Mode of formation of milk fatty acids from acetate in the goat

Popják, G.; French, Todd; Hunter, G. D.; Martin, A. J. P.

doi:10.1042/bj0480612

Cited by 186 publications

(30 citation statements)

References 9 publications

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“…There were significant changes in the fatty acid composition of milk fat during starvation. The content of acids of chainlength C4-C14 which are synthesized de novo in the gland in fed animals (Popjak, French, Hunter & Martin, 1951; Annison, Linzell, Fazakerley & Nichols, 1967) fell steadily over the whole period (Fig. 2).…”

Section: Mammary Metabolism and Secretionmentioning

confidence: 99%

Mammary and whole animal metabolism of glucose and fatty acids in fasting lactating goats

Annison¹,

Linzell²,

West³

1968

The Journal of Physiology

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SUMMARY1. Measurements were made of milk yield, mammary blood flow and mammary arteriovenous differences during the measurement of substrate entry rate by the isotope dilution method using [U-14C] acids at 094-6-8 mg/min/kg and 6-9 % of total CO2 was derived from each. The udder took up 3-0-5*7 mg/min/kg of tissue and 4-8 % of mammary CO2 was derived from each acid. In the udder 8 and 5-5 % of stearate and oleate were oxidized and 25 % of palmitate. Mammary uptake of stearate was 31-5 % of the total entry rate, palmitate 1 %, and oleate 7-5 %. Only long chain milk fatty acids were labelled. 6. During fasting the mammary R.Q. was 0-85 + 0 045 compared with a value in fed animals of 1-24 + 0-02, when the udder is synthesizing fatty acids from acetate. The total mammary uptake of lipid precursors was only 74 % of the rate of milk fat secretion and there was an 18 % shrinkage in empty udder volume, suggesting the use of endogenous mammary tissue substrates.

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Section: Mammary Metabolism and Secretionmentioning

confidence: 99%

Mammary and whole animal metabolism of glucose and fatty acids in fasting lactating goats

Annison¹,

Linzell²,

West³

1968

The Journal of Physiology

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“…On a similar basis, taking 24.2 pmol x g-' x h-' as a Table 4) and allowing for the part incorporated directly into glycerol (calculated from the [3,4-'4C]glucose data of Table 3), the total amount of lipid that would be formed by a weight of cells equivalent to the whole gland would be 0.77 g and this figure becomes 1.46 g in the presence of insulin. To these figures has to be added the direct uptake of lipid from the blood which is incorporated into the milk fat without metabolic modification and which accounts for approximately 50y0 of the milk fat [21]. Thus, the above figures become approximately 1.5 g and 3.0 g in the absence and presence of insulin respectively.…”

Section: Lclciuting Nzanitnury Glundmentioning

confidence: 99%

Regulation of Mammary Gland Metabolism

Greenbaum

Salam

Sochor

et al. 1978

European Journal of Biochemistry

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1.A method for the preparation of isolated mammary gland cells of the rat is described. 2. The procedure involves disaggregation of the tissue in a collagenase-hyaluronidase mixture and subsequent purification of the heterogeneous population of cells by centrifugation in discontinuous Ficoll-400 gradients ; the preparation takes 60 minutes. The yield of cells is approximately 147.6.3. The cells as prepared have high rates of metabolism and synthetic capacity and exhibit metabolic characteristics comparable to intact tissue.4. Measurements of the content of metabolic intermediates show cells to have, and retain, 'outstandingly high levels of ATP and to have an energy charge close to 0.9. Levels of other intermediates approximate to those found in the intact tissue. The level of glycolytic inkrmediates below the triose phosphate stage indicate the highly aerobic state of the cells.5. The pattern and scale of glucose utilization, measured using specifically labelled glucose incorporation into I4CO2 and 14C-labelled lipid production, approximates closely in isolated cells at 5 and 20 mM glucose and in tissue slices at 20 mM glucose concentration. Mammary gland slices incubated with 5 mM glucose have a considerably lower rate of metabolism. Isolated cells exhibit a higher proportionate rate of glucose utilization by way of the pentose phosphate pathway.6. The isolated cells are hormone responsive. Insulin increases the oxidation of glucose by the pentose phosphate pathway and stimulates lipid synthesis. Addition of progesterone and cortisone in vitro (10 pM) leads to a marked and rapid decrease in the rate of glucose oxidation and conversion to lipid.The metabolic activity of rat mammary tissue varies sharply over the lactation cycle. Two transitions, that from the relatively quiescent pregnant gland to the actively secreting gland which occurs at parturition and the second from the fully active lactating gland at the end of lactation to the inactive state which results from the cessation of suckling, are controlled by shifts in the hormonal balance of the animal (see Folley [l]) and by changes in the intracellular concentrations of a few metabolites [2]. Similar factors control the progressive rise in the rate of milk formation which occurs over the whole of the lactation period in response to the increasing needs of the growing pups.

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“…This is so in the intact body and liver of the rat (Bloch 1947), in the mammary gland of ruminants (Folley and French 1950;Popjak et al 1951), in the liver, intestinal wall, and lung of the rabbit and lung of the ruminant (Popjak and Beeckmans 1950), and in adipose tissue of the rat (Hangaard and Marsh 1952); but it is not detectably utilized for this purpose by at least heart and diaphragm muscle (Pearson, Hast-. ings, and Bunting 1949; or kidney of the rat (Pardie, Heidelberger, and Potter 1950;Elliott and Kalnitsky 1950), the kidney experiments showing that practically all acetate metabolized was oxidized.…”

Section: Theory Relating To the Specific Dynamic Acrion Of Aceticmentioning

confidence: 99%

“…(b) Acetic acid is oxidized by many, possibly all, individual tissues, including heart muscle (Lorber et al 1946;Pearson, Hastings, and Bunting 1949;, diaphragm muscle , gastrocnemus muscle (Lifson, Omachi, and Cavert 1951), lung, liver, and kidney (Pardie, Heidelberger, and Potter 1950), and mammary gland (Folley and French 1950;Popjak et al 1951). Brain has been reported not to utilize acetic acid in vitro (Long and Peters 1939) but it is possible that the finding may be due to initial exhaustion of the tricarboxylic acid cycle by which acetic acid is oxidized.…”

Section: Theory Relating To the Specific Dynamic Acrion Of Aceticmentioning

confidence: 99%

Specific Dynamic Action of Acetic Acid and Heat Increment of Feeding in Ruminants

McClymont¹

1952

Aust. Jnl. Of Bio. Sci.

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SummaryAttention is drawn to the lack of adequate explanation of the phenomena of the high specific dynamic action of acetic acid and the high heat increment of feeding in ruminants.The theory is advanced that the high specific dynamic action of acetic acid is related to the following facts: it is non-glyconeogenic; it is not utilized in protein synthesis; it is oxidized by most, if not all, tissues; and it is utilized significantly for lipogenesis by only a few tissues, excluding in particular muscle and kidney. Furthermore, the metabolism of the acid appears to be relatively "uncontrolled," the uptake by tissues being directly dependent on the arterial level and unaffected by insulin, at least in ruminants, in contrast to glucose.Finally, there is very little storage of absorbed acetic acid in the body Huids. Consequently, it is metabolized almost as fast as it is absorbed: in some tissues, notably intestinal wall, liver, and adipose tissue and lung, it is partitioned .between oxidation and lipogenesis; in others, particularly muscle and kidney, it is of necessity largely utilized oxidatively. The high specific dynamic action of acetic acid indicates that the net partition is in favour of oxidation.The high heat increment of feeding in ruminants is considered as due to the quantitative importance of acetic acid and butyric acid, which also has a high specific dynamic action, as products of ruminal digestion, and of acetic acid and fl-hydroxybutyric acid, derived from acetic and butyric acids, as peripheral metabolites.

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Mode of formation of milk fatty acids from acetate in the goat

Cited by 186 publications

References 9 publications

Mammary and whole animal metabolism of glucose and fatty acids in fasting lactating goats

Mammary and whole animal metabolism of glucose and fatty acids in fasting lactating goats

Regulation of Mammary Gland Metabolism

Specific Dynamic Action of Acetic Acid and Heat Increment of Feeding in Ruminants

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