Measurement of calcium and phosphorus fluxes during lactation in the rat
Novel, two-compartment metabolic cages for rats were constructed to examine Ca and P fluxes during lactation. Four consecutive balance studies of 4 d each were performed in lactating rats and nonlactating controls. Lactating rats had dramatically higher intestinal absorptions of Ca and P resulting from both increased food consumption and elevated fractional absorptions of these elements. Urinary Ca excretion was reduced during lactation whereas urinary P excretion was unchanged. Endogenous fecal Ca excretion (determined by infusing /sup 45/Ca and dividing fecal /sup 45/Ca content by urinary /sup 45/Ca specific activity) was similar in lactating and nonlactating rats. In a separate study, pup retention of ingested Ca averaged 96%. Therefore, the difference in pup carcass Ca content between d 1 and 17 of age is assumed to equal 96% of the Ca transfer rate into milk. Similar calculations were applied to P. Milk transfer rates were determined to be 126 and 99 mg/d for Ca and P, respectively. These calculations indicate that 19% of the Ca transferred to milk was derived from the maternal skeleton with the maternal diet supplying the remaining Ca. This study provides the first comprehensive analysis of the alterations in Ca and P fluxes that occur during lactation in the rat.
- Research Organization:
- Michael Reese Hospital and Medical Center, Chicago, IL (USA)
- OSTI ID:
- 6075621
- Journal Information:
- J. Nutr.; (United States), Vol. 119:3
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CALCIUM
METABOLISM
PHOSPHORUS
BODY BURDEN
CALCIUM 45
DIET
FECES
INTESTINAL ABSORPTION
LACTATION
MILK
PREGNANCY
RATS
TRACER TECHNIQUES
ABSORPTION
ALKALINE EARTH ISOTOPES
ALKALINE EARTH METALS
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOLOGICAL MATERIALS
BIOLOGICAL WASTES
BODY FLUIDS
CALCIUM ISOTOPES
DAYS LIVING RADIOISOTOPES
ELEMENTS
EVEN-ODD NUCLEI
FOOD
INTERMEDIATE MASS NUCLEI
ISOTOPE APPLICATIONS
ISOTOPES
MAMMALS
MATERIALS
METALS
NONMETALS
NUCLEI
RADIOISOTOPES
RODENTS
UPTAKE
VERTEBRATES
WASTES
550501* - Metabolism- Tracer Techniques