Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
2601804 | Toxicology Letters | 2008 | 6 Pages |
Abstract
The effect of N-(4-hydroxyphenyl) arachidonoyl-ethanolamide (AM404), a drug commonly used to inhibit the anandamide transporter, on intracellular free Ca2+ levels ([Ca2+]i) and viability was studied in human MG63 osteosarcoma cells using the fluorescent dyes fura-2 and WST-1, respectively. AM404 at concentrations â¥5 μM increased [Ca2+]i in a concentration-dependent manner with an EC50 value of 60 μM. The Ca2+ signal was reduced partly by removing extracellular Ca2+. AM404 induced Mn2+ quench of fura-2 fluorescence implicating Ca2+ influx. The Ca2+ influx was sensitive to La3+, Ni2+, nifedipine and verapamil. In Ca2+-free medium, after pretreatment with 1 μM thapsigargin (an endoplasmic reticulum Ca2+ pump inhibitor), AM404-induced [Ca2+]i rise was abolished; and conversely, AM404 pretreatment totally inhibited thapsigargin-induced [Ca2+]i rise. Inhibition of phospholipase C with U73122 did not change AM404-induced [Ca2+]i rise. At concentrations between 10 and 200 μM, AM404 killed cells in a concentration-dependent manner presumably by inducing apoptotic cell death. The cytotoxic effect of 50 μM AM404 was partly reversed by prechelating cytosolic Ca2+ with BAPTA/AM. Collectively, in MG63 cells, AM404 induced [Ca2+]i rise by causing Ca2+ release from the endoplasmic reticulum in a phospholipase C-independent manner, and Ca2+ influx via L-type Ca2+ channels. AM404 caused cytotoxicity which was possibly mediated by apoptosis.
Related Topics
Life Sciences
Environmental Science
Health, Toxicology and Mutagenesis
Authors
Hong-Tai Chang, Chorng-Chih Huang, He-Hsiung Cheng, Jue-Long Wang, Ko-Long Lin, Pei-Te Hsu, Jeng-Yu Tsai, Wei-Chuan Liao, Yih-Chau Lu, Jong-Khing Huang, Chung-Ren Jan,