Measurement of calcium and phosphorus fluxes during lactation in the rat

Journal Article · Wed Mar 01 04:00:00 EST 1989 · J. Nutr.; (United States)

OSTI ID:6075621

Brommage, R

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), Journal Name: J. Nutr.; (United States) Vol. 119:3; ISSN JONUA
• Country of Publication: United States
• Language: English

Related Subjects

550501* -- Metabolism-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ABSORPTION
ALKALINE EARTH ISOTOPES
ALKALINE EARTH METALS
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOLOGICAL MATERIALS
BIOLOGICAL WASTES
BODY BURDEN
BODY FLUIDS
CALCIUM
CALCIUM 45
CALCIUM ISOTOPES
DAYS LIVING RADIOISOTOPES
DIET
ELEMENTS
EVEN-ODD NUCLEI
FECES
FOOD
INTERMEDIATE MASS NUCLEI
INTESTINAL ABSORPTION
ISOTOPE APPLICATIONS
ISOTOPES
LACTATION
MAMMALS
MATERIALS
METABOLISM
METALS
MILK
NONMETALS
NUCLEI
PHOSPHORUS
PREGNANCY
RADIOISOTOPES
RATS
RODENTS
TRACER TECHNIQUES
UPTAKE
VERTEBRATES
WASTES