DMCA
Sodium-Calcium Exchange in Intracellular Calcium Handling of Human Airway Smooth Muscle
BibTeX
@MISC{Sathish_sodium-calciumexchange,
author = {Venkatachalem Sathish and Michael A. Thompson and Christina M. Pabelick and Gary C and Y. S. Prakash},
title = {Sodium-Calcium Exchange in Intracellular Calcium Handling of Human Airway Smooth Muscle},
year = {}
}
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Abstract
Enhanced airway contractility following inflammation by cytokines such as tumor necrosis factor alpha (TNFa) or interleukin-13 (IL-13) involves increased intracellular Ca 2+ ([Ca 2+] i) levels in airway smooth muscle (ASM). In ASM, plasma membrane Ca 2+ fluxes form a key component of [Ca 2+]i regulation. There is now growing evidence that the bidirectional plasma membrane Na + /Ca 2+ exchanger (NCX) contributes to ASM [Ca 2+]i regulation. In the present study, we examined NCX expression and function in human ASM cells under normal conditions, and following exposure to TNFa or IL-13. Western blot analysis showed significant expression of the NCX1 isoform, with increased NCX1 levels by both cytokines, effects blunted by inhibitors of nuclear factor NF-kB or mitogen-activated protein kinase. Cytokine-mediated increase in NCX1 involved enhanced transcription followed by protein synthesis. NCX2 and NCX3 remained undetectable even in cytokinestimulated ASM. In fura-2 loaded human ASM cells, NCX-mediated inward Ca 2+ exchange as well as outward exchange (measured as rates of change in [Ca 2+]i) was elicited by altering extracellular Na + and Ca 2+ levels. Contribution of NCX was verified by measuring [Na +]i using the fluorescent Na + indicator SBFI. NCX-mediated inward exchange was verified by demonstrating prevention of rising [Ca 2+] i or falling [Na +] i in the presence of the NCX inhibitor KBR7943. Inward exchangemode NCX was increased by both TNFa and IL-13 to a greater extent than outward exchange. NCX siRNA transfection substantially blunted outward exchange and inward exchange modes. Finally, inhibition of NCX expression or function
Keyphrases
intracellular calcium handling human airway smooth muscle sodium-calcium exchange outward exchange ncx expression ncx-mediated inward ca extracellular na intracellular ca enhanced transcription key component cytokine-mediated increase fluorescent na indicator sbfi smooth muscle ncx1 isoform significant expression ncx1 level asm ca western blot analysis normal condition inward exchange mode human asm cell tumor necrosis factor alpha nuclear factor nf-kb fura-2 loaded human asm cell mitogen-activated protein kinase ncx-mediated inward exchange present study ncx inhibitor kbr7943 bidirectional plasma membrane na ca protein synthesis ncx sirna transfection plasma membrane ca
