Premium
A Rodent Model to Evaluate the Effect of Dietary Protein on Intestinal Calcium Absorption
Author(s) -
GaffneyStomberg Erin,
Cucchi Carrie E.,
Sun Benhua,
Simpson Christine A.,
Kerstetter Jane E.,
Insogna Karl L.
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.726.1
Subject(s) - endocrinology , osteocalcin , medicine , calcium , chemistry , brush border , calcium metabolism , bone remodeling , absorption (acoustics) , transcellular , urine , vitamin d and neurology , alkaline phosphatase , biology , vesicle , biochemistry , physics , membrane , acoustics , enzyme
In humans, increasing dietary protein increases intestinal Ca absorption. To further study this effect, rats were randomly assigned to consume a control (20%), low (5%) or high (40%) protein diet for 7 days. All diets were isocaloric and contained 0.45% Ca, 0.35% P. Twenty‐four hr urines, blood and feces were collected to assess Ca metabolism, Ca balance and bone turnover. Brush border membrane vesicles (BBMV) were prepared from duodenal mucosa to measure Ca transport. Urine Ca rose during the high protein diet and fell during the low diet (p<0.01). There were no changes in serum Ca or vitamin D metabolites on any diet. Serum PTH trended higher in the low protein group (p=0.07) and serum osteocalcin was significantly higher compared to the other groups (p<0.03). Rats consuming the high protein diet absorbed and retained more Ca compared to the low protein group (48.5% vs. 34.1% and 45.8% vs. 33.7% respectively, p<0.01). Ca transport was significantly higher in the BBMV from animals consuming the high protein diet (p<0.001). This animal model recapitulates the findings in humans in that changes in Ca absorption explain the changes in UCa. The higher osteocalcin and PTH during the low protein diet suggest that bone turnover was increased during low protein intake. The BBMV studies indicate that increased transcellular Ca uptake contributes to the increase in Ca absorption during the high protein diet.