Physiology and Biochemistry of Lactation

Mepham, T. B.; Kuhn, Nicholas J.

doi:10.1007/978-94-011-1286-4_12

Cited by 39 publications

(69 citation statements)

References 380 publications

(367 reference statements)

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“…1.22). Approximately 70% of the net glucose uptake from blood by lactating bovine mammary glands is used for lactose synthesis and the remainder is oxidized in pentose and TCA cycles (14). The lactose is synthesized in the Golgi apparatus from one free glucose and one uridine diphosphate galactose arising from glucose-6-phosphate.…”

Section: Discussionmentioning

confidence: 99%

“…As a major osmolyte in milk, lactose concentration changes little and lactose synthesis rate is the main determinant of overall milk yield (13). Glucose is also metabolized in mammary tissue to facilitate synthesis of other milk components such as fatty acids (14). Thus the control of glucose transport and metabolism by mammary glands is important to milk synthesis and the glucose economy of the lactating animal.…”

mentioning

confidence: 99%

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Kinetics of glucose transport and sequestration in lactating bovine mammary glands measured in vivo with a paired indicator/nutrient dilution technique

Qiao¹,

Trout²,

Xiao³

et al. 2005

Journal of Applied Physiology

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Qiao, Fulong, Donald R. Trout, Changting Xiao, and John P. Cant. Kinetics of glucose transport and sequestration in lactating bovine mammary glands measured in vivo with a paired indicator/ nutrient dilution technique. J Appl Physiol 99: 799 -806, 2005. First published May 19, 2005; doi:10.1152/japplphysiol.00386.2004.-To quantify kinetics of mammary glucose utilization in vivo, 24 paired glucose and extracellular indicator (p-aminohippuric acid) dilution curves across intact bovine mammary glands were obtained after bolus injections into the external iliac artery. Dilution curves were analyzed using a compartmental capillary, convolution integration model. Four candidate submodels of glucose transport and metabolism in capillary supply zones were fit to the glucose dilution curves and evaluated. Model I, with one extracellular compartment for glucose and first-order unidirectional uptake, failed, indicating that efflux of glucose from the intracellular space could not be ignored. Model II, with first-order exchanges between extracellular and intracellular compartments and sequestration from the latter, was overdefined because unidirectional clearance of glucose was at least five times the blood flow rate and 20 times the net clearance rate. Model III, combining extracellular and intracellular space into one compartment, was superior in its goodness-of-fit to curves and identifiability of parameters. Michaelis-Menten parameters of sequestration were not identifiable. Parameters of the optimal compartmental capillary, convolution integration model were applicable to both the dynamics of injected glucose dilution and the steady-state background arteriovenous difference of glucose. Glucose sequestration followed firstorder kinetics between 0 and 7 mM extracellular glucose with an average rate constant of 0.006 s Ϫ1 or a clearance of 44 ml/s. The ratio of intracellular to extracellular glucose distribution space was 0.34, which is considerably lower than the expected intracellular volume and suggests an intracellular occlusion compartment with which extracellular glucose rapidly exchanges. lactose synthesis; glucose uptake; arteriovenous differences NET UPTAKE OF GLUCOSE by the mammary glands of a lactating cow consumes 60 to 70% of the whole body glucose turnover and up to 90% of that uptake is used for lactose synthesis (1, 18). As a major osmolyte in milk, lactose concentration changes little and lactose synthesis rate is the main determinant of overall milk yield (13). Glucose is also metabolized in mammary tissue to facilitate synthesis of other milk components such as fatty acids (14). Thus the control of glucose transport and metabolism by mammary glands is important to milk synthesis and the glucose economy of the lactating animal.Infusion of glucose for 10 h into the arterial supply of bovine mammary glands to increase blood plasma concentration from 3.6 to 6.4 mM caused only an 18% increase in milk lactose secretion rate (5). Similarly, lactose synthesis rate was unrelated to circulating glucose concentrat...

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Kinetics of glucose transport and sequestration in lactating bovine mammary glands measured in vivo with a paired indicator/nutrient dilution technique

Qiao¹,

Trout²,

Xiao³

et al. 2005

Journal of Applied Physiology

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“…After correcting for loss of activity this would amount to only 0.001 % of total milk protein. In all mammalian species the level of milk secretion is close to 1.67 ml\g of tissue in a 24 h period [33]. This would mean secretion of 0.6 µg of GCK over this time (a relatively low level of protein).…”

Section: Discussionmentioning

confidence: 99%

Purification of Golgi casein kinase from bovine milk

Duncan

Wilkinson

Burgoyne

2000

Biochemical Journal

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Caseins and many other secretory proteins are phosphorylated during their transport through the secretory pathway by a protein kinase present within Golgi compartments. Molecular analysis of the Golgi casein kinase (GCK) has not been possible since it has not been purified to homogeneity or been cloned. Previous attempts have been made to purify GCK activity from mammary gland Golgi fractions, but these have not resulted in extensive purification of the enzyme. In the present study, we have demonstrated that substantial amounts of GCK activity, assayed using a specific peptide substrate, can be detected as a soluble form in bovine milk, and we have used milk as a source for purification. A purification protocol was established that allowed > 80000-fold purification to a specific activity of GCK (approx. 700nmoles/min per mg of protein) far higher than previously achieved. These findings cast doubts on previous claims for purification of GCK activity. In addition, ion-exchange chromotography resolved two closely eluting peaks of activity, suggesting the existence of two related, but distinct, GCK activities.

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“…The appearance of epithelial cells is cuboidal while the myoepithelial cells are flattened in shape (Mepham, 1983). The histological observations, from photomicrographs of the slides of each group shown as in Fig.…”

Section: Biochemical and Histological Studiesmentioning

confidence: 96%

“…The yield of milk in any animal is the product of the output per active secretory cell and to the total number of such cells (Mepham, 1983). The parenchyma percentage represents the relative amount of the cells concerned with the lactation to the stroma.…”

Section: Biochemical and Histological Studiesmentioning

confidence: 99%

Assessment of lactogenic potential of some traditional herbs

Raval¹,

Patel²,

Mishra³

2010

Oriental Pharmacy and Experimental Medicine

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SUMMARYThe entire plant of Leptadenia reticulata (Asclepidaceae) is extensively used as lactogen, traditionally, in veterinary practice. The plants of Dregea volubilis and Pentatropis microphylla (Asclepidaceae) are now used as its substitute and sometimes replace the original drug as traditional lactogen. The lactogenic potential of these drugs was studied in rats using, pup weight, weight of mother, parenchyma percentage, secretary rating, estimation of total protein content and glycogen content of mammary glands tissues as assessment parameters. HPTLC profiles of bioactive extracts were also generated to serve the authentification needs. The results of present studies show that P.microphylla forms a better substitute over D. volubilis.

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Physiology and Biochemistry of Lactation

Cited by 39 publications

References 380 publications

Kinetics of glucose transport and sequestration in lactating bovine mammary glands measured in vivo with a paired indicator/nutrient dilution technique

Kinetics of glucose transport and sequestration in lactating bovine mammary glands measured in vivo with a paired indicator/nutrient dilution technique

Purification of Golgi casein kinase from bovine milk

Assessment of lactogenic potential of some traditional herbs

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