Propionate metabolism and its regulation by fatty acids in ovine hepatocytes

Faulkner, Anne; Pollock, Helen T.

doi:10.1016/0305-0491(86)90123-9

Cited by 15 publications

(15 citation statements)

References 11 publications

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“…Indeed, in steers, intramesenteric infusion of butyrate (25 mmol/h) over 3 d increased the net hepatic uptake of L-lactate and alanine by 56.7 and 44.4%, respectively (Reynolds et al, 1992). Decreases in the fractional extraction of propionate were also observed with butyrate in ovine, goat, and bovine hepatocytes by Faulkner and Pollock (1986) and Aiello et al (1989), and in vivo by Krehbiel et al (1992) and Reynolds et al (1992). In the present study, the net hepatic flux of L-lactate switched from a net release to a net uptake, the net hepatic uptake of alanine increased (Our unpublished observations), the hepatic fractional extraction of propionate de-creased while net glucose release remained unchanged.…”

Section: Barley Supplementation and Hepatic Metabolism Of Energy-yielmentioning

confidence: 94%

“…Generally, increased butyrate supply modified the contribution of the different glucose precursors without clearly altering net hepatic glucose release. More specifically, butyrate may stimulate the activity of hepatic pyruvate carboxylase and therefore the synthesis of glucose from precursors such as pyruvate, L-lactate, or alanine at the expense of propionate (Faulkner and Pollock, 1986;Reynolds et al, 1992). Indeed, in steers, intramesenteric infusion of butyrate (25 mmol/h) over 3 d increased the net hepatic uptake of L-lactate and alanine by 56.7 and 44.4%, respectively (Reynolds et al, 1992).…”

Section: Barley Supplementation and Hepatic Metabolism Of Energy-yielmentioning

confidence: 99%

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Ryegrass-based diet and barley supplementation: Partition of energy-yielding nutrients among splanchnic tissues and hind limbs in finishing lambs1

Majdoub

Vermorel

Ortigues-Marty

2003

Journal of Animal Science

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Splanchnic metabolism of energy-yielding nutrients and their uptake by the hind limb were studied in finishing lambs receiving ryegrass harvested at grazing stage (ear at 10 cm) with or without barley supplementation. Six ruminally cannulated and multicatherized lambs (40.2 +/- 1.5 kg) were fed with frozen ryegrass (RG) at 690 kJ of metabolizable energy intake (MEI) x d(-1) x BW(-0.75) successively with and without barley supplementation (RG + B), according to a triplicated Latin square design. Barley supplementation represented 21% of DM intake and increased the MEI by 32% (P < 0.002). In ruminal fluid, barley supplementation increased the acetate and butyrate concentrations by 21.2 and 49.6%, respectively (P < 0.04), without modifying those of propionate. Thus, molar proportions of acetate and butyrate were not modified, and those of propionate tended (P < 0.06) to decrease from 26 to 23%. As a result, the net portal appearance of propionate was not modified. Net portal appearance of butyrate and beta-hydroxybutyrate increased (P < 0.03), and that of acetate was not modified. Consequently, hepatic uptake of butyrate increased and probably spared acetate from hepatic metabolism. The hepatic fractional extraction of propionate decreased (P < 0.03), whereas the net flux of lactate switched from a net release to a net uptake, suggesting an alteration in the contribution of gluconeogenic substrates to glucose synthesis without modification in net hepatic glucose release. As a consequence, barley supplementation increased net splanchnic release of acetate (P < 0.02), propionate (P < 0.001), and beta-hydroxybutyrate (P < 0.01) by 60, 157, and 78%, respectively. In addition, the net splanchnic release of insulin increased (P < 0.03) because of a decrease (P < 0.02) in its hepatic extraction. Despite those changes, the net uptake of nutrients by the hind limb was not modified and even decreased in the case of glucose (P < 0.02), suggesting a stimulation of lipogenesis in adipose tissues. Results from the present study suggested that supplementation of a ryegrass-based diet would likely have little effect on the orientation of muscle energy metabolism and on meat quality because the net uptake of nutrients by the hind limb was unchanged.

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Section: Barley Supplementation and Hepatic Metabolism Of Energy-yielmentioning

confidence: 94%

Section: Barley Supplementation and Hepatic Metabolism Of Energy-yielmentioning

confidence: 99%

Ryegrass-based diet and barley supplementation: Partition of energy-yielding nutrients among splanchnic tissues and hind limbs in finishing lambs1

Majdoub

Vermorel

Ortigues-Marty

2003

Journal of Animal Science

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“…Conversely, liver slices from LN-and LE-fed lambs presented an increased oxidation of [1-14 C]propionate compared with the control animals. An increased activity of the citric acid cycle (and CO 2 production), possibly connected to an increased oxidation of propionyl-CoA or its by-products (Faulkner and Pollock, 1986), can be hypothesized for both the LN and LE diets. A large supply of energy may be necessary 1) to increase protein synthesis ex vivo in the LN slices, 2) to compensate for the marked shortage of energy nutrients in the liver of LE-fed lambs.…”

Section: Gluconeogenesis and Oxidation Of Propionate And Alaninementioning

confidence: 99%

Nitrogen- and energy-imbalanced diets affect hepatic protein synthesis and gluconeogenesis differently in growing lambs1,2

Kraft

Gruffat

Dardevet

et al. 2009

Journal of Animal Science

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The aim of this study was to assess the metabolic fate of AA (endogenous or export protein synthesis, gluconeogenesis, or oxidation) after an imbalanced supply of energy and N in the diet of growing lambs. Eighteen INRA 401 lambs (3 mo old, 29.7 +/- 0.45 kg of BW) were fed 3 experimental diets, one providing a N and energy supply according to recommended allowances (control), one with 23% less N supply relative to energy (LN), and one with 19% less ME supply relative to N (LE). Animals were assigned to 6 blocks of 3, with each animal receiving 1 of the 3 diets, and the animals from each block were slaughtered on the same day. Liver slices from these lambs were incubated in a minimum salt medium (Krebs-Henseleit) containing physiological concentrations of propionate and AA as energy and N sources, similarly across all 3 treatments. Protein synthesis (endogenous and export) using [U-(14)C]valine and [(35)S]methionine, gluconeogenesis from [1-(14)C]propionate and [U-(14)C]alanine, and oxidation were measured. A relative sparing of AA at the liver level was observed with the LN diet because of reduced urinary N (-42%, LN vs. control, P < 0.001). The AA were also directed toward anabolic purposes in the LN diet via an increased endogenous and total export protein synthesis (+51%, LN vs. control, P = 0.01; also observed for fibrinogen synthesis, but not for albumin or transferrin) associated with a tendency for increased gluconeogenesis from alanine (+58%, LN vs. LE, P = 0.08). On the other hand, the LE diet resulted in a marked loss of N in urine (+24%, LE vs. control, P < 0.05), but no notable effect of the LE diet was demonstrated for protein synthesis or gluconeogenesis ex vivo. These data demonstrate a more efficient utilization of AA for anabolic purposes in the lambs fed LN, probably via an activation of some AA transport systems, to address the shortage of nitrogenous nutrients in the LN diet. By contrast, no such adaptation occurred in the LE lambs, probably because the regulatory mechanisms that prevailed in this case were the nutrient supply or hormones, which were not altered in our ex vivo experimental model.

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“…This evidence suggests that the control of the distribution of propionate carbon between oxidation and gluconeogenic pathways normally favours gluconeogenesis and could only assume physiological significance if the animals are fed on diets which give rise to very high propionate concentrations in the portal vein (Elliot, 1980). Note added in proof (received 22 September 1986) Faulkner & Pollock (1986) have reported the inhibitory effects of fatty acids on production of lactate and pyruvate by sheep hepatocytes incubated with propionate.…”

Section: Resultsmentioning

confidence: 99%

The effect of fatty acids and starvation on the metabolism of gluconeogenic precursors by isolated sheep liver cells

Lomax¹,

Donaldson²,

Pogson³

1986

Biochemical Journal

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Isolated liver cells prepared from fed sheep synthesize glucose from propionate at twice the rate observed with cells from starved animals. Addition of palmitate or palmitate + carnitine to incubations of liver cells from starved animals inhibited the rate of glucose synthesis with lactate as a precursor, but had little effect when propionate and pyruvate were substrates. Liver cells from fed and starved sheep synthesized lactate and pyruvate when incubated with propionate. Fatty acids inhibited this formation of lactate and pyruvate from propionate. It is proposed that the different responses of gluconeogenic precursors to fatty acids can be explained by the effect of reducing equivalents on the transport of carbon atoms across the mitochondrial membrane.

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Propionate metabolism and its regulation by fatty acids in ovine hepatocytes

Cited by 15 publications

References 11 publications

Ryegrass-based diet and barley supplementation: Partition of energy-yielding nutrients among splanchnic tissues and hind limbs in finishing lambs1

Ryegrass-based diet and barley supplementation: Partition of energy-yielding nutrients among splanchnic tissues and hind limbs in finishing lambs1

Nitrogen- and energy-imbalanced diets affect hepatic protein synthesis and gluconeogenesis differently in growing lambs1,2

The effect of fatty acids and starvation on the metabolism of gluconeogenic precursors by isolated sheep liver cells

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