Effects of progesterone metabolites on fatty acids of the hepatic endoplasmic reticulum membranes

The effect of 2 selected progesterone metabolites on the phospholipid fatty acid composition of the liver and microsomal function was studied in the female rat. 16α-Hydroxyprogesterone significantly increased microsomal phospholipid content and the total amount of fatty acids esterified to phospholipids parallel with aminopyrine N-demethylase activity. Phospholipid changes were attributable to phosphatidylcholine and phosphatidylethanolamine. Both saturated and unsaturated fatty acids were enhanced. In contrast, 5β-pregnane-3α-ol-20-one caused a reduction of microsomal phospholipids, phosphatidycholine, together with decreased aminopyrine N-demethylase activity and total microsomal fatty acid content. Pregnanolone decreased both saturated and unsaturated fatty acids and its action on unsaturated acyl components was greater than on the saturated ones. Changes in fatty acids were manifested in palmitic, stearic and lignoceric acids among saturated fatty acids and in palmitoleic, oleic, linoleic, eicosaenoic, eicosadienoic, eicosatrienoic, arachidonic, eicosapentenoic, docosatrienoic, docosapentenoic and docosahexenoic acids among unsaturated ones. Total liver phospholipids were unaltered by either 16α-hydroxyprogesterone or 5β-pregnane-3α-ol-20-one. These test compounds, however, modified total hepatic fatty acid content. 16α-Hydroxyprogesterone increased total fatty acids and both saturated and unsaturated acyl components, whereas 5β-pregnane-3α-ol-20-one decreased these parameters. Major changes were manifested in saturated fatty acids such as stearic, arachidic and lignoceric acids, and in unsaturated ones such as palmitoleic, linoleic, eicosatrienoic and docosapentenoic acids. The action of these compounds on phospholipid fatty acids of hepatic microsomes may be causally related to their effect on drug-metabolizing activity of the endoplasmic reticulum.     

The effects of intermittent nitrogen dioxide exposure on vitamin E-deficient and -sufficient rats

In two separate experiments rats fed vitamin E-deficient, normal or high vitamin E-supplemented diets were intermittently exposed to 15 ppm ± 1.0 ppm nitrogen dioxide (NO₂) over a 5-week (4 days/week, total of 31.5 h exposure) or an 18-week (5 days/week, total of 93.5 h exposure) period. In the 5-week, NO₂-exposed rats, the blood methemoglobin levels were not influenced by NO₂ exposure or the level of vitamin E in the diet. Tissues of the rats exposed to NO₂ for 18 weeks showed some histological changes; in the lung, increased atelectasis and alveolar thickening and in the liver, increased granular changes, karyolysis and karyorhexis. These differences were suppressed by increasing levels of dietary vitamin E. Tissue lipofuscin pigment (LFP) concentrations were not affected by NO₂ exposure or dietary vitamin E. Fatty acid distribution of lung lipid extracts showed no changes due to NO₂ exposure; however, some effects of dietary vitamin E could be seen. The results suggest that intermittent NO₂ exposure, under the described conditions, did not cause ultimate changes of the biochemical parameters measured.     

Effect of acute nitrogen dioxide exposure on the prostacyclin synthesis in lung

The effect of acute nitrogen dioxide (NO₂) exposure on prostacyclin synthesis in the rat lung was studied. Male Wistar rats were exposed to 5, 10, 15, 20 and 25 ppm NO₂ for 24 h. Dose-dependent decrease in prostacyclin-synthesizing activities of both homogenized and intact lung was observed. This decrease in prostacyclin synthesis following NO₂ exposure may be related to formation of lipid peroxides due to NO₂ exposure and to damage of pulmonary epithelial cells and endothelial cells by NO₂ exposure.     

Effects of dehydroepiandrosterone on oleic acid accumulation in rat liver

The purpose of the present study was to determine whether dehydroepiandrosterone (DHEA) affects de novo fatty acid synthesis, oleic acid formation, fatty acid oxidation, and very low density lipoprotein (VLDL) secretion, in relation to the accumulation of lipid containing oleic acid, in rat liver. The rates of hepatic de novo synthesis of both fatty acid and monounsaturated fatty acid, determined by incorporation of 3H from 3H(2)O into fatty acid, were increased markedly when rats were fed a diet containing 0.5% (w/w) DHEA for 14 days. The treatment of rats with DHEA also enhanced the conversion of [14C]stearic acid into oleic acid in the liver in vivo. DHEA did not suppress fatty acid degradation in the liver. Namely, mitochondrial palmitic acid oxidation in liver homogenates and isolated hepatocytes was increased approximately 1.9- and 5-fold, respectively, in DHEA-treated rats. Peroxisomal palmitic acid oxidation in isolated hepatocytes from rats treated with DHEA, however, was not significantly different from that of the control, despite the fact that peroxisomal degradation of palmitic acid in the liver homogenates was increased markedly. The rate of hepatic VLDL secretion in DHEA-treated rats was decreased markedly. These results indicate that the elevation of the hepatic fatty acid content, especially oleic acid, by DHEA feeding is due to an increase in both de novo fatty acid synthesis and the formation of oleic acid and to a decrease in the rate of hepatic VLDL secretion. Mitochondrial and peroxisomal fatty acid degradation does not appear to play a significant role in the accumulation of hepatic lipids.     

Interspecies variations in fatty acid hydroxylations involving cytochromes P450 2E1 and 4A

The liver microsomal fractions of seven mammalian species including rat, dog, monkey, hamster, mouse, gerbil and humans, catalyzed the hydroxylation of saturated (lauric, myristic and palmitic) and unsaturated (oleic and linoleic) fatty acids to the corresponding omega and (omega-1)-hydroxylated derivatives, while stearic acid was not metabolized. Lauric acid was the most efficiently hydroxylated, and the rank of catalytic activity was lauric > myristic > oleic > palmitic > linoleic. Among the mammalian species studied, mouse and hamster presented the highest level of fatty acid omega and (omega-1)-hydroxylases, while the lowest activity was observed in dog and monkey. In all the animal species, the (omega-1)-hydroxylation of fatty acids correlated significantly with the immunodetectable content of CYP2E1 and the 4-nitrophenol hydroxylation activity, known to be mediated by cytochrome P450 2E1. On the contrary, only the omega-hydroxylation of lauric acid slighly correlated with the level of cytochrome P450 4A, while no significant correlation was found with the omega-hydroxylation of the other fatty acids. Furthermore, chemical and immuno-inhibitions of the hydroxylations of fatty acids led to the conclusion that fatty acid (omega-1)-hydroxylase activity is catalyzed by P450 2E1 in all the mammalian species, while the fatty acid omega-hydroxylase activity may be catalyzed by cytochromes P450 from the 4A family. Therefore, lauric acid (omega-1)-hydroxylation along with 4-nitrophenol hydroxylation can be used as a specific and sensitive method to measure the level of CYP2E1 induction in humans and various animals.     

Are Changes in Breathing Pattern on Exposure to Ozone Related to Changes in Pulmonary Surfactant?

Abstract

Rats respond to the inhalation of ozone with changes in breathing pattern during the exposure and the development of a pulmonary inflammatory response 24–48 h postexposure. We report experiments designed to investigate the relationships between changes in breathing pattern and the composition and surface tension-reducing properties of pulmonary surfactant immediately after the exposure. A total of 64 male Fischer 344 rats were exposed to 0.8 ppm O₃ for 4 h in 4 replicate exposures with matched purified air control exposures and 8 rats per exposure group. Those exposed to O₃ developed the rapid-shallow breathing pattern characteristic of oxidant pulmonary irritation during exposure. The rats were sacrificed immediately following the exposure, and pulmonary surfactant was isolated from samples of bronchoalveolar lavage fluid pooled from groups of eight rats. After esterification, the fatty acid methyl ester composition was measured using GC-MS. in the ozone-exposed animals, the decreases in unsaturated species (linoleic, oleic, palmitoleic, and an unidentified fatty acid) relative to the major saturated component, palmitic acid, were highly statistically significant, while stearic acid showed no significant change. Total protein in the lavage fluids of the exposed animals was not elevated, indicating that sacrifice and analysis were performed early in the O₃ injury-inflammation response sequence, and suggesting that the fatty acid changes in the pulmonary surfactant may be due in part to a direct reaction with inhaled O₃. The group mean change in breath frequency (as percent of matched purified air control values) was significantly correlated with the percent change in lnoleic acid fraction among replicate exposures, suggestive of a possible relationship between ozone-induced changes in pulmonary surfactant and changes in breathing patterns. There was no significant change in the surface pressure-area isotherms of monolayers of pulmonary surfactant upon ozone exposure. However, comparison to isotherms from an in vitro exposure of a synthetic mixture of saturated and unsaturated phospholipids suggests that changes due to the observed change in the fatty acid composition in the in vivo experiments may be too small to be observed. Furthermore, the pulmonary surfactant isolation procedure was specifically designed to recover the undamaged surfactant and may discriminate against products of reaction with ozone; hence the isotherms may not necessarily reflect the actual changes during the exposure. Further experiments to elucidate the interaction of inhaled O₃ with pulmonary surfactant and its relationship to changes in breathing pattern are discussed.     

Analysis of sterols and fatty acids in natural and cultured Cordyceps by one-step derivatization followed with gas chromatography–mass spectrometry

Ten free fatty acids namely lauric acid, myristic acid, pentadecanoic acid, palmitoleic acid, palmitic acid, linoleic acid, oleic acid, stearic acid, docosanoic acid and lignoceric acid and four free sterols including ergosterol, cholesterol, campesterol and β-sitosterol in natural (wild) Cordyceps sinensis, Cordyceps liangshanensis and Cordyceps gunnii, as well as cultured C. sinensis and Cordyceps militaris were first determined using pressurized liquid extraction (PLE), trimethylsilyl (TMS) derivatization and GC–MS analysis. The conditions such as the amount of reagent, temperature and time for TMS derivatization of analytes were optimized. Under the optimum conditions, all calibration curves showed good linearity within the tested ranges. The intra- and inter-day variations for 14 investigated compounds were less than 3.4% and 5.2%, respectively. The results showed that palmitic acid, linoleic acid, oleic acid, stearic acid and ergosterol are main components in natural and cultured Cordyceps which could be discriminated by hierarchical clustering analysis based on the contents of 14 investigated compounds or the 4 fatty acids, where the contents of palmitic acid and oleic acid in natural Cordyceps are significantly higher than those in the cultured ones.     

Changes in the Response of Lung Mast Cells Isolated from Rats and Guinea Pigs Exposed to Nitrogen Dioxide

Abstract

To clarify the relationship between exposure to nitrogen dioxide (NO₂) and mast-cell responses, rats and guinea pigs were exposed to 0, 1.0, 2.0, and 4.0 ppm NO₂ for 12 wk. Although lung wet weights were not changed in both rats and guinea pigs, the number of lung cells from 2.0 and 4.0 ppm NO₂-exposed rats were significantly decreased compared to that of control. No difference was observed in the number of lung mast cells from rats and guinea pigs exposed to NO₂. in lung mast cells from rats, immunoglobulin E (IgE) mediated histamine release was slightly decreased, but A23187-induced histamine release was not changed. On the contrary, in lung mast cells from guinea pigs, IgE-mediated histamine release was increased in a dose-dependent fashion, though no changes in A23187-induced histamine release were observed. These results suggest that different sensitivity for NO₂ exposure exists in lung mast cells from rats and guinea pigs.     

Cholesterol ester hydrolase mediated conjugation of haloethanols with fatty acids

The formation of fatty acid conjugates of haloethanols was studied under in vitro conditions by using purified bovine pancreatic cholesterol ester hydrolase (EC 3.1.1.13). The enzymatic formation of 2-chloroethyl and 2-bromoethyl esters of oleic, linoleic, linolenic, and arachidonic acids was confirmed by proton nuclear magnetic resonance spectroscopy and chemical ionization mass spectrometry. 2-Bromoethanol was a better substrate than 2-chloroethanol for fatty acid esterification using cholesterol ester hydrolase. Among the chloroethanols, 2-chloroethanol was a better substrate than 2,2-dichloroethanol and 2,2,2-trichloroethanol. The saturated fatty acids (palmitic and stearic) showed a small amount of ester formation when cholesterol ester hydrolase was used. The kinetics of haloethanol and oleic acid incorporation into haloethyl oleate catalyzed by cholesterol ester hydrolase were determined. In vitro experiments were also conducted to study the conjugation of haloethanols with fatty acids using rat liver microsomes. The saturated fatty acid (palmitic) was more reactive compared to unsaturated fatty acid (oleic) when haloethanols were used. The results using rat liver microsomes were in contrast to those obtained when cholesterol ester hydrolase was used. The synthesis, purification, and characterization of 2-chloroethyl and 2-bromoethyl esters of oleic, linoleic, linolenic, and arachidonic acids are also described.     

Effect of acute nitrogen dioxide exposure on the free amino acids of rat serum

Female Wistar rats were acutely exposed to 20 ppm nitrogen dioxide (NO₂). After 20 h exposure, the concentrations of valine, leucine, isoleucine and phenylalanine in serum significantly increased. Significant decreases were observed for aspartic acid, threonine, serine, glutamic acid, glycine alanine, cystine, methionine, tyrosine, lysine, arginine and proline. The concentrations of free amino acids of rats exposed to NO₂ for 40 h were close to the values for rats starved for 40 h.     

Plasmalogen chemistry of the calf thymus

A Contribution to the Chemistry of Calf Thymus Plasmalogens The lipid extract of calf thymus contains 6,5 % plasmalogens, of which the ethanolamine plasmalogens constitute 3.07 % and the choline plasmalogens 1.36 %. The plasmalogen aldehydes were determined by gas chromatography of their dimethyl acetal derivatives. The authentic aldehydes were obtained by manganese dioxide oxidation of the respective alcohols. In both the choline and ethanolamine plasmalogen fractions C₁₄, C₁₅, C₁₆, C₁₇, C₁₈, C_18:1, C₂₀, C₂₂ and C₂₄ aldehydes were found. The main components of this mixture are palmitic aldehyde (47.3 - 44.0 %), stearic aldehyde (17.5 - 20.4 %) and oleic aldehyde (14.8 - 21.8 %). C₁₄, C₁₅, C₁₆, C_16:1 C₁₇, C₁₈, C_18:1, C_18:2, C₂₀, C_20:1 C_20:2, C_20:3 and C₂₂ fatty acids could be identified by gas chromatography of the choline and ethanolamine phospholipoids. The esters of oleic and palmitic acids are the most abundant. Linolenic acid is confined to the choline phosphatides, while docosenic acid (C_22:1) is found only in the ethanolamine phosphatides. On the basis of these results the structure of the essential thymus plasmalogens may be elucidated.     

Dietary antioxidants and the biochemical response to oxidant inhalation: I. Influence of dietary vitamin E on the biochemical effects of nitrogen dioxide exposure in rat lung

Sprague-Dawley rats derived from a specific pathogen-free colony were raised from birth on a test diet containing either 0 or 50 IU vitamin E/kg diet for 8 weeks. Rats from each dietary group were exposed to 3 ppm (5640 μg/m³) nitrogen dioxide (NO₂) continuously for 7 days. They were then killed, and the lungs analyzed for changes in weight, DNA and protein contents, tissue oxygen utilization, sulfhydryl metabolism, and the activities of NADP-reducing enzymes. The difference in dietary vitamin E alone did not cause any significant changes in these parameters. However, after NO₂ exposure the changes in these parameters relative to their corresponding unexposed controls were greater for the deficient rats than for the supplemented rats. The biochemical changes observed may be a response of the lung to injury from NO₂ exposure. The larger changes in the lungs of deficient rats may reflect a greater sensitivity of these animals to inhaled NO₂. The vitamin E contents of lung tissue in deficient and supplemented rats reflected the dietary levels. After NO₂ exposure, the vitamin E content in the lung increased significantly in supplemented rats but decreased in the deficient rats relative to their corresponding unexposed controls. The elevation of vitamin E levels in the lungs of supplemented rats with NO₂ exposure suggests its mobilization from other body sites, whereas in deficient rats this process may not have been possible.     

Saturated and monounsaturated fatty acids increase interleukin-10 production in rat hepatocytes.

Interleukin-10 (IL-10) is a potent anti-inflammatory cytokine, but it still remains unknown whether saturated or unsaturated fatty acid affects IL-10 production in hepatocytes that contribute to lipid metabolism. Primary rat hepatocyte cultures were treated with different fatty acids (18:0 stearic acid, 18:1 oleic acid; 18:2 linoleic acid, 18:3 linolenic acid) at 300 microM for 24 hours. The concentrations of IL-2, IL-10, GM-CSF and IFN-gamma in the medium were detected by multiplex cytokine array. IL-10 was significantly increased with treatment of stearic acid and oleic acid. Production of IL-10 by saturated and monounsaturated fatty acids in hepatocytes may be one of the reasons why the lard oil had less inflammation in the hepatic steatosis animal models.     

Combined n-benzoyl-d-phenylalanine and metformin treatment reverses changes in the fatty acid composition of streptozotocin diabetic rats

The present investigation was carried out to evaluate the effect of N-benzoyl-D-phenylalanine (NBDP) and metformin on blood glucose, plasma insulin, and on the fatty acid composition of total lipids in the livers and kidneys of control and experimental diabetic rats. When compared with nondiabetic control rats, neonatal streptozotocin (nSTZ) diabetic rats showed a significant increase in blood glucose and decreased plasma insulin. Analysis of fatty acids revealed a significant increase in the concentration of palmitic, stearic, and oleic acids in liver and kidney, whereas linolenic and arachidonic acids were significantly decreased. In diabetic rats, the oral administration of combined NBDP/metformin for 6 wk decreased the high concentrations of palmitic, stearic, and oleic acids and elevated the low levels of linolenic and arachidonic acids. The results suggest that the NBDP/metformin combination exhibits both antidiabetic and antihyperlipidemic effects in nSTZ diabetic rats and prevents the fatty acid changes produced during diabetes.     

Nitrogen dioxide: no influence on allergic sensitization in an intranasal mouse model with ovalbumin and diesel exhaust particles

The role of traffic-related air pollution in the development of allergic diseases is still unclear. We therefore investigated if NO₂, an important constituent of traffic-related air pollution, promotes allergic sensitization to the allergen ovalbumin (OVA). We also examined if NO₂ influenced the allergy adjuvant activity of diesel exhaust particles (DEP). For this purpose, mice were exposed intranasally to OVA with or without DEP present, immediately followed by exposure to NO₂ (5 or 25 parts per million [ppm]) or room air for 4?h in whole body exposure chambers. Eighteen hours after the last of three exposures, the lungs of half of the animals were lavaged with saline and markers of lung damage and lung inflammation in the bronchoalveolar lavage fluid (BALF) were measured. Three weeks later, after intranasal booster immunizations with OVA, the levels of OVA-specific IgE and IgG2a antibodies in serum were determined. Both NO₂ (25?ppm) and DEP gave lung damage, measured as increased total protein concentration in BALF, whereas only NO₂ seemed to stimulate release of the proinflammatory cytokine tumor necrosis factor alpha (TNF-α). In contrast, only DEP significantly increased the number of neutrophils. Furthermore, DEP in combination with OVA stimulated the production of serum allergen-specific IgE antibodies. NO₂, however, neither increased the production of allergen-specific IgE antibodies, nor influenced the IgE adjuvant activity of DEP. Thus, based on our findings, NO₂ seems to be of less importance than combustion particles in the development of allergic diseases after exposure to traffic-related air pollution.     

Pharmacological and Morphological Changes in Rat Mast Cells Exposed to Nitrogen Dioxide in Vitro

Abstract

In spite of important roles that mast cells play in inflammation, immunoregulation, and immediate hypersensitivity, the effects of environmental pollutants on mast-cell activity are little known. Our purpose in this study is to investigate the effects of in vitro exposure to nitrogen dioxide (NO₂) on histamine and O-hexosaminidase release from rat peritoneal mast cells (PMC). Purified PMC were exposed to 5 and 20 ppm NO₂ in vitro for 30 or 60 min. The numbers of PMC decreased significantly after 60 min of exposure to 20 ppm NO, but not after 30 min of exposure to NO₂ Significant spontaneous histamine release was not observed in the 30-min exposure. However histamine release by compound 48/80 or substance P from NO₂-exposed mast cells was markedly inhibited compared with that from the controls, but the inhibition was not observed in histamine release by ionophore A23187. β-Hexosaminidase release by substance P from NO₂-exposed mast cells was significantly inhibited. Morphological observation showed the effect on the cell surface of Norexposed mast cells. These results suggest that NO₂ may affect mast-cell activity through damage to its membrane.     

Phospholipids in the liver of the pregnant rat: changes in fatty acid content and composition

Pregnancy in the rat was associated with changes in hepatic phospholipids. All changes returned to the prepregnancy levels 2 to 3 weeks postpartum. The total phospholipid content was reduced significantly, mainly representing a reduction of phosphatidylcholine, -ethanolamine, and lysophosphatidylcholine fractions. Hepatic fatty acid content was also reduced and the composition was modified since both saturated and unsaturated acyl components were decreased with more pronounced changes in unsaturated acids. Total liver saturated fatty acids with 14 to 16 carbon atoms remained unaltered; stearic acid was reduced and arachidic and lignoceric acids were elevated. Among unsaturated fatty acids, palmitoleic, oleic, eicosatrienoic, arachidonic, eicosapentaenoic, and docosapentaenoic were decreased, docosatrienoic and docosahexaenoic were raised, whereas eicosaenoic and eicosadienoic did not change. In the phosphatidylcholine and -ethanolamine fractions, unsaturated acyl components also showed significant reduction. By and large they reflected the fatty acid changes occurring in total liver with the exception of the docosahexaenoic acid which was diminished in both fractions. The overall effect of pregnancy thus indicated a modification in unsaturated fatty acid content leading to the construction of less fluid membranes which may be responsible for the reduced enzyme activity of the endoplasmic reticulum.     

Omega-3 fatty acids induce Ca2+ mobilization responses in human colon epithelial cell lines endogenously expressing FFA4

Aim:

Free fatty acid receptor 4 (FFA4; formerly known as GPR120) is the G protein-coupled receptor (GPCR) for omega-3 polyunsaturated fatty acids. FFA4 has been found to express in the small intestines and colons of mice and humans. In this study we investigate the effects of omega-3 polyunsaturated fatty acids on FFA4 in human colon epithelial cells in vitro.

Methods:

HCT116 and HT-29 human colon epithelial cell lines endogenously expressing FFA4 were used. Intracellular Ca²⁺ concentration ([Ca²⁺]_i) was measured in fura 2-AM-loaded cells with fluorescence spectrophotometry. RT-PCR and immunohistochemistry were used to detect FFA4.

Results:

Ten to 100 μmol/L of omega-3 polyunsaturated fatty acids α-linolenic acid (αLA) or eicosapentaenoic acid (EPA) induced dose-dependent [Ca²⁺]_i increase in HCT116 and HT-29 cells, whereas docosahexaenoic acid (DHA) had no effect. In addition, the omega-6 fatty acids linoleic acid and γ-linoleic acid also dose-dependently increase [Ca²⁺]_i, but the mono-unsaturated fatty acid oleic acid and saturated fatty acids such as stearic acid and palmitic acid had no effect. In HCT116 and HT-29 cells, the αLA-induced [Ca²⁺]_i increase was partially inhibited by pretreatment with EGTA, phospholipase C inhibitor edelfosine, cADPR inhibitors 8-bro-cADPR or DAB, and abolished by pretreatment with Ca²⁺ATPase inhibitor thapsigargin, but was not affected by G_i/o protein inhibitor PTX or IP₃R inhibitor 2-APB.

Conclusion:

Omega-3 and omega-6 long-chain polyunsaturated fatty acids (C18-20) induce Ca²⁺ mobilization responses in human colonic epithelial cells in vitro through activation of FFA4 and PTX-insensitive G_i/o protein, followed by Ca²⁺ release from thapsigargin-sensitive Ca²⁺ stores and Ca²⁺ influx across the plasma membrane.     

Effects of C18 Fatty Acids on Intracellular Ca2+ Mobilization and Histamine Release in RBL-2H3 Cells

To investigate the underlying mechanisms of C18 fatty acids (stearic acid, oleic acid, linoleic acid and α-linolenic acid) on mast cells, we measured the effect of C18 fatty acids on intracellular Ca²⁺ mobilization and histamine release in RBL-2H3 mast cells. Stearic acid rapidly increased initial peak of intracellular Ca²⁺ mobilization, whereas linoleic acid and α-linolenic acid gradually increased this mobilization. In the absence of extracellular Ca²⁺, stearic acid (100 µM) did not cause any increase of intracellular Ca²⁺ mobilization. Both linoleic acid and α-linolenic acid increased intracellular Ca²⁺ mobilization, but the increase was smaller than that in the presence of extracellular Ca²⁺. These results suggest that C18 fatty acid-induced intracellular Ca²⁺ mobilization is mainly dependent on extracellular Ca²⁺ influx. Verapamil dose-dependently inhibited stearic acid-induced intracellular Ca²⁺ mobilization, but did not affect both linoleic acid and α-linolenic acid-induced intracellular Ca²⁺ mobilization. These data suggest that the underlying mechanism of stearic acid, linoleic acid and α-linolenic acid on intracellular Ca²⁺ mobilization may differ. Linoleic acid and α-linolenic acid significantly increased histamine release. Linoleic acid (C18:2: ω-6)-induced intracellular Ca²⁺ mobilization and histamine release were more prominent than α-linolenic acid (C18:3: ω-3). These data support the view that the intake of more α-linolenic acid than linoleic acid is useful in preventing inflammation.     

Pathophysiologic Responses of Sheep to Brief High-Level Nitrogen Dioxide Exposure

Abstract

The cardiopulmonary response to short-duration, high-concentration nitrogen dioxide (NO₂) exposure was examined in conscious domestic sheep (Ovis aries). Six intubated animals in each of 3 groups were given a 15-min exposure to either air (control) or approximately 700 or 500 ppm NO_2? Pulmonary and systemic hemody-namics, pulmonary mechanics, blood gases, and hematologic variables were measured immediately before and after exposure and at 1, 4, and 24 h after exposure. Minute ventilation was monitored during exposure, and a pulmonary histopathologic examination was performed 24 h postexposure. Negligible effects were observed in the control group. Exposure to 100 ppm NO₂ caused a modest increase in minute ventilation during exposure, and an increased number of leukocytes was found within interalveolar capillaries upon histologic examination. Exposure to 500 pprn NO₂ induced an immediate and profound lung irritant response characterized by an increase in lung resistance, respiratory rate, and minute ventilation. The exposure was marked by a statistically significant, but small, increase in methemoglobin concentration. Pulmonary function progressively deteriorated in the 24-h period following exposure to 500 ppm NO₂, and a significant arterial oxygen tension reduction and pulmonary artery pressure increase occurred at 24 h postexposure. Histologic examination after 500 ppm NO₂ revealed patchy lobular exudation and accumulation of leukocytes in both alveolar sacs and interalveolar capillaries.