ABSTRACT
BACKGROUND: Ischemia-reperfusion injury caused by severe hemorrhagic shock and subsequent resuscitation leads to deterioration of hepatic homeostasis and possibly to liver failure. The present study focuses on determining whether there is a different biological response to hemorrhagic shock by different sources of hemorrhage, hepatic hemorrhage (HH) versus peripheral hemorrhage. METHODS: Twenty-one male swine (Sus scrofa domesticus) were randomly allocated in three groups as follows: sham group (S, n = 5), central venous hemorrhage group, (CVH) (n = 8), and HH group (n = 8). Hepatectomy of the left liver lobe was carried out in groups CVH and HH, and the animals were subjected to controlled bleeding from the internal jugular vein and the traumatic liver surface, respectively. After 10 min of hemorrhage, shock was maintained for 30 min at mean arterial pressure levels of 30 mm Hg-40 mm Hg and resuscitation was initiated with crystalloids and colloids. Hemodynamic parameters and fluid balance were monitored throughout the 6 h of total duration of the experiment. Blood samples were collected at 0-, 40-, and 360-min time points for transaminases, albumin, and interleukin-6 measurement. Hepatic tissue was harvested at the end of the experiment for oxidative marker and proliferation analysis. RESULTS: Although blood loss was comparable between the two groups, the amount of fluids needed for resuscitation was higher for the HH group. Inflammatory response, measured by interleukin-6, was found higher in HH group. Oxidative stress markers did not reveal statistically significant difference between the two groups. Liver hemorrhage decreased hepatocellular proliferation measured by proliferating cell nuclear antigen. CONCLUSIONS: Our study provides evidence that HH entails worse consequences for the hepatocytes than systemic hemorrhage. Higher needs for resuscitation fluids, decreased proliferation, and augmented inflammatory response when HH takes place are findings with possible clinical importance in liver surgery and trauma.
Subject(s)
Hepatectomy/adverse effects , Postoperative Complications/etiology , Postoperative Complications/metabolism , Shock, Hemorrhagic/etiology , Shock, Hemorrhagic/metabolism , Animals , Blood Loss, Surgical , Disease Models, Animal , Hemodynamics , Liver/metabolism , Liver/pathology , Male , Postoperative Complications/pathology , Postoperative Complications/therapy , Random Allocation , Resuscitation , Shock, Hemorrhagic/pathology , Shock, Hemorrhagic/therapy , SwineABSTRACT
The activity of 1-alkyl-sn-glycero-3-phosphate:Acetyl-CoA acetyltransferase, which catalyses the first step of the de novo biosynthesis of PAF, was determined and characterised in cortical and medullary human renal tissues. A novel thin-layer chromatographic system as well as a trichloroacetic acid precipitation method, were utilised in order to determine the enzyme's activity. The acetyltransferase activity was associated with the membranous fractions of the renal tissue, it showed an optimum pH of 8.4 and it had a bell-shaped dependence on BSA concentration. One or more disulphide bonds were necessary for the action of acetyltransferase while the enzyme seemed to be independent from divalent cations. Two assay products were extracted from the incubation mixture namely alkylacetylphosphatidic acid, produced by the acetylating action of the acetyltransferase on alkyllyso-phosphatidic acid and alkylacetyl-glycerol, which is produced by the action of a phosphohydrolase on alkylacetylphosphatidic acid. The presence of NaF in the assay mixture resulted to a decreased degradation of alkylacetylphosphatidic acid, as well as to an increased overall product formation. Cortical and medullary acetyltransferases share similar biochemical properties and there is no statistical difference between the two activities.
Subject(s)
Acyltransferases/chemistry , Cell Membrane/chemistry , Chromatography, Thin Layer/methods , Kidney Cortex/chemistry , Kidney Medulla/chemistry , Trichloroacetic Acid/chemistry , Acyltransferases/analysis , Animals , Cattle , Cell Membrane/enzymology , Enzyme Activation/drug effects , Glyceryl Ethers/chemistry , Humans , Hydrogen-Ion Concentration , Kidney Cortex/enzymology , Kidney Medulla/enzymology , Phosphatidic Acids/chemistry , Platelet Activating Factor/biosynthesis , Serum Albumin, Bovine/chemistry , Sodium Fluoride/pharmacologyABSTRACT
Platelet-activating factor (PAF) is one of the most potent inflammatory mediators. It is biosynthesized by either the de novo biosynthesis of glyceryl ether lipids or by remodeling of membrane phospholipids. PAF is synthesized and catabolized by various renal cells and tissues and exerts a wide range of biological activities on renal tissue suggesting a potential role during renal injury. The aim of this study was to identify whether cortex and medulla of human kidney contain the acetyl-CoA:1-O-alkyl-sn-glycero-3-phosphocholine acetyltransferase (lyso-PAF AT) activity which catalyses the last step of the remodeling biosynthetic route of PAF and is activated in inflammatory conditions. Cortex and medulla were obtained from nephrectomized patients with adenocarcinoma and the enzymatic activity was determined by a trichloroacetic acid precipitation method. Lyso-PAF AT activity was detected in both cortex and medulla and distributed among the membrane subcellular fractions. No statistical differences between the specific activity of cortical and medullary lyso-PAF AT was found. Both cortical and medullary microsomal lyso-PAF ATs share similar biochemical properties indicating common cellular sources.
