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The effect of dietary P level and the Ca:available P on Na‐dependent phosphate transport in the small intestine of weanling pigs
Author(s) -
Saddoris Kari,
Walsh Maria,
Radcliffe John Scott
Publication year - 2006
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.20.5.a1053-a
Subject(s) - weanling , jejunum , phosphate , small intestine , chemistry , medicine , endocrinology , zoology , biochemistry , biology
Feeding a low P diet to rodents, has been shown to increase Na‐dependent phosphate transport in the small intestine. However, results reported in the literature are confounded by the feeding of wide Ca:available P (aP) in excess of 20:1. The objectives of this study were to determine the effects of a low P diet and the Ca:aP on Na‐dependent nutrient transport. Intestines (jejunum) from weanling piglets fed an adequate or a low P diet with adequate or low Ca (Ca:aP ranged from 1.4 to 4.3) were mounted in modified Ussing chambers. Initial basal short circuit current, resistance, and potential difference did not differ (P>0.10) between treatment groups. As expected, Na‐dependent phosphate transport was increased (P=0.015) from 7.00 to 13.04 μA/cm 2 in the jejunum as dietary aP level was decreased. Na‐dependent glucose uptake increased (P=0.067) from 11.39 to 17.9 μA/cm 2 as dietary P level was decreased. However, no dietary Ca effects or P × Ca interactions were detected (P>0.10) for Na‐dependent phosphate or glucose transport in the intestine. This data indicates that the level of aP in the diet is the main factor effecting Na‐dependent phosphate uptake in the small intestine. Varying the Ca:aP in low P diets from 2.5 to 4.3, by adjusting Ca levels, had no effect on Na‐dependent phosphate transport. Based on the results of this experiment, negative effects often observed when a wide Ca:aP is fed on P utilization are not due to alterations in Na‐dependent phosphate uptake. Surprisingly, Na‐dependent glucose uptake was increased 36% by feeding pigs a low P diet and was also independent of both Ca level and Ca:aP in the diet.