was reduced by 87%. CPT I and II activities (measured by radioassay after detergent separation of the enzymes) were decreased (p < 0.001) in D (2.6 +/- 0.1 and 0.68 +/- 0.2 nmol min(-1) mg(-1) protein, respectively) as compared with controls (4.7 +/- 0.3 and 2.5 +/- 0.2 nmol min(-1) mg(-1) protein, for CPT I and II, respectively). A less intense immunoreactive band for denervated liver CPT II was obtained after Western blotting. Concomitantly, long-chain fatty acid incorporation (p < 0.001), evaluated after administration of [14C]-oleate and total fat content (p < 0.001) were increased in D in relation to controls, while incorporation of exogenous [14C]-oleate into secreted VLDL, was decreased (p < 0.01). The effect of sympathetic denervation on CPT activity was different from that evoked by adrenodemedullation, which caused an augmentation of CPT activity (p < 0.01), when compared with the liver of intact rats. The effects of denervation and adrenodemedullation on the other parameters of lipid metabolism studied, were similar. The results strongly suggest a role of liver sympathetic innervation in the regulation of liver lipid metabolism.     

High hemoglobin affinity to oxygen and its relationships with lipid peroxidation during fever

The effects of high hemoglobin-oxygen affinity (HOA) on rectal temperature and lipid free radical oxidation were investigated in red blood cells, heart, liver and kidneys of male rats during fever. Fever was induced by intraperitoneal injection of Salmonella typhi lipopolysaccharide (LPS; 5.0 mg kg(-1)). HOA was increased by addition of 0.5% sodium cyanate to drinking water for eight weeks. HOA modification (actual half-saturation oxygen pressure, P50act, decreased to 23.3+/-0.7 vs. 31.6+/-0.7 Torr in control; p < 0.001) weakened a febrile response: rise of temperature after 4 hours was 0.79+/-0.2 degrees C vs. 1.38+/-0.1 degrees C in rats with normal HOA (p < 0.05). In red cells and tissues of rats with normal HOA, concentrations of conjugated dienes and Schiff bases increased during fever, and alpha-tocopherol level and catalase activity decreased. Rats with increased HOA had an inverse pattern of such changes. Changes in rectal temperature and markers of free radical oxidation correlated with a shift of oxyhemoglobin dissociation curve leftwards. The present results indicate that the intentional increment of HOA may substantially diminish lipid peroxidation activity, increase the body antioxidant content during fever and decrease the febrile response on LPS.     

Malonyl-CoA in skeletal muscle and liver of streptozotocin-diabetic rats.

Malonyl-CoA, the inhibitor of carnitine palmitoyl transferase I, has been examined in this study in the muscle and liver of diabetic rats. Male Sprague-Dawley rats were rendered diabetic with streptozotocin (6 mg/100 g body wt). The gastrocnemius/plantaris muscles and liver samples were frozen at liquid nitrogen temperature. Muscle malonyl-CoA was 1.8 +/- 0.2 pmol/mg in control rats and 1.5 +/- 0.2 pmol/mg in the diabetic rats. This difference was not statistically significant. Liver malonyl-CoA of control rats was 8.6 +/- 0.8 pmol/mg, in comparison to 4.3 +/- 0.6 pmol/mg in diabetic rats. In the liver, high concentrations of malonyl-CoA inhibit fatty acid oxidation and ketogenesis. Failure of malonyl-CoA to decline in muscle in the diabetic may be responsible in part for the diversion of fatty acids to the liver, thereby enhancing hepatic fatty acid oxidation and ketogenesis.     

Angiopoietin-1 increases arteriolar vasoconstriction to phenylephrine during sepsis

Sepsis leads to a reduction in vascular tone and a loss of vasoconstriction in response to catecholamines. We propose that angiopoietin-1 (Ang-1), which is known to modulate vascular inflammation and nitric oxide (NO), could improve responsiveness to vasopressor agents during sepsis. Mesenteric arterioles (300-400 microm) from rats (n=19) were mounted in a pressurized myograph and incubated with lipopolysaccharide (LPS, 50 microg/mL) for up to 4 h to model sepsis. Vasoconstriction (mean+/-SD) to phenylephrine (10(-8)-10(-3) M) was reduced in the presence of LPS (4 h, pD2: 5.8+/-0.2 (controls, n=6), 1.4+/-2.2 (LPS, n=6); maximal constriction: 48.2+/-4.8% (controls), 2.6+/-5.8% (LPS), P<0.05). However, in the presence of Ang-1 (250 ng/mL) phenylephrine caused greater vasoconstriction compared to LPS alone (4 h, pD2: 4.5+/-2.1; maximal constriction: 12.6+/-4.0% (n=7), P<0.05). In conclusion, Ang-1 increases vasoconstriction to phenylephrine in the presence of LPS. During sepsis therefore, Ang-1 increases vascular reactivity and has the potential to increase blood pressure and decrease vasopressor requirements in vivo.     

Intestinal absorption and postabsorptive metabolism of linoleic acid in rats with short-term bile duct ligation

We investigated in bile duct-ligated (BDL) and sham-operated control rats whether the frequent presence of essential fatty acid deficiency in cholestatic liver disease could be related to linoleic acid malabsorption, altered linoleic acid metabolism, or both. In plasma of BDL rats, the triene-to-tetraene ratio, a biochemical marker for essential fatty acid deficiency, was increased compared with controls (0.024 +/- 0.004 vs. 0.013 +/- 0.001; P < 0.05). Net and percentage of dietary linoleic acid absorbed were decreased in BDL rats compared with control rats (1.50 +/- 0.16 mmol/day and 81.3 +/- 3.3% vs. 2.08 +/- 0.07 mmol/day and 99.2 +/- 0.1%, respectively; each P < 0.001). At 24 h after [(13)C]linoleic acid administration, BDL rats had a similar ratio of plasma [(13)C]arachidonic acid to plasma [(13)C]linoleic acid concentration compared with control rats. Delta(6)-Desaturase activity was not significantly different in hepatic microsomes from control or BDL rats. At 3 h after [(13)C]linoleic acid administration, plasma appearance of [(13)C]linoleic acid and cumulative expiration of (13)CO(2) were decreased in BDL rats, compared with controls (by 54% and 80%, respectively). The present data indicate that the impaired linoleic acid status in cholestatic liver disease is mainly due to decreased net absorption and not to quantitative alterations in postabsorptive metabolism.     

Muscle malonyl-CoA decreases during exercise

Malonyl-CoA, the inhibitor of carnitine acyltransferase I, is an important regulator of fatty acid oxidation and ketogenesis in the liver. Muscle carnitine acyltransferase I has previously been reported to be more sensitive to malonyl-CoA inhibition than is liver carnitine acyltransferase I. Fluctuations in malonyl-CoA concentration may therefore be important in regulating the rate of fatty acid oxidation in muscle during exercise. Male rats were anesthetized (pentobarbital via venous catheters) at rest or after 30 min of treadmill exercise (21 m/min, 15% grade). The gastrocnemius/plantaris muscles were frozen at liquid N2 temperature. Muscle malonyl-CoA decreased from 1.66 +/- 0.17 to 0.60 +/- 0.05 nmol/g during the exercise. This change was accompanied by a 31% increase in cAMP in the muscle. The decline in malonyl-CoA occurred before muscle glycogen depletion and before onset of hypoglycemia. Plasma catecholamines, corticosterone, and free fatty acids were all significantly increased during the exercise. This exercise-induced decrease in malonyl-CoA may be important for allowing the increase in muscle fatty acid oxidation during exercise.     

Altered glucose transporter mRNA abundance in a rat model of endotoxic shock

To better understand molecular mechanisms of glucose transport in shock, we studied glucose transporter isoform mRNA abundance after injection of S. enteritidis endotoxin (40 mg/kg) or saline. Six to 8 hours after injection, endotoxin-treated animals compared to controls became hypoglycemic (44 +/- 6 vs. 111 +/- 4 mg/dl) and lactacidemic (5.9 +/- 0.5 vs. 1.3 +/- 0.1). At such times, tissue RNA was isolated and hybridized to Riboprobes for GLUT1 (erythrocyte), GLUT2 (liver), and GLUT4 (muscle/fat) glucose transporter isoforms and expressed as percent of control. GLUT1 mRNA abundance was increased in fat (660%, p less than .05), soleus muscle (314%, p less than .05), and liver (871%, p less than .001) of endotoxin-treated rats. Soleus muscle GLUT4 mRNA levels were increased (+33%, p less than .02), while liver GLUT2 mRNA levels were markedly decreased (-58%, p less than .01). The overall increase in GLUT1 mRNA abundance accompanied by lowered liver GLUT2 mRNA levels may either cause or reflect profoundly altered glucose transport.     

内源性硫化氢在脂多糖引起的肺动脉高压中的作用

为观察硫化氢(hydrogen sulfide,H2s)在脂多糖(1ipopolysaccharide,LPS)引起的肺动脉高压中的作用,应用离体血管环张力测定方法测定肺动脉反应性,采用生物化学方法测定肺动脉组织中H2S产出率和胱硫醚-γ-裂解酶(cystathionine γ-lyase,CSE)活性,定量PCR方法测定肺动脉组织中CSE表达水平.结果如下:(1)与对照组相比,LPS可显著升高肺动脉平均压(mean pulmonary arterial pressure,mPAP)[(1.82±0.29)kPa vs(1.43±0.26)kPa,P<0.01],降低肺动脉组织中H2S产出率[(26.33±7.84)vs(42.92±8.73)pmoFg wet tissue per minute,P<0.01]和ACh诱导的肺动脉内皮依赖性舒张反应[(75.72±7.22)%vs(86.40±4.40)%,P<0.01];(2)NariS可部分逆转上述变化,而PPG加剧上述变化;(3)CSE活性和CSE mRNA表达的变化与H2S产出率的变化相同.结果提示,LPS对内皮依赖性舒张反应的抑制导致肺动脉高压的发生,此作用可能与H2S有关.     

Plasma and urinary levels of carnitine in different experimental models of hyperammonemia and the effect of sodium benzoate treatment

The effect of hyperammonemia on plasma and urinary levels of carnitine was studied in different groups of +/Y (normal) and spf/Y (chronically hyperammonemic) mice. Experimental models of acute and subacute hyperammonemia were prepared in +/Y and spf/Y mice by the use of ammonium acetate ip injections and arginine-free diets, respectively. In acute hyperammonemia, the plasma levels of both free and acylcarnitines increased significantly whereas acyl/free carnitine ratio was decreased, indicating a mobilization of carnitine from the storage sites. The subacute hyperammonemia model showed the same tendency in respect of plasma and urinary carnitines; however, the values in plasma were more significantly different. The effect of sodium benzoate on plasma carnitine levels, during both an acute and a prolonged treatment, consisted in a significant lowering of free carnitine and a significant increase in the acyl/free carnitine ratio, in both +/Y normal and spf/Y mouse models. The changes in the urinary profile, on benzoate treatments, were not significant. These results demonstrate the individual effects of hyperammonemia and benzoate therapy on carnitine metabolism, which may be helpful in understanding and ameliorating the therapeutic approach to hereditary hyperammonemias.     

Bile acid secretion and pool size during phenobarbital induced hypercholeresis

An increase in bile flow after phenobarbital administration occurs in the rat and other species; however, the mechanism(s) of the choleretic effect is incompletely understood and the role of the increase in liver weight is controversial. We therefore measured bile flow, bile acid secretion and pool size in male Sprague-Dawley rats pretreated with phenobarbital (75 mg/kg/day) for 6 days; liver weight, liver cell volume and DNA content were also evaluated. Phenobarbital treatment increased liver weight and mean hepatocyte volume by 39 and 26%, respectively, while total DNA content did not change, thus indicating that the hepatomegaly results principally from hypertrophy rather than hyperplasia. Bile flow was significantly higher in treated rats when expressed per unit of body weight (64.6 +/- 2.4 (S.E.) vs 53.3 +/- 1.6 microliter/min/kg; P less than 0.05) but was unchanged when expressed per gram of liver (1.40 +/- 0.04 vs 1.37 +/- 0.06 microliter/min/g; P greater than 0.5). The initial bile acid secretion rate and pool size were both significantly reduced in the phenobarbital group compared to controls (1224.2 +/- 110.4 vs 1656.6 +/- 163.2 nmol/kg/min and 562.8 +/- 41.5 vs 814.3 +/- 78.3 mumol/kg; both P less than 0.05), whereas the basal synthetic rate was unchanged. These findings suggest that the enlarged, phenobarbital-treated hepatocyte produces more bile than the normal cell, despite the decreased secretion of bile acids. Therefore, the drug-induced choleresis involves a selective increase in the bile acid-independent fraction of bile flow.     

Arginine and glutamine availability and macrophage functions in the obese insulin-resistant Zucker rat

Increased susceptibility to infections in obese patients may be related to decreased availability of arginine and glutamine, which may affect immune cell functions. Our aim was to evaluate the in vitro effects of these amino acids on the function of macrophages from obese insulin-resistant Zucker rats. Macrophages, isolated from male Zucker obese or lean rats by peritoneal lavage, were incubated in Dulbecco's modified Eagle medium (DMEM) without arginine or glutamine. Arginine or glutamine was added to the medium at increasing final concentrations (0, 0.25, 0.5, 1 or 2 mM). After stimulation by lipopolysaccharide (LPS) from E. coli (40 microg/ml), productions of tumour necrosis factor alpha (TNFalpha) and of nitric oxide (NO) were measured after 3 or 48 h incubation, respectively. NO production, lower in macrophages from obese rats, decreased in macrophages from lean rats (0 mM: 2,423 +/- 1,174 vs. 2 mM: 198 +/- 31 microM/mg protein/24 h; P < 0.05), but not in those from obese rats, when glutamine was added. TNFalpha production, lower in macrophages from obese rats, was inversely correlated with glutamine concentration. In the presence of arginine, NO production was constantly higher in macrophages from obese rats. It peaked at 0.5 mM arginine and decreased thereafter in both groups. TNFalpha production in macrophages from lean rats was unaffected by arginine, but decreased in macrophages from obese rats (0 mM: 1920 +/- 450 vs. 2 mM: 810 +/- 90 microM/mg protein/3 h; P < 0.05). These results suggest that abnormalities in cell signalling or in arginine and glutamine metabolism in macrophages of obese rats, resulting in decreased TNFalpha production and increased NO release, may contribute to increased susceptibility to infection in insulin-resistant states.     

Parthenolide has limited effects on nuclear factor-kappa beta increases and worsens survival in lipopolysaccharide-challenged C57BL/6J mice

Parthenolide, a sesquiterpene lactone, inhibited lipopolysaccharide (LPS) stimulated nuclear factor (NF)-kappabeta and cytokine production in vitro and in rats, and improved survival in LPS challenged Swiss albino mice. We investigated whether increased survival with parthenolide was associated directly with inhibition of NF-kappabeta and cytokines in LPS challenged C57BL/6J mice. In RAW 264.7 cells, parthenolide inhibited LPS-stimulated NF-kappabeta and cytokines (interleukin [IL]-1alpha, -1beta, -2, -4, -6, and -10, interferon-gamma, tumor necrosis factor-alpha, granulocyte macrophage-colony stimulating factor, migratory inhibitory protein-1 and -2alpha, JE, and RANTES). In mice (n = 366) receiving lethal intraperitoneal (i.p.) LPS (40 mg/kg), compared to placebo, each of 5 parthenolide doses (0.25 to 4 mg/kg i.p. following LPS) reduced survival at 168h and overall worsened the hazards ratio of survival (mean +/- S.E.M.) (1.29 +/- 0.12, p = 0.04). In other mice (241), compared to saline challenge, nonlethal LPS (2.5 mg/kg) increased NF-kappabeta in lung and kidney combined and 12 of 13 plasma cytokines early (1 and 3 h) and late (6, 9 and 12 h) (p < or = 0.002 for each). Compared to nonlethal LPS, lethal LPS increased NF-kappabeta and 12 of 13 cytokines early but not significantly and late significantly (p < or = 0.05 for each). With lethal LPS, compared to placebo, parthenolide (1 mg/kg) decreased NF-kappabeta and 10 of 13 cytokines early and increased NF-kappabeta and 11 of 13 cytokines late (p < or = 0.02 for early vs. late). Although parthenolide inhibits NF-kappabeta and cytokines in vitro, its effects on these mediators and survival in animal sepsis models vary. Theses differences must be understood before parthenolide or related agents are applied clinically for sepsis.     

Regulation of lipid flux between liver and adipose tissue during transient hepatic steatosis in carnitine-depleted rats

Rats with carnitine deficiency due to trimethylhydrazinium propionate (mildronate) administered at 80 mg/100 g body weight per day for 10 days developed liver steatosis only upon fasting. This study aimed to determine whether the transient steatosis resulted from triglyceride accumulation due to the amount of fatty acids preserved through impaired fatty acid oxidation and/or from up-regulation of lipid exchange between liver and adipose tissue. In liver, mildronate decreased the carnitine content by approximately 13-fold and, in fasted rats, lowered the palmitate oxidation rate by 50% in the perfused organ, increased 9-fold the triglyceride content, and doubled the hepatic very low density lipoprotein secretion rate. Concomitantly, triglyceridemia was 13-fold greater than in controls. Hepatic carnitine palmitoyltransferase I activity and palmitate oxidation capacities measured in vitro were increased after treatment. Gene expression of hepatic proteins involved in fatty acid oxidation, triglyceride formation, and lipid uptake were all increased and were associated with increased hepatic free fatty acid content in treated rats. In periepididymal adipose tissue, mildronate markedly increased lipoprotein lipase and hormone-sensitive lipase activities in fed and fasted rats, respectively. On refeeding, carnitine-depleted rats exhibited a rapid decrease in blood triglycerides and free fatty acids, then after approximately 2 h, a marked drop of liver triglycerides and a progressive decrease in liver free fatty acids. Data show that up-regulation of liver activities, peripheral lipolysis, and lipoprotein lipase activity were likely essential factors for excess fat deposit and release alternately occurring in liver and adipose tissue of carnitine-depleted rats during the fed/fasted transition.     

Ganglioside treatment of diabetic rats; effects on nerve adenosine triphosphatase activity and motor nerve conduction velocity

Ouabain-sensitive ATPase activity (expressed as nmol ADP produced/h/mg (wet) nerve +/- SEM) was measured in homogenates of sciatic nerve from control rats and rats with streptozotocin-induced diabetes of 8 wk duration. Nerves from diabetic rats showed activity (21.7 +/- 2.0) which was significantly (p less than 0.05) less than that of controls (34.6 +/- 4.8). These animals also showed a deficit in conduction velocity (m/sec +/- SEM) of sciatic nerve motoneurones (50.7 +/- 0.4 vs. 57.7 +/- 0.7 in controls; p less than 0.001). In parallel, matched control and diabetic groups were treated daily with mixed gangliosides extracted from bovine brain (10 mg/kg i.p.). After such treatment for 8 wk the deficit in ouabain-sensitive ATPase activity did not develop in the diabetic group (treated diabetics, 31.9 +/- 3.7; treated controls, 34.5 +/- 3.8). However, the treatment did not affect the deficit in motor nerve conduction velocity (treated diabetics, 50.9 +/- 1.1 vs. treated controls, 57.9 +/- 0.5; p less than 0.001). Accumulations of the polyol pathway metabolites--sorbitol and fructose--together with depletion of nerve myo-inositol were similar in both diabetic groups. These data indicate an etiology for the conduction velocity deficit which differs from that of the deficit in ouabain-sensitive ATPase.