Nifedipine Increases Iron Content in WKPT-0293 Cl.2 Cells via Up-Regulating Iron Influx Proteins.

Shuang-Shuang Yu,Li-Rong Jiang,Yu-Fu Zhou,Juan Li,Yan Ling,Zhong-Ming Qian,Ya Ke

doi:10.3389/fphar.2017.00060

Shuang-Shuang Yu, Li-Rong Jiang + Show 5 more

Open Access

https://doi.org/10.3389/fphar.2017.00060

Copy DOI

Abstract

Nifedipine was reported to enhance urinary iron excretion in iron overloaded mice. However, it remains unknown how nifedipine stimulates urinary iron excretion in the kidney. We speculated that nifedipine might inhibit the TfR1/ DMT1 (transferrin receptor 1/divalent metal transporter1)-mediated iron uptake by proximal tubule cells in addition to blocking L-type Ca2+ channels, leading to an increase in iron in lumen-fluid and then urinary iron excretion. To test this hypothesis, we investigated the effects of nifedipine on iron content and expression of TfR1, DMT1 and ferroportin1 (Fpn1) in WKPT-0293 Cl.2 cells of the S1 segment of the proximal tubule in rats, using a graphite furnace atomic absorption spectrophotometer and Western blot analysis, respectively. We demonstrated for the first time that nifedipine significantly enhanced iron content as well as TfR1 and DMT1 expression and had no effect on Fpn1 levels in the cells. We also found that ferric ammonium citrate decreased TfR1 levels, increased Fpn1 expression and had no effect on DMT1 content, while co-treatment with nifedipine and FAC increase TfR1 and DMT1 expression and also had no effect on Fpn1 levels. These findings suggest that the nifedipine-induced increase in cell iron may mainly be due to the corresponding increase in TfR1 and DMT1 expression and also imply that the effects of nifedipine on iron transport in proximal tubule cells can not explain the increase in urinary iron excretion.

Highlights

Plasma iron is tightly bound to Tf, a 78-kDa circulating protein that is assumed to not cross the glomerulus filter, because of its low protein permeability (Aisen, 1994; Linder, 2013)
Western blot analysis demonstrated that co-treatment with nifedipine and Ferric Ammonium Citrate (FAC) led to a significant increase in transferrin receptor 1 (TfR1) (Figure 5A), divalent metal transporter 1 (DMT1) + divalent metal transporter1 without iron response element (IRE) (Figure 5B) and DMT1-IRE (Figure 5C) expression and had no effect on ferroportin 1 (Fpn1) expression (Figure 5D) in WKPT-0293 Cl.2 cells
We demonstrated for the first time that nifedipine treatment has a significant role in enhancing, rather than reducing iron content in WKPT-0293 Cl.2 cells of the S1 segment of the proximal tubule of normotensive Wistar-Kyoto rats (RPTC)

Summary

Introduction

Plasma iron is tightly bound to Tf, a 78-kDa circulating protein that is assumed to not cross the glomerulus filter, because of its low protein permeability (Aisen, 1994; Linder, 2013). Measurement of iron re-absorption in the rat kidney in vivo has shown that, under physiological conditions, about 0.4 mg iron is filtered daily and about 0.7% is excreted in the urine (Wareing et al, 2000). These novel data imply that the kidney plays a previously unsuspected role in systemic iron balance, and contributes to general iron homeostasis (Martines et al, 2013; Veuthey et al, 2014)

Objectives

Methods

Results

Conclusion