Julius F.W. Baller

A NEW ANIMAL-MODEL FOR HUMAN PREECLAMPSIA - ULTRA-LOW-DOSE ENDOTOXIN INFUSION IN PREGNANT RATS

OBJECTIVEnAn animal model for preeclampsia was developed by means of an ultra-low-dose endotoxin infusion protocol in conscious pregnant rats.nnnSTUDY DESIGNnRats received a permanent jugular vein cannula on day 0 of pregnancy, through which endotoxin (1.0 micrograms/kg body weight) (n = 10) or saline solution (n = 6) was infused during 1 hour on day 14 of pregnancy. Blood pressure, albuminuria, and platelet counts were measured, and histopathologic studies was performed in these rats.nnnRESULTSnA significant increase of blood pressure (p < 0.05) and of urinary albumin excretion (p < 0.05) was observed in endotoxin-treated pregnant animals, in contrast to control pregnant rats receiving saline solution. Platelet coagulopathy was found and glomerular fibrinogen deposits could be detected only in the endotoxin-treated pregnant rats. In addition, the activity of the glomerular antithrombotic enzyme adenosine diphosphatase was decreased in endotoxin-treated pregnant rats compared with saline solution-treated pregnant rats.nnnCONCLUSIONnBecause histopathologic and clinical events in this model mimic predominant features of human preeclampsia, this model may enable further study into the pathophysiologic mechanisms of this complication of pregnancy.

Effects of bile salt flux variations on the expression of hepatic bile salt transporters in vivo in mice

BACKGROUND/AIMSnExpression of hepatic bile salt transporters is partly regulated by bile salts via activation of nuclear farnesoid X-activated receptor (Fxr). We investigated the physiological relevance of this regulation by evaluating transporter expression in mice experiencing different transhepatic bile salt fluxes.nnnMETHODSnBile salt flux was manipulated by dietary supplementation with taurocholate (0.5% w/w) or cholestyramine (2% w/w) or by disruption of the cholesterol 7alpha-hydroxylase-gene (Cyp7A(-/-) mice) leading to reduced bile salt pool size. Expression of hepatic transporters was assessed (polymerase chain reaction (PCR), immunoblotting, and immunohistochemistry).nnnRESULTSnBiliary bile salt secretion was increased (+350%) or decreased (-50%) after taurocholate or cholestyramine feeding, respectively, but plasma bile salt concentrations and hepatic Fxr expression were not affected. The bile salt uptake system Na(+)-taurocholate co-transporting polypeptide (Ntcp) and organic anion transporting polypeptide-1 (Oatp1) were down-regulated by taurocholate and not affected by cholestyramine feeding. Cyp7A(-/-) mice did not show altered Ntcp or Oatp1 expression. Canalicular bile salt export pump (Bsep) was up-regulated by 65% in taurocholate-fed mice, and slightly down-regulated in Cyp7A(-/-) mice.nnnCONCLUSIONSnLarge variations in hepatic bile salt flux have minor effects on expression of murine Ntcp and Bsep in vivo, suggesting that these transporters are abundantly expressed and able to accommodate a wide range of physiological bile salt fluxes.

Aspirin treatment of the low-dose-endotoxin-treated pregnant rat: pathophysiologic and immunohistologic aspects☆

In the present study, we evaluated the effect of low-dose aspirin (acetylsalicylic acid (ASA); 1.0 mg/kg daily) on blood pressure, albumin excretion, glomerular fibrinogen deposits, and glomerular (basement) membrane-bound adenosine diphosphatase (ecto-ADPase) activity, as well as on glomerular inflammation in pregnant rats infused with low-dose endotoxin (1.0 mg/kg). Rats (day 14 of pregnancy) were infused with endotoxin (ET rats) or saline (control rats) and received ASA in their drinking water. These rats were compared with non-ASA-treated rats. Blood pressure and albumin excretion were measured from day 15 to day 21, and glomerular fibrinogen and ecto-ADPase activity were measured at day 21. Glomerular inflammation was evaluated at various times after the start of the infusion. The results show that treatment with ASA had a significant beneficial effect on hypertension and inflammation induced by endotoxin in pregnant rats, whereas it reduced albumin excretion and glomerular fibrinogen deposits in some of the rats.

The role of transhepatic bile salt flux in the control of hepatic secretion of triacylglycerol-rich lipoproteins in vivo in rodents

Bile salts (BS) have been shown to suppress the secretion of very-low-density lipoprotein-triglyceride (VLDL-TG) in rat and human hepatocytes in vitro. In the present study, we investigated whether the transhepatic BS flux affects VLDL-TG concentration and hepatic VLDL-TG secretion in vivo. In rats, the transhepatic BS flux was quantitatively manipulated by 1-week chronic bile diversion (BD), followed by intraduodenal infusion with taurocholate (TC) or saline for 6 h. In mice, the transhepatic BS flux was manipulated by a 3-week dietary supplementation with TC (0.5 wt.%) or cholestyramine (2 wt.%). In rats, BD followed by saline or TC infusion did not affect plasma triacylglycerol (TG) concentration, hepatic TG production rate or VLDL lipid composition, compared to control rats. In mice supplemented for 3 weeks with TC or cholestyramine, the transhepatic BS flux was increased by 335% and decreased by 48%, respectively, compared to controls. Among the three experimental groups of mice, an inverse relationship between transhepatic BS flux and either plasma TG concentration (R(2)=0.89) or VLDL-TG production rate (R(2)=0.87) was observed, but differences were relatively small. Present data support the concept that BS can reduce VLDL-TG concentration and inhibit hepatic TG secretion in vivo; however, this occurs only at supraphysiological transhepatic BS fluxes in mice.

Pregnancy enhances the sensitivity of glomerular ecto-adenosine triphosphate-diphosphohydrolase to products of activated polymorphonuclear leukocytes

To test the hypothesis that pregnancy enhances the sensitivity of glomerular ecto-adenosine triphosphate-diphosphohydrolase to products of activated polymorphonuclear leukocytes, cryostat-cut kidney sections of pregnant and cycling rats were exposed to activated polymorphonuclear leukocytes and subsequently stained for ecto-adenosine triphosphate-diphosphohydrolase activity. The results show that the levels of ecto-adenosine triphosphate-diphosphohydrolase activity of pregnant rats showed a significantly greater decrease after incubation with activated polymorphonuclear leukocytes than did those of cycling rats.

Oxygen-dependent injury by a human plasma factor associated with minimal change disease.

Abstract. The mechanism by which a human plasma factor associated with proteinuria is able to cause experimental glomerular albumin leakage is unknown. This factor (called 100KF) is able to induce glomerular alterations in the rat kidney, similar to those seen in minimal change disease, including loss of glomerular sialoglycoproteins and decreased expression of glomerular ecto-ATPase. It was previously shown that 100KF is able to stimulate release of reactive oxygen species in inflammatory cells in vitro. This prompted us to test whether 100KF-induced injury is oxygen dependent. The expression of glomerular sialoglycoproteins and ecto-ATPase was evaluated by standard histochemistry and computerized image analysis and expressed in arbitrary units. Rat kidney sections were incubated with or without 100KF under normal or oxygen-poor, i.e., nitrogen, conditions, or with supplementation of superoxide dismutase (SOD, 100 U/ml). The effect of 100KF on glomerular ecto-ATPase was oxygen dependent (32.98±2.14 under air vs. 65.20±5.53 under nitrogen, P≤0.01), in contrast to the 100KF-induced loss of glomerular sialoglycoproteins that was not significantly altered under nitrogen (62.67±10.08 under air vs. 61.74±26.05 under nitrogen). Supplementation of SOD to 100KF solution under normal incubation conditions also suggested oxygen-dependent impairment of glomerular ecto-ATPase. Alternate perfusion ex vivo of the rat kidney with 100KF followed by diluted plasma showed that enhanced leakage of plasma proteins could be inhibited with SOD, indicating oxygen dependency of this 100KF-induced enhanced permeability (60.25±19.32 μg urinary albumin/ml after 100KF perfusion vs. 25.23±12.05 μg/ml after 100KF plus SOD, P≤0.01). We conclude that the action of 100KF upon specific glomerular matrix molecules is oxygen dependent, as is the albumin leakage induced by 100KF in the present ex vivo model.