Effects of Hypoxia on Choline Exchange Among Organs

Cerebral blood flow (CBF) and the arteriovenous (A-V) difference for choline (Ch) across brain, lung, splanchnic territory, liver, kidney, and lower limb were studied in anesthetized, mechanically ventilated rats subjected to 10-20-min periods of hypoxia induced by lowering the inspired O2 concentration to 13%. A large, time-dependent increase in arterial blood Ch concentration occurred during hypoxia. This phenomenon coincided with a net rate of uptake of Ch by the brain during hypoxia (0.81 +/- 0.24 nmol/min, n = 10; p less than 0.05), which contrasted with a net rate of loss of Ch by this organ during the control period that preceded hypoxia (-0.20 +/- 0.08 nmol/min, n = 10; p less than 0.05). During hypoxia, lungs and splanchnic territory showed negative A-V differences for Ch levels (net Ch loss), whereas brain, liver, kidney, and lower limb showed positive A-V differences for Ch levels (net Ch uptake). Ch output from lungs was already detected at 5 min within the period of hypoxia and reversed rapidly after restoration of normal oxygenation. On the other hand, Ch output from the splanchnic territory became evident only 10 min after commencement of hypoxia and outlasted this experimental condition. It is concluded that extracerebral production of Ch during hypocapnic hypoxia raises the arterial concentration of this molecule and, by reversing the gradient across cerebral capillaries, prevents the cerebral loss of Ch in this condition.     

Lipid peroxidation in plasma of rats treated with ferric-nitrilotriacetate, in relation to kidney and liver modifications

Intraperitoneal injection of the iron chelate ferric-nitrilotriacetate (Fe-NTA) induces in rodents renal and hepatic suffering, associated with oxidative damage. We investigated the oxidation pattern in plasma of treated rats in relation to liver and kidney, monitoring the variation of the lipid components more susceptible to oxidation, unsaturated fatty acids (UFA) and alpha-tocopherol, as biomarkers of the oxidative damage. A sublethal dose of Fe-NTA induced a strong and extremely significant decrease of UFA levels at 1 h after injection in the plasma compartment and at 3 h in the kidney, with reductions up to 40-50% of the control values, together with an increase of conjugated dienes fatty acids hydroperoxides and a consumption of alpha-tocopherol. The same modifications were observed in the liver, but to a lesser extent. Histological observation proved that biochemical changes in the lipid fraction were a direct consequence of an ongoing membrane lipid peroxidation process. Our data show that oxidative damage to the lipid fraction is initially evident in the plasma compartment, where Fe-NTA toxicity is assumed to be caused by the elevation of serum free iron concentration, and proceeds with different speed and severity in the kidney and liver.     

Lipoprotein lipase activity determined in vivo is lower in carriers of apolipoprotein A-V gene variants 19W and -1131C

The apolipoprotein A-V (apo A-V) plays an important role in regulation of triglyceride (TG) concentration in serum. To better understand how apo A-V affects triglyceridemia and glucoregulation, the lipoprotein lipase (LPL) activity was determined using intravenous fat tolerance test (IVFTT) and oral glucose tolerance test (oGTT) was performed in carriers of apolipoprotein A-V gene (APOAV) variants known to be associated with increased triglyceridemia. Twelve carriers of 19W variant, 16 carriers of -1131C variant, 1 combined heterozygote and 16 control subjects homozygous for wild type variants (19S/-1131T) were selected from a population sample and matched with respect to body mass index and age. The APOAV variants carriers had increased TG, very low density lipoprotein-TG, and apo B concentrations (p < 0.05). The LPL activity evaluated as k(2) rate constant for clearance of Intralipid was 14 % lower in APOAV variants carriers. The depression of nonesterified fatty acids (NEFA) concentration after glucose load was delayed in APOAV variants carriers in spite of the same insulinemia and glycemia. Our results suggest that variants of APOAV combined with increased triglyceridemia are associated with lower LPL activity in vivo and with disturbances of regulation of NEFA concentration after glucose load.     

Temporal changes in plasma and liver lipids and in the hepatic activities of acetyl-coenzyme a carboxylase and fatty acid synthetase after oestrogen treatment of the male chicken (Gallus domesticus)

1. Male chickens (Gallus domesticus) were treated with a single intramuscular injection of oestradiol-17 beta, then changes in the liver and plasma levels of triacylglycerol, phospholipid, nonesterified fatty acids and in the hepatic activities of acetyl-CoA carboxylase and fatty acid synthetase were measured at various times after injection. 2. The results suggest that the initial phase (less than 20 hr) of oestrogen-induced hyperlipidaemia occurs in the absence of changes in the hepatic activities of the major enzymes of fatty acid biosynthesis, but a subsequent increase in these enzyme activities may contribute to the later phase (greater than 20 hr) of oestrogen-induced lipogenesis in avian liver.     

Metabolism of doubly-labeled chylomicron cholesteryl esters in the rat

Chylomicrons labeled in vitro with doubly-labeled cholesteryl esters were injected intravenously into fasted rats, and the tissue distribution and chemical form of each isotope were observed for 24 hr. The use of doubly-labeled cholesteryl esters provided information about the metabolism of both the sterol and the fatty acid moieties. Similar results were obtained with doubly-labeled cholesteryl palmitate, oleate, and linoleate. In each instance, most (80-90%) of the chylomicron cholesteryl ester was removed from the plasma by the liver; small amounts were also taken up by all other tissues examined. There was no hydrolysis during uptake. In the liver the newly absorbed cholesteryl esters underwent slow hydrolysis (60% after 1 hr and 85-90% after 3.5 hr); the rate of reesterification of the liberated cholesterol was still slower. After 24 hr only 20-28% of the labeled cholesterol present in the animal was found in the liver. Labeled fatty acid disappeared from the liver, and was redistributed among other tissues, much more rapidly than the labeled cholesterol. Most of the labeled fatty acid apparently underwent oxidation, since only 15-20% of the injected labeled fatty acid was present in the animal after 24 hr. At this time the three fatty acids were differently distributed between and within the tissues. These differences reflected some known differences of fatty acid concentration and lipid composition in the various tissues.     

Effects of Desacetyl-alpha-MSH on Lipid Mobilization in the Rainbow Trout, Oncorhynchus mykiss

Effects of melanocyte-stimulating hormone (MSH) and beta-endorphin on lipid mobilization were examined in the rainbow trout (Oncorhynchus mykiss). Plasma levels of fatty acid (FA) were measured after intra-arterial administration of alpha-MSH, desacetyl-alpha-MSH, beta-MSH, or beta-endorphin through a cannula in the dorsal aorta. Desacetyl-alpha-MSH at 1 ng/g body weight resulted in an increase in plasma FA levels 1-3 hr after the injection, whereas the other three peptides showed no significant effect at the same dose. There was no significant change in plasma levels of cortisol after administration of any of the peptides. Lipolytic enzyme activity in the liver was significantly increased in a dose-related manner 1 hr after single intra-peritoneal injection of desacetyl-alpha-MSH. The direct effect of desacetyl-alpha-MSH on lipolysis was examined in liver slices incubated in vitro. Lipase activity in the liver slice was stimulated in the medium containing desacetyl-alpha-MSH in a dose-related manner. The results indicate that desacetyl-alpha-MSH is a potent stimulator of lipid mobilization in the rainbow trout.     

Avian apolipoprotein A-V binds to LDL receptor gene family members

Apolipoprotein A-V (apoA-V) affects plasma triglyceride (TG) levels; however, the properties of apoA-V that mediate its action(s) are still incompletely understood. It is unclear how apoA-V, whose plasma concentration is extremely low, can affect the pronounced TG differences observed in individuals with various apoA-V dysfunctions. To gain novel insights into apoA-V biology, we expanded our previous studies in the chicken to this apolipoprotein. First, we characterized the first avian apoA-V, revealing its expression not only in liver and small intestine but also in brain, kidney, and ovarian follicles and showing its presence in the circulation. Second, we demonstrate directly that galline apoA-V binds to the major LDL receptor family member (LR) of the laying hen and that this interaction does not depend on the association of the apolipoprotein with lipid or lipoproteins. We propose that a direct interaction with LRs may represent a novel, additional mechanism for the modulation of TG levels by apoA-V.     

Rapid activation and inactivation of fatty acid synthesis from glucose in vivo

The flux of glucose carbon to total body fatty acids was measured in unanesthetized mice either after fasting or 50-80 min after they nibbled a small test meal containing 120 mg of glucose (fasted-refed). Flux was calculated from plasma [(14)C]glucose specific activity curves and from total body (14)C-labeled fatty acid 30 min after intravenous injection of tracer [(14)C]glucose. Mobilization of liver glycogen, changes in the body glucose pool size, and total flux of carbon through the glucose pool during periods of fasting and refeeding were defined. Liver glycogen was almost completely depleted 8 hr after food removal. Body glucose pool size fell during fasting and increased after refeeding the test meal. Irreversible disposal rate of glucose C varied directly with body glucose pool size; but flux of glucose C into fatty acids increased exponentially as body glucose concentration increased. Within an hour after nibbling a small test meal, the flux of glucose C into total body fatty acids increased 700% in mice previously starved for 24 hr. However, flux of glucose C into fatty acids in postabsorptive mice (food removed for 2 hr; livers rich in glycogen) was only about 2% of the value calculated from published studies in which the incorporation of an intubated [(14)C]glucose load into total body fatty acid was measured in mice. A possible explanation for this phenomenon is presented.     

Effect of glucamylase on tissue glycogen and tissue glucamylase in the rat

1. A fungal glucamylase (alpha-1,4-glucan glucohydrolase, EC 3.2.1.3) from Aspergillus niger depresses liver glycogen stores after intraperitoneal injection into the rat. The injected enzyme rapidly disappears (within about 8hr.) from the serum; less than 1% is excreted in the urine, but it is rapidly taken up in the liver, spleen, kidney, cardiac and skeletal muscle. Elevated glucamylase concentrations could be demonstrated in liver and spleen tissues for 1-4 days after injection, but in kidney, cardiac and skeletal muscle elevated glucamylase concentrations could be shown only for periods of less than 24hr. after injection of the enzyme.     

Time course of distribution to tissues of 125I-somatomedin A injected into the rat

125I-somatomedin A (SMA) was injected iv into rats. Distribution studies in rats showed concentrations of radioactivity to be high in kidney and plasma, low in brain, and intermediate in other tissues. The concentration of total and trichloracetic acid (TCA) precipitable radioactivity in rat blood and tissues fell at rapid rate. Ninety per cent of the radioactivity was in the urine in 24 hr, and only 15% of urine radioactivity was TCA precipitable. The half-life of the radioactivity in TCA-precipitable fraction from blood and that from tissues were nearly identical (about 6 hr). In both liver and kidney, TCA-precipitable radioactivity was detected in membrane and/or organellar fraction and cytosol fraction. Sephadex G-200 chromatography at neutral PHY AT NEUTRAL PH of plasma after injection of 125I-SMA revealed 3 peaks of radioactivity in higher molecular weight region than purified SMA.     

Effect of cold exposure on the concentration of triglyceride in the liver of the rat

The aim of the present study was to examine an effect of cold exposure on the concentration of triglycerides (TG) in the rat's liver. The rats were divided into the following groups: control, fed with oil, treated with hydrocortisone, fed with oil and treated with hydrocortisone, treated with noradrenaline. The rats exposed to cold were kept in wire cages (one rat in one cage) in the cold room at temperature +2 degrees C. They had free access to food (pellet diet for rodents) and water. In the control group the exposure to cold increased mildly (though significantly) the TG concentration after 1 and 3 h and had no effect after 2 and 24 h. It did not affect the concentration of plasma free fatty acids (FFA). At room temperature feeding with oil (2 ml/100 g of body weight) alone, and combined with hydrocortisone treatment (5 mg/100 g of body weight) as well as treatment with noradrenaline (0.1 mg/100 g of body weight) had no effect on the liver TG concentration, although the concentration of plasma FFA was increased. Exposure to cold for 3 h increased markedly the liver TG concentration in each of those groups. It is concluded that exposure to cold elicits a mechanism, which in the presence of elevated plasma FFA concentration induces accumulation of TG in the liver.     

富含不饱和脂肪酸饲料对大鼠血液学指标及主要脏器的影响

目的探讨富含不饱和脂肪酸饲料对SD大鼠血液学指标及主要脏器的影响。方法以富含不饱和脂肪酸的青花椒籽油饲料饲喂断乳SD大鼠60d,试验结束时测定部分血清学和血液细胞学指标及脑、心脏、肝脏、肾脏、脾脏系数,并对心脏、肝脏、肾脏进行病理学观察。结果实验组雄性大鼠与正常对照组同性别大鼠相比,甘油三脂和低密度脂蛋白显著降低（P〈0．05）,实验组饲料极显著提高雄性大鼠大脑系数,极显著提高雄性和雌性大鼠肝脏和肾脏系数（P〈0．01）;心脏、肝脏、肾脏病理学观察结果为阴性。结论富含不饱和脂肪酸饲料对大鼠血清学指标有一定影响,对大鼠心、肝、。肾组织无明显影响。     

Analysis and quantitation of free ceramide containing nonhydroxy and 2-hydroxy fatty acids, and phytosphingosine by high-performance liquid chromatography.

Reaction of ceramides containing nonhydroxy fatty acids with benzoyl chloride in pyridine at 70 degrees C for 1 hr resulted in N-benzoylation to form N,N-acyl,benzoyl derivatives; O-benzoylation also occurred. However with ceramides containing 2-hydroxy fatty acids and phytosphingosine only O-benzoylation occurred even on prolonged treatment. Only O-benzoylation occurred on reaction with benzoic an hydride. However, the benzoylation of ceramides with phytosphingosine could not be achieved with benzoic anhydride and this benzoylation was performed by reaction with benzoyl chloride at 70 degrees C for 4 hr. Because N,N-acyl,benzoyl derivatives of ceramides containing nonhydroxy fatty acids produced by treatment with benzoyl chloride overlap methyl benzoate on high-performance liquid chromatography, benzoic anhydride was preferable for benzoylation of ceramides with nonhydroxy and 2-hydroxy fatty acids. On the other hand, the reaction with benzoyl chloride at 70 degrees C for 4 hr was used for quantitation of benzoylated ceramides containing 2-hydroxy fatty acids and phytosphingosine. 3-(p-Phenylbenzoyl)estrone was used as an internal standard for both reactions and values for ceramides containing 2-hydroxy fatty acids obtained by the two reactions were in good agreement. This procedure was applied to measurement of the ceramide levels in the brain, liver, and kidney of rats during development. The levels of ceramides containing nonhydroxy and 2-hydroxy fatty acids in the brain, liver, and kidney increased to the adult levels and then remained unchanged. Ceramide with phytosphingosine was detected in the liver and kidney, where its concentration gradually increased with age, but it was not found in the brain. The composition of nonhydroxy fatty acids were also analyzed.     

Interactions of selenium and cadmium with metallothionein-like and other cytosolic proteins of rat kidney and liver

Following injection of rats with CdCl2 and [75Se]selenite using five different protocols, the metallothionein-like proteins (MTLPs) of kidney and liver cytosols were fractionated by Sephadex G-75 gel filtration and DEAE Sephacel ion-exchange chromatography. Cd and 75Se distribution in gel-filtration elution profiles was influenced mainly by the time that elapsed between administration of these elements and by the sequence of their administration. There was no Cd redistribution to high molecular weight proteins after long-term Cd injection when rats were killed 48 hr after 75Se injection. Cd was redistributed from MTLP to high molecular-weight proteins in the liver when Cd and 75Se were injected within 1-3 hr of each other. Incorporation of 75Se into MTLP of kidney and liver was independent of Cd injection. The strength of 75Se binding of MTLP was comparable to the covalent binding of 75Se to glutathione peroxidase. Cd and 75Se did not share binding sites on MTLP. In ligand-exchange studies, 1000 ppm Cd did not displace 75Se from MTLP, but 2% 2-mercaptoethanol displaced 10% of the presumably nonspecifically bound 75Se from kidney and liver MTLP. This study provides new information regarding the apparent covalent binding of Se to low molecular-weight, Cd-containing proteins in kidney and liver.     

The Hyplip2 locus causes hypertriglyceridemia by decreased clearance of triglycerides

The Hyplip2 congenic mouse strain contains part of chromosome 15 from MRL/MpJ on the BALB/cJ background. Hyplip2 mice show increased plasma levels of cholesterol and predominantly triglycerides (TGs) and are susceptible to diet-induced atherosclerosis. This study aimed at elucidation of the mechanism(s) explaining the hypertriglyceridemia. Hypertriglyceridemia can result from increased intestinal or hepatic TG production and/or by decreased LPL-mediated TG clearance. The intestinal TG absorption and chylomicron formation were studied after intravenous injection of Triton WR1339 and an intragastric load of olive oil containing glycerol tri[(3)H]oleate. No difference was found in intestinal TG absorption. Moreover, the hepatic VLDL-TG production rate and VLDL particle production, after injection of Triton WR1339, were also not affected. To investigate the LPL-mediated TG clearance, mice were injected intravenously with glycerol tri[(3)H]oleate-labeled VLDL-like emulsion particles. In Hyplip2 mice, the particles were cleared at a decreased rate (half-life of 25 +/- 6 vs. 11 +/- 2 min; P < 0.05) concomitant with a decreased uptake of emulsion TG-derived (3)H-labeled fatty acids by the liver and white adipose tissue. The increased plasma TG levels in Hyplip2 mice do not result from an enhanced intestinal absorption or increased hepatic VLDL production but are caused by decreased LPL-mediated TG clearance.     

Lipid metabolism response to a single, prolonged bout of endurance exercise in healthy young men

To discover the alterations in lipid metabolism linked to postexercise hypotriglyceridemia, we measured lipid kinetics, lipoprotein subclass distribution and lipid transfer enzymes in seven healthy, lean, young men the day after 2 h of cycling and rest. Compared with rest, exercise increased fatty acid rate of appearance and whole body fatty acid oxidation by approximately 65 and 40%, respectively (P < 0.05); exercise had no effect on VLDL-triglyceride (TG) secretion rate, increased VLDL-TG plasma clearance rate by 40 +/- 8%, and reduced VLDL-TG mean residence time by approximately 40 min and VLDL-apolipoprotein B-100 (apoB-100) secretion rate by 24 +/- 8% (all P < 0.05). Exercise also reduced the number of VLDL but almost doubled the number of IDL particles in plasma (P < 0.05). Muscle lipoprotein lipase content was not different after exercise and rest, but plasma lipoprotein lipase concentration increased by approximately 20% after exercise (P < 0.05). Plasma hepatic lipase and lecithin:cholesterol acyltransferase concentrations were not affected by exercise, whereas cholesterol ester transfer protein concentration was approximately 10% lower after exercise than after rest (P = 0.052). We conclude that 1) greater fatty acid availability after exercise does not stimulate VLDL-TG secretion, probably because of the increase in fatty acid oxidation and possibly also fatty acid use for restoration of tissue TG stores; 2) reduced secretion of VLDL-apoB-100 lowers plasma VLDL particle concentration; and 3) increased VLDL-TG plasma clearance maintains low plasma TG concentration but is not accompanied by similar increases in subsequent steps of the delipidation cascade. Acutely, therefore, the cardioprotective lowering of plasma TG and VLDL concentrations by exercise is counteracted by a proatherogenic increase in IDL concentration.     

Fatty liver and hyperlipidemia in IDDM (insulin-dependent diabetes mellitus) of streptozotocin-treated shrews

Severe IDDM (insulin-dependent diabetes mellitus) was produced in the musk shrew (Suncus murimus, Insectivora) by a high dose (a single intraperitoneal injection of 100 mg/kg Body Weight) of streptozotocin (STZ) injection. All shrews that were administered a high dose of STZ exhibited hyperglycemia (449 +/- 16 mg/dl vs 73 +/- 4 mg/dl in controls) and hypoinsulinemia(0.25 +/- 0.07 ng/ml vs 10.96 +/- 1.97 ng/ml in controls) with ketosuria 10 days after injection. Their livers were enlarged and exhibited ayellowish-brown color with marked triglyceride (TG) accumulation (63.25 +/- 7.10 mg/g Liver vs 2.11 +/- 0.19 mg/g Liver in controls). It is probable that the increased influx of fatty acids into the liver induced by hypoinsulinemia and the low capacity of excretion of lipoprotein secretion from liver in the musk shrew resulting from a deficiency of apolipoprotein B synthesis play important roles in fatty liver formation. Hyperlipidemia was another feature in shrews with severe IDDM. The blood TG level was especially high in these shrews (899 +/- 178 mg/dl vs 23 +/- 5 mg/dl in controls). These results indicate that the IDDM shrew, induced by high doses of STZ, is a unique model characterized by fatty liver and hyperlipidemia and may be useful for studying lipid metabolism of IDDM.     

Fatty acid changes in liver and plasma lipid fractions after safflower oil was fed to rats deficient in essential fatty acids

1. Fatty acid patterns of liver and plasma triglycerides, phospholipids and cholesteryl esters were determined at intervals during 24hr. after essential fatty acid-deficient rats were given one feeding of linoleate (as safflower oil). 2. Liver triglyceride, phospholipid and cholesteryl ester fatty acid compositions did not change up to 7hr. after feeding. Between 7 and 10hr., linoleic acid began to increase in all fractions, but arachidonic acid did not begin to rise in the phospholipid until 14-19hr. after feeding. 3. Oleic acid and eicosatrienoic acid in liver phospholipid began to decline at about the time that linoleic acid increased, i.e. about 9hr. before arachidonic acid began to increase. 4. Changes in linoleic acid, arachidonic acid and eicosatrienoic acid in phosphatidylcholine resembled those of the total phospholipid. Phosphatidylethanolamine had a higher percentage content of arachidonic acid before the linoleate was given than did phosphatidylcholine, and after the linoleate was given the fatty acid composition of this fraction was little changed. 5. The behaviour of the plasma lipid fatty acids was similar to that of the liver lipids, with changes in linoleic acid, eicosatrienoic acid and arachidonic acid appearing at the same times as they occurred in the liver. 6. The results indicated that linoleic acid was preferentially incorporated into the liver phospholipid at the expense of eicosatrienoic acid and oleic acid. The decline in these fatty acids apparently resulted from their competition with linoleic acid for available sites in the phospholipids rather than from any direct replacement by arachidonic acid.     

Distribution of amiodarone and its metabolite, desethylamiodarone, in human tissues

The distribution of the antiarrhythmic drug amiodarone and its principal lipophilic metabolite, desethylamiodarone, was determined in postmortem tissues of six patients who received amiodarone therapy (treatment period, 6-189 days; total dose, 4.8-127.0 g). Amiodarone concentration was highest in liver, lung, adipose tissue, and pancreas, followed by kidney, heart (left ventricle), and thyroid gland, and lowest in antemortem plasma. There was no measurable amiodarone in brain (less than 1.0 microgram/g). Desethylamiodarone concentration was highest in liver and lung, followed by pancreas, adipose tissue, kidney, heart, thyroid gland, and brain, and lowest in plasma. For most patients, the desethylamiodarone concentration was higher than the amiodarone concentration in liver, lung, kidney, heart, thyroid gland, and brain, whereas the parent drug concentration was higher than the metabolite concentration in adipose tissue, pancreas, and plasma. Tissue amiodarone and desethylamiodarone concentrations appeared to be related more closely to the total dose of amiodarone than to their respective plasma concentrations. One patient died of apparent amiodarone-induced pulmonary toxicity after an 18-day period of pharmacotherapy. Clinical evidence of pulmonary dysfunction appeared at 15 days after the initiation of amiodarone therapy, and the patient died at 23 days. Histologic assessment of a lung necropsy specimen revealed acute alveolar interstitial damage. This case represents the earliest reported incident of amiodarone-induced pulmonary toxicity.     

Iron mobilization in estrogenized male quail

A single diethylstilbestrol (DES) injection (5 mg DES/100 g body wt) was administrated to several lots (three specimens each) of adult male quail (Coturnix coturnix japonica). The birds were sacrificed 24, 48, 72 and 96 hr after the DES injection. A significant increase in liver weight and a clear drop in the hemoglobin concentration were observed after 24 hr. Later, a progressive rise was observed in plasma iron, total iron binding capacity, plasma copper and the phosphoprotein (vitellogenin), which reached highest values after 96 hr. In the liver, the iron showed an initial increase (24 hr), due to a rise in non-ferritin iron followed by a progressive decrease. Ferritin iron increased slowly but was significantly higher after 96 hr. This experimental model on male quail suggests an estrogen response in birds that could be more general and uniform than in mammals.