The STUDIA UNIVERSITATIS BABEŞ-BOLYAI issue article summary

The summary of the selected article appears at the bottom of the page. In order to get back to the contents of the issue this article belongs to you have to access the link from the title. In order to see all the articles of the archive which have as author/co-author one of the authors mentioned below, you have to access the link from the author's name.

 
       
         
    STUDIA BIOLOGIA - Issue no. 1 / 2004  
         
  Article:   EFFECT OF ACUTE ENDOTOXIN ADMINISTRATION TO RATS ON MEMBRANE PERMEABILITY AND RELATED FUNCTIONAL PARAMETERS OF LIVER MITOCHONDRIA.

Authors:  CORNELIU TARBA, FELICIA SUĂRĂŞAN.
 
       
         
  Abstract:  __ Male white Wistar rats were maintained in our animal facility for 14-18 weeks and the evolution of their body weight was assessed periodically. 24 hrs before sacrificing, part of the control animals were injected with either 0.5 or 2 mg bacterial endotoxin/kg body weight. Another group of rats was chronically fed ethanol (1.5 ml of 48% alcohol/100 g body weight, daily) and some of these alcoholic rats also received 0.5 or 2 mg endotoxin/kg body weight 24 hrs prior to sacrifice. The liver of the animals was used for mitochondrial preparations and in some cases also for samples of electron microscopy. Mitochondrial membrane permeability was assessed indirectly from the matrix swelling in the presence of different concentrations of calcium. In addition, membrane potential (ΔΨ) and calcium fluxes were also monitored spectrophotometrically, as described in our previous paper (Tarba and Suărăşan [46]). The capacity of mitochondria to resist to different calcium loads was estimated qualitatively from such spectrophotometric recordings and also quantified by counting the number of calcium pulses (of 12.5 μM each) needed for the triggering of the permeability transition, ΔΨ collapse and calcium release. Predictably, all the phenomena tested occur faster (at shorter times and/or lower calcium concentrations) in ionic media, especially in those that lack magnesium. However, statistically, no significant differences were observed between the results obtained with the two doses of endotoxin. Also, a certain degree of similarity could be observed between the ethanol-fed and the endotoxin-treated rats. On the other hand, very significant differences were observed between the mitochondria of the endotoxin-treated rats (as a single group) and of the control rats. Thus, mitochondria from endotoxin-treated animals are more sensitive to calcium loads than those of the (non-alcoholic) control, they approaching the behaviour of the mitochondria from alcohol-fed rats, although the sensitivity to calcium is somewhat lower. This lower sensitivity can be seen in ionic media, especially in the swelling medium (KSW), where the differences are highly significant (p<0.001). The mitochondria of double-treated animals (endotoxin-injected alcohol-fed rats) show a more complex behaviour and less homogeneity. Their sensitivity to metabolic stress is in general higher than that of the simply endotoxin-treated animals, but comparable to that of the simply ethanol-fed rats, although in ionic suspending media membrane permeability actually tends to be lower, a fact that must be attributed to the endotoxin treatment. A certain degree of dissociation of the ΔΨ collapse from the matrix swelling and calcium release was also observed. The fact that ΔΨ collapse occurs apparently at a later time than the matrix swelling and calcium release is interpreted by us as an indication of a differential sensitivity of different types of hepatic mitochondria to the metabolic stress factors, such as chronic ethanol feeding and acute LPS administration.  
         
     
         
         
      Back to previous page