99 THE DIFFERENTIAL EXPRESSION OF CALCIUM-RELATED PROTEINS BY HYPOXIC STRESS IN THE DUODENUM, KIDNEY, AND PLACENTA OF PREGNANT RATS

Abstract

Preeclampsia is a pregnancy-specific disease characterized by the de novo development of concurrent hypertension, proteinuria, and oxidative stress in placenta. Hypoxia occurs during the development of placenta in the first trimester and is implicated in trophoblast differentiation. Oxidative stress, resulting from deficient remodeling of spiral arteries, is an important inducer of preeclampsia. The potassium-dependent sodium/calcium exchangers including NCKX3 and NCX1 play critical roles in the transport of intracellular calcium that is exchanged with extracellular sodium ions. Calcium-related proteins, NCXs, calbindin, calcium pumping proteins (TRPV5-6, PMCA1b), transcripts are abundant in the smooth muscle, uterus, aorta, and intestine. The expressions of calcium-related proteins in the kidney, duodenum, and placenta after hypoxic stress in rats at gestation Day 19.5 (GD 19.5) were examined by real-time PCR and Western blot analysis. Hypoxic condition did not change fetal weight; however, it significantly increased the weight of placenta compared to normoxic condition. In GD 19.5, renal NCKX3 and TRPV6 expressions were increased, whereas the levels of NCX1 were decreased in hypoxic rats compared with normoxic pregnant rats. The expressions of CaBP-9k, TRPV5, and PMCA1b were not altered in normoxic or hypoxic rat tissues. Duodenal expressions of CaBP-9k, TRPV5-6, and PMCA1 were decreased in hypoxic rats, whereas NCXs were not changed. The transcripts of NCKX3, TRPV5-6, and PMCA1b were highly expressed in the placenta of hypoxic rat. Taken together, the expressions of renal, duodenal, and placental calcium-related proteins appear to be modulated by hypoxia-induced oxidative stress, implying that calcium-related proteins may be involved in preeclamptic oxidative stress.