NDT Advance Access originally published online on July 18, 2009
Nephrology Dialysis Transplantation 2009 24(11):3306-3312; doi:10.1093/ndt/gfp354
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Low extracellular Ca2+: a mediator of endothelial inflammation
1 Renal Physiology Laboratory, Department of Nephrology and Hypertension, Meir Medical Center, Kfar-Saba 2 Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel
Correspondence and offprint requests to: Gloria Rashid; E-mail: gloriar{at}clalit.org.il
| Abstract |
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Background. Recent studies have suggested that vitamin D and an imbalance in calcium homeostasis may have an impact on the cardiovascular system. The aim of this study was to assess the impact of different concentrations of extracellular Ca2+ on human umbilical vein cord endothelial cells (HUVEC) by measuring its effect on parameters involved in the pathogenesis of vascular inflammatory responses.
Methods. HUVEC were grown in the 3.5, 4.5 or 5.8 mg/dL concentration of extracellular Ca2+ for 2–3 weeks. Expression of adhesion molecules was analysed by flow cytometry. Endothelial nitric oxide synthase (eNOS), receptor of advanced glycation end-product (RAGE) and interleukin-6 (IL-6) mRNA expressions were determined by real-time PCR. eNOS, inhibitor kappa B
(I
B
) and phosphorylated I
B
protein levels by Western blot, eNOS activity by conversion of [14C]-arginine to [14C]-citrulline, IL-6 and osteoprotegerin (OPG) secretion by ELISA and DNA-binding activity of nuclear factor kappa B (NF
B)-p65 were assayed colorimetrically in nuclear extracts.
Results. In the presence of low Ca2+ (3.5 mg/dL), protein expressions and activity of eNOS were diminished, while the protein expressions of intercellular adhesion molecule-1 (ICAM-1), as well as the mRNA expressions of RAGE and IL-6, were elevated. The protein secretions of IL-6 and OPG were also stimulated in low Ca2+ concentration. At this concentration, the DNA-binding activity of NF
B was enhanced, probably due to the decreased level of I
B
.
Conclusions. These results suggest that lower extracellular ionized Ca2+ may play a relevant role in modifying endothelial cells functions.
Keywords: calcium; endothelial cells; NF
B
Received for publication: 31. 3.09
Accepted in revised form: 26. 6.09