Liver lipid composition and intravenous, intraperitoneal, and enteral administration of intralipid.

We studied the variations arising in plasma and liver lipids after intravenous (i.v.), intraperitoneal (IP), and intragastric (IG) administration of a fat overdose on the order of 4 g.kg-1 body wt.day-1 in the form of Intralipid (ITL) 20% to 33 New Zealand rabbits for 15 days. The control group was submitted for surgery but did not receive an ITL supplement. The results show weight gain in all animals and normal liver enzyme values. There was an increase in plasma lipids in groups supplemented by the parenteral route (i.v. and IP), and fatty acids showed a similar distribution, in terms of percentages, to that for ITL. In liver tissue, there was an increase in the fractions related to ethanolamine and a decrease in phospholipids of choline and serine. In the i.v. group, neutral lipids predominated compared with other groups. The livers of all supplemented animals (i.v., IP, and IG) showed a higher content of stearic and linoleic acid and a reduction in oleic acid. Study with optical microscopy showed a microvacuolization affecting the three areas of the hepatic acini in the i.v. group, seen with electron microscopy as vacuoles lacking membranes and surrounded by mitochondria. In conclusion, there is an increase in hepatic steatosis in parenteral groups and a greater deposit of neutral lipids in the i.v. group, related to the administration route, without biochemical signs of liver dysfunction.

[Interferences between nutrients in their absorption from the peritoneal cavity in rats]. / Interferencias entre nutrientes en su absorción desde la cavidad peritoneal de ratas.

With the aim of detecting possible interferences in the absorption of glucose, amino acids and fats we infused several combination of them into the peritoneal cavity of the Wistar rats. After intraperitoneal infusion of 2 mu Ci-L-glucose-C14 with 5 ml of D-glucose 5 per 100 and L-glucose-C14 with 5 ml of "16N" 3.5 per 100 in different groups of animals, we detected slight differences in plasma radioactivity one hour after infusion. We also found moderated differences in plasma radioactivity among the groups of animals infused with 1 mu Ci of fat radioactive amino acids plus 5 ml of D-glucose 5 per 100 and in the group infused with 1 mu Ci of 5-L-amino acid-C14 plus 5 ml of "16N" 3.5 per 100, after four hours of the infusion. We found no differences among those groups of animals infused with fat plus glucose and with fat plus amino acid with respect to those infused with fat alone. In summary, as glucose and amino acid absorption pathway are the same (capillary flow) seem reasonable that they interfere with each other when they are infused intraperitoneally. Fat infusion that not seem to interfere with other substrates possible due to the different absorption pathway (lymphatic channels) but further studies are needed to determine this.

[Nutrient absorption rate from the peritoneal cavity in rats]. / Velocidad de absorción de nutrientes desde la cavidad peritoneal de ratas.

A study has been done of the absorption/elimination kinetics of nutritive substances such as glucose, amino acids and fats from the peritoneal cavity. For this purpose, 48 male Wistar rats were administered an intravenous or intraperitoneal "bolus" of 2 microCi of L-glucose-C14/250 g of body weight, 3 microCi of D-alanine-L-C14/250 g and 0.4 g of Intralipid/250 g body weight. A two-compartment pharmacokinetic model was applied to determine the absorption, elimination and distribution constants among the different body compartments of each of these substrates, as well as the absorption and elimination halflife. When the areas under the curves were compared following intravenous and intraperitoneal infusion, the total physiological availability or fraction of dose absorbed over a given period of time were calculated. A higher absorption and elimination constant for glucose and amino acids as compared to fats was found. Higher than 90% absorption for all substrates was found, but since in the case of fats the elimination constant is lower and longer the elimination halflife, we must be cautious regarding its infusion rate.

[Intrahepatic cholestasis associated with parenteral nutrition: an experimental study in rats]. / Colestasis intrahepática asociada a nutrición parenteral: estudio experimental en ratas.

Intrahepatic cholestasis is a condition often observed in patients receiving parenteral nutrition, especially in new born babies who are underweight (< 1,000 g.) Some authors find an alteration in the amino acids transulphuration passage, which gives rise to a deficit of taurina. This makes it impossible to achieve a correct conjugation of toxic biliary acids. The access of nutrients to the liver may have an effect on this. An experimental study on rats was performed, administering an oral diet at the expense of lipids (20% Intralipid, 60% of caloric needs) and glucose (40% of caloric needs) in one group, another group received amino acid supplements to this diet (16N) at a proteic rate of 2 gr/kg of weight and day orally, with an identical diet to the above, except that the proteic intake was intraperitoneal. Two control groups were established. We found a microvacuolization in hepatic fat with the help of an electronic microscope in the groups lacking proteins and those with oral or intraperitoneal supplements of amino acids, as well as an increase in plasmatic AST.