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Role of transferrin in the stimulation of Na, K-ATPase induced by low K~(+) in Madin Darby canine kidney cells

Yin Wu, Zhou Xiaoming, Cai Baochang

Department of Pharmacy,Nanjing University of Traditional Chinese Medicine.Nanjing 210029,Jiangsu；USA

Abstract

We found that serum was essential for low K~(+) to induce an increase in Na, K-ATPase binding sites as quantified by ouabain factor binding assays. In an attempt to identify which component was critical, we screened EGF, IGF1, PGE1 and transferrin to identify which one can replace serum. We discovered that transferrin was the single most important factor that mimicked about 80% to 90% of the effect of serum. Transferrin potentiated the effect of low K~(+)-induced increase in #alpha#_(1)-promoter activity, #alpha#_(1)- and #beta#_(1)-subunit protein abundance of the Na, K-ATPase. In the presence of transferrin, low K~(+) enhanced cellular uptake of iron approximately by 70%. Inhibitio of intracellular iron activity by deferoxamine (30#mu#mol/L) abrogated the effect of low K~(+). We conclude that stimulation of the Na, K-ATPase by low K~(+) is critically dependent on transferrin. The effect of transferrin is mediated by increased iron transport.

Key words: Na;K-ATPase;Low potassium;Transferrin iron;MDCK cells

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Citing This Article：

Yin Wu, Zhou Xiaoming, Cai Baochang. Role of transferrin in the stimulation of Na, K-ATPase induced by low K~(+) in Madin Darby canine kidney cells. Acta Physiol Sin 2003; 55 (4): (in Chinese with English abstract).