Dataset Information

The oxidation and utilization of palmitate, stearate, oleate and acetate by the mammary gland of the fed goat in relation to their overall metabolism, and the role of plasma phospholipids and neutral lipids in milk-fat synthesis.

ABSTRACT: 1. Measurements were made of milk yield, mammary blood flow and arteriovenous differences of each plasma lipid fraction, and their specific radioactivities, during the infusion of [U-(14)C]stearate, [U-(14)C]oleate, [U-(14)C]palmitate and [1-(14)C]acetate into fed lactating goats. 2. Entry rates of fatty acids into the circulation were 4.2mg./min./kg. body wt. for acetate, and 0.18, 0.28 and 0.42mg./min./kg. for stearate, oleate and palmitate respectively. Acetate accounted for 23% of the total carbon dioxide produced by the whole animal, and contributed to the oxidative metabolism of the mammary gland to about the same extent. Corresponding values for each of the long-chain acids were less than 1%. 3. There were no significant arteriovenous differences of phospholipids, sterols or sterol esters, and their fatty acid composition showed no net changes during passage through the mammary gland. 4. There were large arteriovenous differences of plasma triglycerides, and their fatty acid composition showed marked changes across the gland. The proportions of palmitate and stearate fell, and that of oleate increased. 5. Arteriovenous differences of plasma free fatty acids (FFA) were small and variable, but a large fall in the specific radioactivity of each of the long-chain acids examined indicated substantial uptake of plasma FFA, accompanied by roughly equivalent FFA release from mammary tissue. The uptake of FFA was confirmed by the extensive transfer of radioactivity into milk. The FFA of milk were similar in composition and radioactivity to the milk triglyceride fatty acids, and quite unlike plasma FFA. 6. The formation of large amounts of oleic acid (18-21 mg./min.) from stearic acid was demonstrated. 7. During the terminal stages of the [(14)C]acetate infusion, milk triglyceride fatty acids of chain length C(4)-C(14) showed specific radioactivities that were 75-90% of that of blood acetate, and that of palmitate was roughly one-quarter of this value. Oleate and stearate were unlabelled. 8. The results confirmed that milk fatty acids of chain length C(4)-C(14) arise largely from blood acetate, and palmitate is derived partly from acetate and partly from plasma triglyceride, the latter fraction being almost the sole precursor of oleate and stearate.

SUBMITTER: Annison EF

PROVIDER: S-EPMC1270309 | biostudies-other | 1967 Mar

REPOSITORIES: biostudies-other

ACCESS DATA

Similar Datasets

Project description:The intracellular unbound drug concentration (Cu,cell) drives pharmacological and toxicological responses for targets inside cells. We have previously shown that Cu,cell is not always equal to extracellular unbound drug concentrations (e.g. plasma concentrations). However, the underlying mechanisms that drive cellular drug binding are poorly understood. The aim of this study was to evaluate drug binding to individual cellular components, such as neutral lipids (NL) and phospholipids (PL). The fibroblastic 3T3-L1 cell line was used as a cellular model. The cells were either used as wild-type (WT cells) or were treated with a differentiation cocktail that induced an adipocyte-like phenotype with large NL droplets (NL+PL+ cells), or treated with propranolol to induce accumulation of PL (PL+ cells). The three cell types were analysed for morphology, global protein expression, lipid content, cellular volume and lysosomal appearance. The cells were exposed to 23 drugs with diverse physicochemical properties, e.g., with regard to lipophilicity, charge, molecular weight and polar surface area. The cellular binding (fu,cell) and the total accumulation ratio (Kp) were measured and used to obtain the intracellular bioavailability (Fic)—defined as the unbound fraction of the drug concentration added to the cells that is available for intracellular target interaction. The NL+PL+ cells had an adipocyte-like morphology, whereas the PL+ were not visually distinguishable from WT cells. Analysis of the global proteome combined with pathway analysis supported the morphological appearances and confirmed the adipocyte-like phenotype of NL+PL+ cells and the normal morphology of PL+ cells. Fic was significantly altered in both treated cell types as compared to WT. A strong negative correlation between fu,cell and PL content in the cell homogenates was observed, whereas the increased NL content in the NL+PL+ cells did not increase binding further. The importance of PLs for drug binding was confirmed by affinities to beads coated with purified PLs. The NL+PL+ cells lacked acidic subcellular compartments (i.e., endo-lysosomal space), which further influenced the subcellular distribution of cationic drugs. In conclusion, our results suggest that PL content, but not NL content, is a major determinant of drug binding in cells, and that PL beads may constitute a simple alternative to more cumbersome cell distribution studies.

Project description:1. Rates of entry and oxidation of a range of metabolites have been measured in tracheostomized sheep (diet, 800g. of lucerne chaff and 100g. of maize/day) by combining isotope-dilution techniques with the continuous measurement of total respiratory gas exchange, and (14)CO(2) production during the intravenous or intraruminal infusion of (14)C-labelled substrates. 2. Mean entry rates in fed and starved (24hr.) sheep respectively, expressed as mg./min./kg. body wt.(0.75), were: glucose, 5.0 (range 4.8-5.1, 2 observations) and 3.8 (3.2-4.2, 4); acetate, 10.8 (9.1-13.5, 4) and 5.8 (1); d(-)-beta-hydroxybutyrate, 1.4 (1) and 1.5 (0.8-2.4, 4); palmitate, oleate and stearate (starved sheep only) 1.0 (0.6-1.9, 7), 0.9 (0.2-1.6, 10) and 0.9 (0.5-1.1, 11) respectively. 3. Production rates of propionate and butyrate in continuously feeding sheep were 6.4 (4.7-8.3, 4) and 4.3 (3.4-6.1, 4) mg./min./kg.(0.75) respectively, and in starved (24hr.) sheep were 2.5 (2.2-2.9, 2) and 1.0 (0.8-1.2, 2) mg./min./kg.(0.75) respectively. 4. Calculated terminal values for the specific radioactivity of respiratory (14)CO(2) during measurements of entry rates and production rates were used to calculate the contributions of individual substrates to overall oxidative metabolism. Mean values for fed and starved sheep respectively were: glucose, 9.1 (8.6-9.6, 2) and 11.2 (5.9-15.1, 4)%; acetate, 31.6 (26.8-38.1, 4) and 22.1 (1)%; d(-)-beta-hydroxybutyrate, 10.4 (1) and 4.8 (1.9-7.7, 4)%; propionate, 23.0 (13.8-29.9, 4) and 7.1 (6.8-7.4, 2)%; butyrate, 16.5 (13.7-20.5, 4) and 5.3 (5.2-5.3, 2)%; palmitate, oleate and stearate (starved sheep only), 4.7 (2.0-7.7, 7), 4.0 (1.2-6.6, 10) and 4.4 (3.8-5.8, 9)% respectively. The sum of these values for individual substrates in fed and starved sheep, excluding that of beta-hydroxybutyrate and after correction of the glucose value for the known interrelations of this substrate with propionate, accounted for 76% and 58% respectively of total production of carbon dioxide. 5. Calculations based on the proportion of substrate entry directly oxidized indicated that the substrates studied accounted for 63% (fed sheep) and 43% (starved sheep) of total energy expenditure measured by oxygen uptake. The contribution of beta-hydroxybutyrate was excluded, and corrections were made for glucose-propionate interrelations, and for the different rates of oxidation of the methyl and carboxyl fragments of acetate. 6. The present results have been combined with those obtained earlier in this Laboratory to examine the relationships between rates of substrate entry and oxidation, and concentrations of substrate in blood. Rates of entry of acetate, glucose, d(-)-beta-hydroxybutyrate, palmitate and oleate (but not stearate) were well correlated with concentration in blood, and substrate contribution to production of carbon dioxide showed a similar correlation to blood concentration, except with glucose. 7. It was concluded that the general technique is of potential value in providing valid quantitative parameters of animal metabolism.

Project description:Aims/hypothesisEnergy-dense nutrition generally induces insulin resistance, but dietary composition may differently affect glucose metabolism. This study investigated initial effects of monounsaturated vs saturated lipid meals on basal and insulin-stimulated myocellular glucose metabolism and insulin signalling.MethodsIn a randomised crossover study, 16 lean metabolically healthy volunteers received single meals containing safflower oil (SAF), palm oil (PAL) or vehicle (VCL). Whole-body glucose metabolism was assessed from glucose disposal (Rd) before and during hyperinsulinaemic-euglycaemic clamps with D-[6,6-2H2]glucose. In serial skeletal muscle biopsies, subcellular lipid metabolites and insulin signalling were measured before and after meals.ResultsSAF and PAL raised plasma oleate, but only PAL significantly increased plasma palmitate concentrations. SAF and PAL increased myocellular diacylglycerol and activated protein kinase C (PKC) isoform θ (p < 0.05) but only PAL activated PKCɛ. Moreover, PAL led to increased myocellular ceramides along with stimulated PKCζ translocation (p < 0.05 vs SAF). During clamp, SAF and PAL both decreased insulin-stimulated Rd (p < 0.05 vs VCL), but non-oxidative glucose disposal was lower after PAL compared with SAF (p < 0.05). Muscle serine1101-phosphorylation of IRS-1 was increased upon SAF and PAL consumption (p < 0.05), whereas PAL decreased serine473-phosphorylation of Akt more than SAF (p < 0.05).Conclusions/interpretationLipid-induced myocellular insulin resistance is likely more pronounced with palmitate than with oleate and is associated with PKC isoforms activation and inhibitory insulin signalling.Trial registrationClinicalTrials.gov .NCT01736202.FundingGerman Federal Ministry of Health, Ministry of Culture and Science of the State North Rhine-Westphalia, German Federal Ministry of Education and Research, European Regional Development Fund, German Research Foundation, German Center for Diabetes Research.

Dataset Information

The oxidation and utilization of palmitate, stearate, oleate and acetate by the mammary gland of the fed goat in relation to their overall metabolism, and the role of plasma phospholipids and neutral lipids in milk-fat synthesis.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets