Le syndrome hépatorénal chez le patient cirrhotique

Aerobic exercise training increases nitrergic innervation function and decreases sympathetic innervation function in mesenteric artery from rats fed a high-fat diet

INTRODUCTION

We investigated whether high-fat diet (HFD)-induced obesity was associated with modifications in mesenteric innervation function, the mechanisms involved, and the possible effects of aerobic exercise training on these changes.

MATERIALS AND METHODS

Male Wistar rats were divided into three groups: rats fed a standard diet (control group); rats fed a HFD (35% fat) for 8 weeks; and HFD rats submitted to aerobic exercise training (8 weeks, 5 times per week for 50  min). Segments of isolated mesenteric arteries were exposed to electric field stimulation (EFS) with or without phentolamine, suramin, or Nω nitro-L-arginine methyl ester. Noradrenaline, ATP, and nitric oxide release, and total and phosphorylated neuronal nitric oxide synthase (nNOS, P-nNOS) expression were also measured.

RESULTS

EFS contraction was greater in sedentary HFD than in control rats. Phentolamine reduced EFS contractions more markedly in HFD rats. Suramin decreased EFS contractions only in control rats. Phentolamine + suramin practically abolished EFS-induced contraction in control rats, whereas it did not modify it in the HFD rats. Noradrenaline release was greater and ATP was lower in HFD rats. Nω nitro-L-arginine methyl ester increased contractions to EFS only in segments from control rats. Nitric oxide release and nNOS and P-nNOS expressions were lower in arterial segments from HFD rats than from control rats. None of these changes in sedentary HFD rats was present in the trained HFD rats.

CONCLUSIONS

Enhanced sympathetic and diminished nitrergic components contributed to increased vasoconstrictor responses to EFS in sedentary HFD rats. All these changes were avoided by aerobic exercise training, suggesting that aerobic exercise could reduce peripheral vascular resistance in obesity.

Opposite effect of mast cell stabilizers ketotifen and tranilast on the vasoconstrictor response to electrical field stimulation in rat mesenteric artery

OBJECTIVES

We analyzed whether mast cell stabilization by either ketotifen or tranilast could alter either sympathetic or nitrergic innervation function in rat mesenteric arteries.

METHODS

Electrical field stimulation (EFS)-induced contraction was analyzed in mesenteric segments from 6-month-old Wistar rats in three experimental groups: control, 3-hour ketotifen incubated (0.1 αmol/L), and 3-hour tranilast incubated (0.1 mmol/L). To assess the possible participation of nitrergic or sympathetic innervation, EFS contraction was analyzed in the presence of non-selective nitric oxide synthase (NOS) inhibitor L-NAME (0.1 mmol/L), α-adrenergic receptor antagonist phentolamine (0.1 µmol/L), or the neurotoxin 6-hydroxydopamine (6-OHDA, 1.46 mmol/L). Nitric oxide (NO) and superoxide anion (O2.(-) levels were measured, as were vasomotor responses to noradrenaline (NA) and to NO donor DEA-NO, in the presence and absence of 0.1 mmol/L tempol. Phosphorylated neuronal NOS (P-nNOS) expression was also analyzed.

RESULTS

EFS-induced contraction was increased by ketotifen and decreased by tranilast. L-NAME increased the vasoconstrictor response to EFS only in control segments. The vasodilator response to DEA-NO was higher in ketotifen- and tranilast-incubated segments, while tempol increased vasodilator response to DEA-NO only in control segments. Both NO and O2(-) release, and P-nNOS expression were diminished by ketotifen and by tranilast treatment. The decrease in EFS-induced contraction produced by phentolamine was lower in tranilast-incubated segments. NA vasomotor response was decreased only by tranilast. The remnant vasoconstriction observed in control and ketotifen-incubated segments was abolished by 6-OHDA.

CONCLUSION

While both ketotifen and tranilast diminish nitrergic innervation function, only tranilast diminishes sympathetic innnervation function, thus they alter the vasoconstrictor response to EFS in opposing manners.

Focal ischemic necrosis in advanced biliary atresia cirrhosis

This report correlates the clinical and biological findings, liver hemodynamics and histological features of focal INL in an infant with BA cirrhosis. An eight month old boy with BA, with previous successful porto-enterostomy, was admitted with signs of cholangitis and ascites. He was treated with antibiotics and diuretics with subsequent clinical improvement. Eight days later, while being fed with hyper-osmolar milk, he became febrile again: ASAT/ALAT climbed (9000/2300 IU/L), liver function deteriorated. Infectious work-up was negative. Liver-ultrasound showed reversed portal flow and a negative arterial diastolic flow. The patient recovered within five days under supportive treatment. A similar event recurred five days later. INL was suspected and semi-urgent living-related liver transplantation was performed, with uneventful post-operative course. Histology of the explanted liver showed extensive foci of INL of different ages. This report illustrates how the association of reversed portal and arterial diastolic flows, with subsequent liver hypoperfusion, may repeatedly cause foci of INL in BA cirrhosis, and lead to rapid progression to liver failure. Because of precarious hepatic blood supply in such patients, close monitoring of portal and diastolic arterial flows is recommended.

Type I inositol 1, 4, 5-triphosphate receptors increase in kidney of mice with fulminant hepatic failure

AIM: To delineate the mechanisms of renal vasocon-striction in hepatorenal syndrome (HRS), we investigated the expression of typeIinositol 1, 4, 5-triphosphate receptors (IP₃RI) of kidney in mice with fulminant hepatic failure (FHF).

METHODS: FHF was induced by lipopolysaccharide (LPS) in D-galactosamine (GalN) sensitized BALB/c mice. There were 20 mice in normal saline (NS)-treated group, 20 mice in LPS-treated group, 20 mice in GalN-treated group, and 60 mice in GalN/LPS-treated group (FHF group). Liver and kidney tissues were obtained at 2, 6, and 9 h after administration. The liver and kidney specimens were stained with hematoxylin-eosin for studying morphological changes under light microscope. The expression of IP₃RIin kidney tissue was tested by immunohistochemistry, Western blot and reverse transcription (RT)-PCR.

RESULTS: Kidney tissues were morphologically normal at all time points in all groups. IP₃RIproteins were found localized in the plasma region of glomerular mesangial cells (GMC) and vascular smooth muscle cells (VSMC) in kidney by immunohistochemical staining. In kidney of mice with FHF at 6 h and 9 h IP₃RIstaining was up-regulated. Results from Western blot demonstrated consistent and significant increment of IP₃RIexpression in mice with FHF at 6 h and 9 h (t = 3.16, P < 0.05; t = 5.43, P < 0.01). Furthermore, we evaluated IP₃RImRNA expression by RT-PCR and observed marked up-regulation of IP₃RImRNA in FHF samples at 2 h, 6 h and 9 h compared to controls (t = 2.97, P < 0.05; t = 4.42, P < 0.01; t = 3.81, P < 0.01).

CONCLUSION: The expression of IP₃RIprotein increased in GMC and renal VSMC of mice with FHF, possibly caused by up-regulation of IP₃RImRNA.