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Effects of prenatal Betamethesone (Beta) exposure and unilateral nephrectomy on sodium uptake in ovine renal proximal tubule cells from young adult male sheep
Author(s) -
Su Yixin,
Bi Jianli,
Tang Lijun,
Figueroa Jorge P,
Rose James C
Publication year - 2012
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.26.1_supplement.1102.3
Subject(s) - medicine , endocrinology , nephron , kidney , offspring , chemistry , nephrectomy , stimulation , ouabain , sodium , biology , pregnancy , organic chemistry , genetics
Prenatal exposure to clinically relevant doses of Beta reduces nephron number in animals. Reductions in nephron number in early life increase the risk for impaired renal function following a second insult to the kidney. The present study was designed to examine whether antenatal betamethasone exposure at 80–81 days of gestation would impact sodium uptake by RPTC from adult rams. We also wished to determine if antenatal glucocorticoid exposure combined with a second insult (unilateral nephrectomy) would alter Na+ uptake by RPTC from adult rams. RPTC were isolated from intact or unilaterally nephrectomized 1‐yr‐old male vehicle‐treated (N=3) and Beta‐treated (N=7) offspring and cultured for 7–10 days. The fluorescence dye sodium green was employed to determine cytoplasmic Na+ uptake. In the presence of the Na+/K+ ATPase inhibitor ouabain, Na+ uptake in RPTC was evaluated while exposed to different Na+ concentrations from 30 to 140 mmol/L. Cellular Na+ uptake was expressed as the percent change of fluorescence emission of the dye monitored at excitation 507 nm, emission 532 nm. Prenatal steroid exposure increased basal Na+ uptake by 69% compared with vehicle treatment. (F=4.1, P<0.05) Na+ uptake was 70% greater in cells from Beta compared with cells from vehicle exposed sheep after Ang II (10–11M) stimulation (F=5.65, P<0.05). Following nephrectomy Na+ uptake was reduced 44% in vehicle (F=4.63, P<0.05) and 87% in Beta RPTC; (F=11.62, P<0.001) however cells from the Beta exposed animals still took up more Na+ than cells from the vehicle treated sheep under basal and Ang II stimulated conditions. These data suggest that prenatal Beta increases Na+ uptake by RPTC and the increased uptake persists after an acute reduction in nephron number in young adult male sheep. This may explain, at least in part, impaired Na+ excretion induced by antenatal Beta exposure. Supported by NIH grants HD 17644 and HD 47584.