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Gas chromatography-mass spectrometry of cis-9,10-epoxyoctadecanoic acid (cis-EODA). I. Direct evidence for cis-EODA formation from oleic acid oxidation by liver microsomes and isolated hepatocytes.

Oleic acid, cis-9-octadecenoic acid, is the major fatty acid in mammals. Its oxide, cis-9,10-epoxyoctadecanoic acid (cis-EODA), has been identified in blood and urine of humans, its origin is, however, still unknown. Lipid peroxidation and enzyme-catalyzed epoxidation of oleic acid are two possible sources. In the present article, we investigated by HPLC and GC-MS whether cis-EODA is formed enzymatically from oleic acid by the cytochrome P450 (CYP) system. Oleic acid, cis-EODA and its hydratation product threo-9,10-dihydroxyoctadecanoic acid (threo-DiHODA) were quantitated by HPLC as their p-bromophenacyl esters. For structure elucidation by GC-MS, the pentafluorobenzyl (PFB) esters of these compounds were isolated by HPLC and converted to their trimethylsilyl ether derivatives. Liver microsomes of rats, rabbits and humans oxidized oleic acid into cis-EODA. This is the first direct evidence for the enzymatic formation of cis-EODA from oleic acid. The epoxidation of oleic acid was found to depend on CYP, NADPH+H(+), and O(2). cis-EODA was measurable in incubates of liver microsomes for up to 30 min of incubation. Maximum cis-EODA concentrations were reached after 5-7 min of incubation and found to depend upon oleic acid concentration. Isolated rat hepatocytes hydratated cis-EODA into threo-DiHODA which was further converted to unknown metabolites. However, from incubation of oleic acid with these cells we could not detect threo-DiHODA or cis-EODA. Our study suggests that circulating and excretory cis-EODA may originate, at least in part, from CYP-catalyzed epoxidation of oleic acid. GC-MS of intact cis-EODA as its PFB ester in the negative-ion chemical ionization mode should be useful in investigating the physiological role of cis-EODA in man.

Animals↗

Ileostomy output and bile acid excretion after intraduodenal administration of oleic acid.

BACKGROUND: Ileostomy output and small-intestinal transport are regulated by complex mechanisms, which the present study aimed to further elucidate. METHODS: The time-related ileostomy output and bile acid excretion after intraduodenal administration of a fat solution (oleic acid, 3.5 g) was studied in 29 ileostomy patients. Eighteen patients had the entire small bowel preserved (group I), whereas 11 had various lengths of the ileum resected or bypassed (group II). RESULTS: Intraduodenal fat administration resulted in a prompt and significant increase in ileostomy output in both groups. The accumulated 2-h output after fat administration amounted to 60% of the normal 24-h output in group I and 30% in group II. A marked increase in bile acid excretion preceded the flow response. The fat-induced response was abolished by administration of cholestyramine. CONCLUSIONS: Bile acids seem to have important regulatory effects with regard to secretion/absorption and transport of small-bowel contents, affecting ileostomy output, with clinical implications in many patients.

Bile Acids and Salts↗

A genomic explanation connecting "Mediterranean diet", olive oil and cancer: oleic acid, the main monounsaturated fatty acid of olive oil, induces formation of inhibitory "PEA3 transcription factor-PEA3 DNA binding site" complexes at the Her-2/neu (erbB-2) oncogene promoter in breast, ovarian and stomach cancer cells.

Olive oil is an integral ingredient of the "Mediterranean diet" and accumulating evidence suggests that it may have a potential role in lowering risk of several cancers. We recently hypothesized that the anti-cancer actions of olive oil may relate to its monounsaturated fatty acid (MUFA) oleic acid (OA; 18:1n-9) content to specifically regulate oncogenes. In this study, transient transfection experiments with human Her-2/neu promoter-driven luciferase gene established the ability of OA to specifically repress the transcriptional activity of Her-2/neu gene. Gene repression was seen in tumour-derived cell lines with Her-2/neu gene amplification and overexpression, including SK-Br3 (56% reduction), SK-OV3 (75% reduction) and NCI-N87 (55% reduction) breast, ovarian and stomach cancer cell lines, respectively. Also marginal decreases in promoter activity were observed in cancer cells expressing physiological levels of Her-2/neu (20% reduction in MCF-7 breast cancer cells). Remarkably, OA treatment in Her-2/neu-overexpressing cancer cells was found to induce up-regulation of the Ets protein polyomavirus enhancer activator 3 (PEA3), a transcriptional repressor of Her-2/neu promoter. Also, an intact PEA3 DNA-binding-site at endogenous Her-2/neu gene promoter was essential for OA-induced repression of this gene. Moreover, OA treatment failed to decrease Her-2/neu protein levels in MCF-7/Her2-18 transfectants, which stably express full-length human Her-2/neu cDNA controlled by a SV40 viral promoter. OA-induced transcriptional repression of Her-2/neu through the action of PEA3 protein at the promoter level may represent a novel mechanism linking "Mediterranean diet" and cancer.

Breast Neoplasms↗

Lipoprotein-cholesterol responses in healthy infants fed defined diets from ages 1 to 12 months: comparison of diets predominant in oleic acid versus linoleic acid, with parallel observations in infants fed a human milk-based diet.

A prospective study in healthy infants predefining both diet fatty acid and cholesterol, from birth to age 1 year, compared response of cholesterol fractions in three groups: random assignment to 1) monounsaturated-(Hi-Mono) (n = 20), or 2) polyunsaturated-(Hi-Poly) (n = 22) fatty acid-enriched diets, or 3) non-randomized selection to breast feeding (Human Milk) (n = 25). In each group, designated weaning foods and supplements maintained fatty acid and cholesterol intake similar to that of each group's defined formulas, with long-term compliance confirmed by plasma phospholipid fatty acid concentrations. By 12 months, total cholesterol was significantly lower in the Hi-Poly group compared to either of the other groups (P < 0.05). Low density lipoprotein (LDL)- and high density lipoprotein (HDL)-cholesterol concentrations were significantly lower by 12 months in the Hi-Poly group, compared to the Hi-Mono groups. However, at the earlier 4-month interval, total cholesterol and LDL-cholesterol in both Hi-Mono and Hi-Poly groups were not different from each other, although each was significantly lower than the parallel Human Milk-group (P < 0.05). The Hi-Mono group increased gradually in total and LDL-cholesterol such that, after 12 months' feedings, all lipid fractions of this Hi-Mono group were no different from those of the Human Milk group. In independent group comparisons, there were no significant differences in HDL-cholesterol concentrations after 4 and 9 months on these diets. Independent of diet, HDL-cholesterol showed a falling trend as an overall time-effect across all groups (P < 0.001). These data suggest that prolonged feeding of a diet enriched in polyunsaturated acids in early infancy has a significant cholesterol-lowering effect compared to monounsaturates. These differences in total, LDL-, and HDL-cholesterol plasma concentrations between polyunsaturates and monounsaturates were not significantly evident until feedings had continued for a year.

Cholesterol, HDL↗

Direct vascular antiatherogenic effects of oleic acid: a clue to the cardioprotective effects of the Mediterranean diet.

Atherosclerosis, the main cause of ischemic heart disease, is a process with relevant inflammatory components, in which LDL-cholesterol, largely emphasized in the last years as a "causal" factor following the improvement in prognosis with cholesterol-lowering agents, is only one of the culprits. Despite the use of new cholesterol-lowering drugs, atherosclerotic vascular disease will likely continue to be the main cause of death in Western countries. Furthermore, the statistical relationship between cholesterol and cardiovascular mortality only explains a relatively minor component of differences in mortality among diverse countries. For these reasons, the interest in preventive approaches complementary or alternative to cholesterol reduction should be one of the main objectives of cardiovascular research in the years to come. Already in the '70s the very low incidence of atherosclerotic diseases in Mediterranean countries (Greece and Southern Italy) and the importance of the "dietary factor" in such protection were noticed. Diets for people in these countries are, among other components, very rich in oleic acid, the main constituent of olive oil, with about 29% of daily caloric intake derived from monounsaturated fatty acids. Oleic acid, besides exerting relatively minor effects on the quantitative and qualitative regulation of cholesterol levels, appears to interfere directly with the inflammatory response that characterizes early atherogenesis. The endothelial expression of adhesion molecules for circulating monocytes, induced by inflammatory cytokines, minimally oxidized LDL and the advanced glycation end-products present in diabetes, substantially contributes to the onset and early progression of atherosclerosis. In an in vitro model of early atherogenesis based on cultured endothelial cells stimulated by cytokines, we observed that the incorporation of oleic acid in total cell lipids--mostly at the expenses of saturated fatty acids--decreases the expression of several endothelial leukocyte adhesion molecules, among which vascular cell adhesion molecule-1, involved in the selective monocyte recruitment in the arterial intima. Oleic acid also determines a parallel reduction in messenger RNA for this molecule, interfering with the activation of the most important transcription factor controlling endothelial activation, nuclear factor-kappa B. Thus, possibly in concert with other more highly unsaturated fatty acids, oleic acid may contribute to the prevention of atherosclerosis also through a modulation of gene expression for endothelial leukocyte adhesion molecules. This series of investigations emphasizes the possibility of preventive interventions in atherosclerosis based on the modulation of vascular response to classical "triggers" (cholesterol, advanced glycation end-products of diabetes), an intervention strategy fundamentally different from--and thereby complementary to--those now more in fashion.

Arteriosclerosis↗

Role of cholecystokinin in the anorexia produced by duodenal delivery of oleic acid in rats.

To assess the importance of triglyceride digestion products in producing satiety, we determined the effects of duodenal infusions of triolein, oleic acid, and oleic acid plus monoolein on meal patterns in ad libitum-feeding rats. Oleic acid and oleic acid plus monoolein inhibited feeding similarly; triolein's effect was delayed and fourfold less potent. We then used the type A cholecystokinin (CCK-A)-receptor antagonist devazepide to assess the importance of CCK in mediating the anorexia produced by oleic acid. Oleic acid (at 320, 440, and 640 mumol/h) inhibited 3-h intake dose dependently by 32, 56, and 75%, respectively. Devazepide (1 or 2 mg/kg) blocked the responses to the 320 mumol/h dose, but had little if any effect on responses to the larger doses. Devazepide (1 mg/kg) did block anorexic responses to 3-h cholecystokinin octapeptide infusions (3 and 10 nmol.kg-1.h-1 iv) that inhibited 3-h intake by 25 and 65%, respectively. Our results suggest that the satiety response to triolein is produced by the products of triolein digestion and that CCK plays a significant, indispensable role in mediating the satiety response to duodenal delivery of small but not large loads of oleic acid.

Animals↗

The inhibition of platelet-activating factor-induced platelet activation by oleic acid is associated with a decrease in polyphosphoinositide metabolism.

In an earlier study (Miwa, M., Hill, C., Kumar, R., Sugatani, J., Olson, M. S., and Hanahan, D. J. (1987) J. Biol. Chem. 262, 527-530) it was shown that an inhibitor of platelet-activating factor (PAF), a powerful endogenous mediator of platelet aggregation, was present in freeze-clamped perfused livers. Subsequently, we determined that this substance was a mixture of unsaturated free fatty acids (FFA). Among these FFA, oleic acid between 10 and 100 microM was found to be a potent inhibitor of PAF-induced platelet aggregation and serotonin secretion. Consequently, in order to understand the molecular mechanism of oleic acid action, we investigated the effects of this FFA on several biochemical events associated with platelet aggregation induced by PAF. The effect of oleic acid and/or PAF on the level of [32P]phosphatidylinositol 4-phosphate (PIP) and [32P]phosphatidylinositol 4,5-bisphosphate (PIP2) was examined by using platelets labeled with [32P]phosphate. Oleic acid induced a dose-dependent decrease in the levels of [32P]PIP and [32P]PIP2; a maximal decrease in [32P]PIP and [32P]PIP2 of approximately 50 and 25%, respectively, was observed within seconds after the addition of 20 microM oleic acid and persisted for at least 15 min. Oleic acid did not induce the formation of [3H]inositol phosphates in platelets prelabeled with [3H]inositol, suggesting that the decrease in [32P]PIP and [32P]PIP2 was not due to a stimulation of phospholipase C. In contrast to oleic acid, PAF induced a dose-dependent increase in the [32P]PIP level, reaching a maximum of approximately 200% 3 min after the addition of 1 nM PAF to the platelets. This increase in [32P]PIP was accompanied by platelet aggregation and secretion, and a close correlation was established between the [32P]PIP level and the degree of aggregation. Oleic acid and PAF, when added together to the platelets, interacted by affecting the level of [32P]PIP and [32P]PIP2 in an opposite way since the decrease in the level of [32P]PIP and [32P] PIP2 induced by oleic acid was partially reversed by an excess of PAF. The decrease in the levels of [32P] PIP and [32P]PIP2 caused by oleic acid was associated with an inhibition of platelet aggregation induced by PAF. Interestingly, oleic acid did not block [3H]PAF binding to platelets but inhibited the PAF-induced phosphorylation of platelet proteins of 20 kDa and 40 kDa. These results suggest that inhibition of the PAF response by oleic acid may be at one of the steps in the signal transduction.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

Deterioration of goat spermatozoa in skimmed milk-based extenders as a result of oleic acid released by the bulbourethral lipase BUSgp60.

The aim of the present study was to elucidate the mode of action of goat bulbourethral lipase (BUSgp60 lipase) previously identified as responsible for the deterioration of goat sperm viability in skimmed milk-based extenders. Milk fractions were purified by micro- and ultrafiltration and characterized by SDS-PAGE, thin layer chromatography, triglyceride quantitative analysis and by their ability to potentiate the lipase and the sperm-deteriorating activity of the bulbourethral lipase. Components in both the phosphocaseinate and soluble whey protein fractions enhanced the lipase activity of BUSgp60 but only the phosphocaseinate fraction, which contains triglycerides, promoted deterioration of spermatozoa in the presence of bulbourethral gland secretion. These data suggest that the sperm-deteriorating effect of bulbourethral gland secretion is due to the catalysis of triglyceride hydrolysis, and that proteins increase this activity. BUSgp60 hydrolysed milk triglycerides and triolein very effectively, and its lipase activity was enhanced by several highly purified milk proteins. The major cis-unsaturated fatty acid from milk (oleic acid) but not the major saturated fatty acid (palmitic acid) exhibited dose-dependent detrimental effects on goat spermatozoa. Therefore, the catalysis of oleic acid formation from residual milk triglycerides by BUSgp60 appears responsible for the deterioration of goat spermatozoa when unwashed semen is diluted in skimmed milk-based extenders. The precise mechanism of action of oleic acid remains to be elucidated but the drawbacks of washing buck semen might be avoided by inhibiting BUSgp60 or by depriving it of substrate.

Analysis of Variance↗

[Decanoic acid, new precursor for in vitro biosynthesis of oleic acid by a plant subcellular fraction].

Various membraneous fractions prepared from a cauliflower homogenate synthesize radioactive oleic acid when they are incubated in a 14C-decanolate solution. The more active fraction is formed of vesicles sedimenting at 30,000 g x 20 mn (heavy microsomes). The labelled precursor is transformed by this fraction mainly into oleic acid and hydroxyacids. ATP, NADPH, CoA and oxygen are required for these reactions. Labelled fatty acids, longer than lauric and (i.e. 14C-myristic, 14C-palmitic and 14C-stearic acids) are not transformed into oleic acid by the subcellular fraction studied in this paper.

Adenosine Triphosphate↗

Mechanisms of fatty acid effects on sarcoplasmic reticulum. III. The effects of palmitic and oleic acids on sarcoplasmic reticulum function--a model for fatty acid membrane interactions.

The mechanism by which palmitic and oleic acids modify calcium sequestration by sarcoplasmic reticulum vesicles was investigated by examining the effects of these fatty acids on calcium-dependent ATPase activity, on the phosphoenzyme intermediates found during calcium sequestration reactions, and on passive membrane permeability to calcium. The calcium sequestered in the presence of these fatty acids was also characterized by determining the amount exchangeable with the extravesicular pool or released by the ionophore A23187. In the presence of 50 microM ATP, 18 microM palmitic acid enhanced and 18 microM oleic acid inhibited calcium sequestration, whereas both fatty acids stimulated ATPase activity. Neither fatty acid had significant effects on the amount or distribution of the phosphoenzyme formed during the calcium transport reaction. Palmitic acid stimulated calcium sequestration only when ATP was present. Oleic acid caused the release of a portion of the accumulated calcium during ATP-supported calcium sequestration and also enhanced the release observed in ATP-depleted reactions. A portion of the calcium sequestered in the presence of palmitic acid appears to be incorporated into a nonexchangeable and ionophore-insensitive calcium pool, although the latter was estimated to be considerably larger than the nonexchangeable pool. These data support the hypothesis that oleic acid inhibits calcium sequestration by increasing membrane permeability to calcium, whereas palmitic acid appears to stimulate calcium sequestration by interacting with a portion of the calcium within the vesicles to form a separate, poorly exchangeable calcium pool.

Adenosine Triphosphate↗

Adsorption of oleic acid at sillimanite/water interface.

The interaction of oleic acid at sillimanite-water interface was studied by adsorption, FT-IR, and zeta potential measurements. The isoelectric point (IEP) of sillimanite obtained at pH 8.0 was found to shift in the presence of oleic acid. This shift in IEP was attributed to chemisorption of oleic acid on sillimanite. Adsorption experiments were conducted at pH 8.0, where the sillimanite surface is neutral. The adsorption isotherm exhibited a plateau around 5 micromol/m2 that correspond to a monolayer formation. Adsorption of oleic acid on sillimanite, alumina, and aluminum hydroxide was studied by FT-IR. Chemisorption of oleic acid on the above substrates was confirmed by FT-IR studies. Hydroxylation of mineral surface was found to be essential for the adsorption of oleic acid molecules. These surface hydroxyl sites were observed to facilitate deprotonation of oleic acid and its subsequent adsorption. Thus protons from oleic acid react with surface hydroxyl groups and form water molecules. Based on the experimental results, the mechanism of oleic acid adsorption on mineral substrate was proposed. Free energy of adsorption was estimated using the Stern-Graham equation for a sillimanite-oleate system.

Journal Article↗

Opposite effects on cholesterol metabolism and their mechanisms induced by dietary oleic acid and palmitic acid in hamsters.

The effects of dietary oleic acid on cholesterol metabolism were investigated and compared with those of palmitic acid in hamsters. Addition of 5% oleic acid to a 0.1% cholesterol-supplemented diet decreased plasma total cholesterol, very low density lipoprotein (VLDL) cholesterol, and low density lipoprotein (LDL) cholesterol, increased hepatic LDL receptor activity, and decreased plasma cholesteryl ester transfer protein (CETP) activity in comparison with 0.1% cholesterol alone. In contrast, addition of 5% palmitic acid to a 0.1% cholesterol-supplemented diet increased total cholesterol and LDL-cholesterol, increased plasma CETP activity, and suppressed hepatic LDL receptor activity to a greater extent than 0.1% cholesterol alone. Neither oleic acid nor palmitic acid altered hepatic microsomal 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase activity, but oleic acid increased hepatic microsomal cholesterol 7 alpha-hydroxylase activity. These results suggest that dietary oleic acid inhibits the increases in total, VLDL-, and LDL-cholesterol induced by dietary cholesterol by preventing both LDL receptor suppression and increased CETP activity, whereas dietary palmitic acid augments the cholesterol-induced increases in total and LDL-cholesterol by both further suppression of LDL receptor activity and further stimulation of CETP activity.

Animals↗

Crystal structure of axolotl (Ambystoma mexicanum) liver bile acid-binding protein bound to cholic and oleic acid.

The family of the liver bile acid-binding proteins (L-BABPs), formerly called liver basic fatty acid-binding proteins (Lb-FABPs) shares fold and sequence similarity with the paralogous liver fatty acid-binding proteins (L-FABPs) but has a different stoichiometry and specificity of ligand binding. This article describes the first X-ray structure of a member of the L-BABP family, axolotl (Ambystoma mexicanum) L-BABP, bound to two different ligands: cholic and oleic acid. The protein binds one molecule of oleic acid in a position that is significantly different from that of either of the two molecules that bind to rat liver FABP. The stoichiometry of binding of cholate is of two ligands per protein molecule, as observed in chicken L-BABP. The cholate molecule that binds buried most deeply into the internal cavity overlaps well with the analogous bound to chicken L-BABP, whereas the second molecule, which interacts with the first only through hydrophobic contacts, is more external and exposed to the solvent.

Ambystoma↗

Transfer of oleic acid between albumin and phospholipid vesicles.

The net transfer of oleic acid between egg phosphatidylcholine unilamellar vesicles and bovine serum albumin has been monitored by 13C NMR spectroscopy and 90% isotopically substituted [1-13C]oleic acid. The carboxyl chemical shifts of oleic acid bound to albumin were different from those for oleic acid in phospholipid vesicles. Therefore, in mixtures of donor particles (vesicles or albumin with oleic acid) and acceptor particles (fatty acid-free albumin or vesicles), the equilibrium distribution of oleic acid was determined from chemical shift and peak intensity data without separation of donor and acceptor particles. In a system containing equal masses of albumin and phospholipid and a stoichiometry of 4-5 mol of oleic acid per mol of albumin, the oleic acid distribution was pH dependent, with greater than or equal to 80% of the oleic acid associated with albumin at pH 7.4; association was greater than or equal to 90% at pH 8.0. Decreasing the pH below 7.4 markedly decreased the proportion of fatty acid bound to albumin; at pH 5.4, less than or equal to 10% of the oleic acid was bound to albumin and greater than 90% was associated with vesicles. The distribution was reversible with pH and was independent of whether vesicles or albumin acted as a donor. These data suggest that pH may strongly influence the partitioning of fatty acid between cellular membranes and albumin. The 13C NMR method is also advantageous because it provides information about the structural environments of oleic acid bound to albumin or phospholipid, the ionization state of oleic acid in each environment, and the structural integrity of the vesicles. In addition, minimum and maximum limits for the exchange rates of oleic acid among different environments were obtained from the NMR data.

Fatty Acids↗

Effects of oleic acid and its congeners, elaidic and stearic acids, on the structural properties of phosphatidylethanolamine membranes.

Fatty acid derivatives are abundant in biological membranes, mainly as components of phospholipids and cholesterol esters. Their presence, free or bound to phospholipids, modulates the lipid membrane behavior. The present study shows the differential influence of the C-18 fatty acids (FAs), oleic, elaidic, and stearic acids on the structural properties of phosphatidylethanolamine (PE). X-ray diffraction of PE-FA systems demonstrated that oleic acid (OA) produced important concentration-dependent alterations of the lipid membrane structure: it induced reductions of up to 20-23 degrees C in the lamellar-to-hexagonal transition temperature of 1-palmitoyl-2-oleoyl PE and dielaidoyl PE and regulated the dimensions of the hexagonal lattice. In contrast, elaidic and stearic acids did not markedly alter the phospholipid mesomorphism. The above effects were attributed to the different "molecular shape" of OA (with a kink at the middle of the molecule) with respect to their congeners, elaidic and stearic acids. The effects of free fatty acids (FFAs) on membrane structure are relevant for several reasons: i) some biological membranes contain very high levels of FFAs. ii) Mediterranean diets with high OA intake have been shown to exert protective effects against tumoral and hypertensive pathologies. iii) FFA derivatives have been developed as antitumoral and antihypertensive drugs.

Cell Membrane↗

Acid-base status affects gas exchange in canine oleic acid pulmonary edema.

The effects of acidosis and alkalosis on pulmonary gas exchange were studied in 32 pentobarbital sodium-anesthetized intact dogs after induction of oleic acid (0.06 ml/kg) pulmonary edema. Gas exchange was assessed at constant ventilation and constant cardiac output, by venous admixture calculations and by intrapulmonary shunt measurements using the sulfur hexafluoride (SF6) method. Metabolic acidosis (pH 7.20) and alkalosis (pH 7.60) were induced with HCl and Carbicarb (isosmolar Na2CO3 and NaHCO3), respectively. Hypercapnia was induced by adding inspiratory CO2, whereas pH was allowed to change (respiratory acidosis, pH 7.20) or maintained constant (isolated hypercapnia). Mean intrapulmonary shunt and pulmonary arterial minus wedge pressure difference, respectively, changed from 44 to 33% (P less than 0.05) and from 9 to 10 mmHg (P greater than 0.05) in metabolic acidosis, from 44 to 62% (P less than 0.001) and from 12 to 8 mmHg (P less than 0.01) in metabolic alkalosis, from 40 to 42% (P greater than 0.05) and from 13 to 16 mmHg (P less than 0.05) in respiratory acidosis, from 42 to 52% (P less than 0.05) and from 8 to 12 mmHg (P less than 0.01) in isolated hypercapnia. These results indicate that acidosis, alkalosis, and hypercapnia markedly influence pulmonary gas exchange and/or pulmonary hemodynamics in dogs with oleic acid pulmonary edema.

Acidosis↗