TY - JOUR
T1 - Effect of glucocorticoids on neonatal rabbit renal cortical sodium- inorganic phosphate messenger RNA and protein abundance
AU - Prabhu, Satish
AU - Levi, Moshe
AU - Dwarakanath, Vangipuram
AU - Arar, Mazan
AU - Biber, Jürg
AU - Murer, Heini
AU - Baum, Michel
PY - 1997/1
Y1 - 1997/1
N2 - Administration of glucocorticoids to neonates increases proximal tubule volume absorption by increasing glucose, bicarbonate, and amino acid transport. We have recently demonstrated that glucocorticoids may contribute to the maturational decrease in phosphate transport. This study examines the maturation of NaP(i)-6 [the regulated proximal tubule sodium-inorganic phosphate (Na-P(i)) transporter] mRNA and protein abundance and the mechanism for the decrease in phosphate transport by glucocorticoids. Weaned young rabbits (5 wk) had a 2-fold greater brush border membrane NaP(i)-6 protein abundance than that measured in adults. Renal cortical NaP(i)-6 mRNA abundance was comparable in neonates (less than 10 d of age) and adults. Renal brush border membrane vesicles from dexamethasone-treated neonatal rabbits (10 μg/100 g of body weight for 4 d) had a lower rate of Na-P(i) transport than vehicle-treated controls (46.8 ± 6.5 versus 71.0 ± 9.0 pmol 32P/10 s/mg of protein, p < 0.05). Abundance of NaP(i)-6 protein in brush border membrane vesicles was 3-fold lower in newborn rabbits treated with pharmacologic doses of dexamethasone than in vehicle-treated controls. NaP(i)-6 mRNA abundance was the same in both groups. NaP(i)-1, a brush border membrane phosphate transporter which is also an anion channel, mRNA, and protein abundance was not affected by glucocorticoids. These data demonstrate that there is a maturational decrease in NaP(i)-6 protein abundance and that glucocorticoids decrease neonatal phosphate transport, at least in part, by reducing the number of Na-P(i) transporters.
AB - Administration of glucocorticoids to neonates increases proximal tubule volume absorption by increasing glucose, bicarbonate, and amino acid transport. We have recently demonstrated that glucocorticoids may contribute to the maturational decrease in phosphate transport. This study examines the maturation of NaP(i)-6 [the regulated proximal tubule sodium-inorganic phosphate (Na-P(i)) transporter] mRNA and protein abundance and the mechanism for the decrease in phosphate transport by glucocorticoids. Weaned young rabbits (5 wk) had a 2-fold greater brush border membrane NaP(i)-6 protein abundance than that measured in adults. Renal cortical NaP(i)-6 mRNA abundance was comparable in neonates (less than 10 d of age) and adults. Renal brush border membrane vesicles from dexamethasone-treated neonatal rabbits (10 μg/100 g of body weight for 4 d) had a lower rate of Na-P(i) transport than vehicle-treated controls (46.8 ± 6.5 versus 71.0 ± 9.0 pmol 32P/10 s/mg of protein, p < 0.05). Abundance of NaP(i)-6 protein in brush border membrane vesicles was 3-fold lower in newborn rabbits treated with pharmacologic doses of dexamethasone than in vehicle-treated controls. NaP(i)-6 mRNA abundance was the same in both groups. NaP(i)-1, a brush border membrane phosphate transporter which is also an anion channel, mRNA, and protein abundance was not affected by glucocorticoids. These data demonstrate that there is a maturational decrease in NaP(i)-6 protein abundance and that glucocorticoids decrease neonatal phosphate transport, at least in part, by reducing the number of Na-P(i) transporters.
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U2 - 10.1203/00006450-199701000-00003
DO - 10.1203/00006450-199701000-00003
M3 - Article
C2 - 8979284
AN - SCOPUS:0031030910
SN - 0031-3998
VL - 41
SP - 20
EP - 24
JO - Pediatric Research
JF - Pediatric Research
IS - 1
ER -