Abstract
1. Changes in milk composition and in mammary permeability to labelled sucrose and monovalent ions have been studied in late pregnancy and at the time of parturition. These data have been compared with those obtained previously in lactating goats.
2. Colostrum contained more sodium, chloride, protein, immunoglobulins and less potassium and lactose than milk. The composition of the aqueous phase changed near term and normal milk composition was reached either several days before or several days after parturition. The main decrease in the immunoglobulin concentration occurred when the animal was first milked or suckled.
3. In contrast to lactating animals, [14C]sucrose passed from blood to milk and [14C]lactose from milk to blood. There was a significant correlation between the entry of labelled sucrose into milk and the sodium concentration.
4. The rate of passage of 24Na and 36Cl into milk from blood was higher in late pregnancy than in lactation.
5. In late pregnancy, the concentrations of both sodium and chloride were inversely correlated with the concentration of lactose while there was a positive correlation between potassium and lactose.
6. Hydrostatic pressure in the lumen of the mammary gland increased during late pregnancy but there was no significant correlation with the composition of the aqueous phase of milk.
7. When one gland of 4 animals was milked twice-daily starting 9-19 days before parturition, the composition of the secretion changed to that of normal milk only in the gland that was being milked. Similarly, [14C]sucrose, 24Na and 36Cl entry from blood decreased. Milk yield also increased but a further increase occurred post-partum.
8. Comparison of the passage of 3HOH, 24Na and 36Cl into different fractions of milk during I.A. infusions indicates that the mammary ducts are less permeable to ions than the alveoli, but it was not possible to decide whether the ducts are as impermeable as during lactation.
9. It is suggested that ion and lactose movements occur via a para-cellular route and these results are discussed in relation to transport mechanisms and in terms of local and systemic controlling mechanisms.
Full text
PDF






















Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Chatwin A. L., Linzell J. L., Setchell B. P. Cardiovascular changes during lactation in the rat. J Endocrinol. 1969 Jun;44(2):247–254. doi: 10.1677/joe.0.0440247. [DOI] [PubMed] [Google Scholar]
- Claude P., Goodenough D. A. Fracture faces of zonulae occludentes from "tight" and "leaky" epithelia. J Cell Biol. 1973 Aug;58(2):390–400. doi: 10.1083/jcb.58.2.390. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Fleet I. R., Linzell J. L., Peaker M. The use of an autoanalyzer for the rapid analysis of milk constituents affected by subclinical mastitis. Br Vet J. 1972 Jun;128(6):297–300. doi: 10.1016/s0007-1935(17)36934-8. [DOI] [PubMed] [Google Scholar]
- Frömter E., Diamond J. Route of passive ion permeation in epithelia. Nat New Biol. 1972 Jan 5;235(53):9–13. doi: 10.1038/newbio235009a0. [DOI] [PubMed] [Google Scholar]
- LINZELL J. L. Mammary-gland blood flow and oxygen, glucose and volatile fatty acid uptake in the conscious goat. J Physiol. 1960 Oct;153:492–509. doi: 10.1113/jphysiol.1960.sp006550. [DOI] [PMC free article] [PubMed] [Google Scholar]
- LINZELL J. L. Physiology of the mammary glands. Physiol Rev. 1959 Jul;39(3):534–576. doi: 10.1152/physrev.1959.39.3.534. [DOI] [PubMed] [Google Scholar]
- Linzell J. L., Peaker M. Changes in mammary gland permeability at the onset of lactation in the goat: an effect on tight junctions? J Physiol. 1973 Apr;230(1):13P–14P. [PMC free article] [PubMed] [Google Scholar]
- Linzell J. L., Peaker M. Intracellular concentrations of sodium, potassium and chloride in the lactating mammary gland and their relation to the secretory mechanism. J Physiol. 1971 Aug;216(3):683–700. doi: 10.1113/jphysiol.1971.sp009547. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Linzell J. L., Peaker M. Mechanism of milk secretion. Physiol Rev. 1971 Jul;51(3):564–597. doi: 10.1152/physrev.1971.51.3.564. [DOI] [PubMed] [Google Scholar]
- Linzell J. L., Peaker M. The effects of oxytocin and milk removal on milk secretion in the goat. J Physiol. 1971 Aug;216(3):717–734. doi: 10.1113/jphysiol.1971.sp009549. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Linzell J. L., Peaker M. The permeability of mammary ducts. J Physiol. 1971 Aug;216(3):701–716. doi: 10.1113/jphysiol.1971.sp009548. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Pitelka D. R., Hamamoto S. T., Duafala J. G., Nemanic M. K. Cell contacts in the mouse mammary gland. I. Normal gland in postnatal development and the secretory cycle. J Cell Biol. 1973 Mar;56(3):797–818. doi: 10.1083/jcb.56.3.797. [DOI] [PMC free article] [PubMed] [Google Scholar]
- SELDINGER S. I. Catheter replacement of the needle in percutaneous arteriography; a new technique. Acta radiol. 1953 May;39(5):368–376. doi: 10.3109/00016925309136722. [DOI] [PubMed] [Google Scholar]
- Sala N. L., Cannata M. A., Luther E., Arballo J. C., Tramezzani J. H. Inhibition of milk secretion by intraperitoneal injections of milk into lactating mice. J Endocrinol. 1973 Jan;56(1):79–84. doi: 10.1677/joe.0.0560079. [DOI] [PubMed] [Google Scholar]
- UDY D. C. A rapid method for estimating total protein in milk. Nature. 1956 Aug 11;178(4528):314–315. doi: 10.1038/178314a0. [DOI] [PubMed] [Google Scholar]
