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Lack of correlation between milk glucose concentrations and rates of milk production in the rat

Published online by Cambridge University Press:  01 June 2009

Murray R. Grigor
Affiliation:
Department of Biochemistry, University of Otago, Dunedin, New Zealand
Janet M. Carrington
Affiliation:
Department of Biochemistry, University of Otago, Dunedin, New Zealand
Peter G. Arthur
Affiliation:
Department of Biochemistry, University of Western Australia, Nedlands, WA 6009, Australia
Peter E. Hartmann
Affiliation:
Department of Biochemistry, University of Western Australia, Nedlands, WA 6009, Australia

Summary

Concentrations of lactose, α-lactalbumin (α-la), glucose and glucose-6-phosphate were measured in milk obtained from rats under conditions where the rates of milk production varied from 0 to 2·6 g/h. In the milk from rats fed a low protein diet where milk production was 0·9 g/h, the concentration of α-la was 1·5 mg/ml, being significantly lower than that in the milk of control rats at 2·9 mg/ml and where the rate of milk production was 2·6 g/h. No differences were detected in the glucose concentrations. When rats were fed restricted amounts of the control diet and where milk production varied from 0 to 1·7 g/h during the course of the day, no differences in the concentrations of either α-la or glucose were detected. These results suggest that considerable caution must be used in interpreting the significance of milk glucose in the rat.

Type
Original Articles
Copyright
Copyright © Proprietors of Journal of Dairy Research 1989

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References

REFERENCES

Bligh, E. G. & Dyer, W. J. 1959 A rapid method of total lipid extraction and purification. Canadian Journal of Biochemistry and Physiology 37 911917CrossRefGoogle ScholarPubMed
Carrick, D. T. & Kuhn, N. J. 1978 Diurnal variation and response to food withdrawal of lactose synthesis in lactating rats. Biochemical Journal 174 319325CrossRefGoogle ScholarPubMed
Chaiyabutr, N., Faulkner, A. & Peaker, M. 1981 Changes in the concentrations of the minor constituents of goat's milk during starvation and on refeeding of the lactating animal and their relationship to mammary gland metabolism. British Journal of Nutrition 45 149157CrossRefGoogle ScholarPubMed
Faulkner, A. 1985 Glucose availability and lactose synthesis in the goat. Biochemical Society Transactions 13 496497CrossRefGoogle Scholar
Faulkner, A., Blatchford, D. R., White, J. M. & Peaker, M. 1982 Changes in the concentrations of metabolites in milk at the onset and cessation of lactation in the goat. Journal of Dairy Research 49 399405CrossRefGoogle ScholarPubMed
Faulkner, A., Chaiyabutr, N., Peaker, M., Carrick, D. T. & Kuhn, N. J. 1981 Metabolic significance of milk glucose. Journal of Dairy Research 48 5156CrossRefGoogle ScholarPubMed
Faulkner, A., Henderson, A. J. & Blatchford, D. R. 1985 The transport of metabolites into goat's milk. Biochemical Society Transactions 13 495496CrossRefGoogle Scholar
Fitzgerald, D. K., Brodbeck, U., Kiyosawa, I., Mawal, R., Colvin, B. & Ebner, K. E. 1970 α-Lactalbumin and the lactose synthetase reaction. Journal of Biological Chemistry 245 21032108CrossRefGoogle ScholarPubMed
Geursen, A. & Grigor, M. R. 1987 Serum albumin secretion in rat milk. Journal of Physiology 391 419427CrossRefGoogle ScholarPubMed
Grigor, M. R., Allan, J., Carne, A., Carrington, J. M. & Geursen, A. 1986 a Milk composition of rats feeding restricted litters. Biochemical Journal 233 917919CrossRefGoogle ScholarPubMed
Grigor, M. R., Allan, J. E., Carrington, J. M., Carne, A., Geursen, A., Young, D., Thompson, M. P., Haynes, E. B. & Coleman, R. A. 1987 Effect of dietary protein and food restriction on milk production and composition, maternal tissues and enzymes in lactating rats. Journal of Nutrition 117 12471258CrossRefGoogle ScholarPubMed
Grigor, M. R., Poczwa, Z. & Arthur, P. G. 1986 b Milk lipid synthesis and secretion during milk stasis in the rat. Journal of Nutrition 116 17891797CrossRefGoogle ScholarPubMed
Grigor, M. R. & Thompson, M. P. 1987 Diurnal regulation of milk lipid production and milk secretion in the rat: effect of dietary protein and energy restriction. Journal of Nutrition 117 748753CrossRefGoogle ScholarPubMed
Holt, C. 1983 Swelling of Golgi vesicles in mammary secretory cells and its relation to the yield and quantitative composition of milk. Journal of Theoretical Biology 101 247261CrossRefGoogle Scholar
Jenness, R. 1974 The composition of milk. In Lactation: a comprehensive treatise Vol. 3, pp. 3107 (Eds Larson, B. L. and Smith, V. R.). New York: Academic PressGoogle Scholar
Kuhn, N. J. & Lowenstein, J. M. 1967 Lactogenesis in the rat: changes in metabolic parameters at parturition. Biochemical Journal 105 9951002CrossRefGoogle ScholarPubMed
Kuhn, N. J. & White, A. 1975 a The topography of lactose synthesis. Biochemical Journal 148 7784CrossRefGoogle ScholarPubMed
Kuhn, N. J. & White, A. 1975 b Milk glucose as an index of the intracellular glucose concentration of rat mammary gland. Biochemical Journal 152 153155CrossRefGoogle ScholarPubMed
Kunst, A., Draeger, B. & Ziegenhorn, J. 1984 UV-methods with hexokinase and glucose-6-phosphate dehydrogenase. In Methods of Enzymatic Analysis, 3rd edn, Vol 6, pp. 163172 (Ed. Bergmeyer, H. U.). Weinheim: Verlag-ChemieGoogle Scholar
Linzell, J. L. & Peaker, M. 1971 Mechanism of milk secretion. Physiological Reviews 51 564597CrossRefGoogle ScholarPubMed
Lowry, O. H., Rosebrough, N. J., Farr, A. L. & Randall, R. J. 1951 Protein measurement with the Folin phenol reagent. Journal of Biological Chemistry 193 265275CrossRefGoogle ScholarPubMed
Mansaray, Y. K. C. & Grimble, R. 1984 Lactose production, milk volume and lactose synthetase (EC 2.4.1.22) activity in rats fed on diets of varying protein adequacy. Proceedings of the Nutrition Society 43 49 AGoogle Scholar
Murphy, G., Ariyanayagam, A. D., &Kuhn, N. J. 1973 Progesterone and the metabolic control of the lactose biosynthetic pathway during lactogenesis in the rat. Biochemical Journal 136 11051116CrossRefGoogle ScholarPubMed
Navaratnam, N., Virk, S. S., Ward, S. & Kuhn, N. J. 1986 Cationic activation of galactosyltransferase from rat mammary Golgi membranes by polyamines and by basic peptides and proteins. Biochemical Journal 239 423433CrossRefGoogle ScholarPubMed
Navaratnam, N., Ward, S., Fisher, G., Kuhn, N. J., Keen, J. N. & Findlay, J. B. C. 1988 Purification, properties and cation activation of galactosyltransferase from lactating-rat mammary Golgi membranes. European Journal of Biochemistry 171 623629CrossRefGoogle ScholarPubMed
Wilde, C. H. & Kuhn, N. J. 1979 Lactose synthesis in the rat, and the effects of litter size and malnutrition. Biochemical Journal 182 287294CrossRefGoogle ScholarPubMed
Zar, J. H. 1974 Biostatistical Analysis pp. 151162. Englewood Cliffs, NJ: Prentice-HallGoogle Scholar