KMID : 0811720080120040177
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Korean Journal of Physiology & Pharmacology 2008 Volume.12 No. 4 p.177 ~ p.184
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Acidic pH-activated Cl? Current and Intracellular Ca2£« Response in Human Keratinocytes
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Park Su-Jung
Kwon Oh-Sang Eun Hee-Chul Chung Jin-Ho Earm Yung-E Kim Sung-Joon Choi Won-Woo
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Abstract
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The layers of keratinocytes form an acid mantle on the surface of the skin. Herein, we investigated the effects of acidic pH on the membrane current and [Ca2£«]c of human primary keratinocytes from foreskins and human keratinocyte cell line (HaCaT). Acidic extracellular pH (pHe¡Â5.5) activated outwardly rectifying Cl? current (ICl,pH) with slow kinetics of voltage-dependent activation. ICl,pH was potently inhibited by an anion channel blocker 4,4`-diisothiocyanostilbene-2,2`-disulphonic acid (DIDS, 73.5% inhibition at 1?M). ICl,pH became more sensitive to pHe by raising temperature from 24oC to 37oC. HaCaT cells also expressed Ca2£«-activated Cl? current (ICl,Ca), and the amplitude of ICl,Ca was increased by relatively weak acidic pHe (7.0 and 6.8). Interestingly, the acidic pHe (5.0) also induced a sharp increase in the intracellular [Ca2£«] (?[Ca2£«]acid) of HaCaT cells. The ?[Ca2£«]acid was independent of extracellular Ca2£«, and was abolished by the pretreatment with PLC inhibitor, U73122. In primary human keratinocytes, 5 out of 28 tested cells showed ?[Ca2£«]acid. In summary, we found ICl,pH and ?[Ca2£«]acid in human keratinocytes, and these ionic signals might have implication in pathophysiological responses and differentiation of epidermal keratinocytes.
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KEYWORD
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Keratinocyte, Extracellular pH, Anion channel, Intracellular calcium, pH-activated Cl- current
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