Abstract
N-acetylcysteine (NAC) has been known not only to stimulate synthesis of glutathione but also to affect the gene regulation. In our study, effects of NAC on the cytotoxicity of cadmium (Cd) were examined in LLC-PK1 cells. Preincubation and subsequent incubation with 1 mM NAC almost completely suppressed Cd-induced cellular damage evaluated either by trypan blue exclusion or lactate dehydrogenase leakage. This almost complete protection required the presence of NAC during Cd exposure. Treatment with 1 mM NAC increased the intracellular glutathione level approximately 2-fold. Inhibition of this increase by buthionine sulfoximine did not abolish the protection by NAC. One mM NAC also suppressed Cd-induced increase of c-Fos protein although NAC alone did not change the protein content. The inhibition of transcriptions by actinomycin D did not affect the protection by NAC. Thus, NAC-induced protection appeared to be independent of glutathione level or the transcriptional activation of genes including c-fos. However, treatment with NAC markedly lowered the uptake of Cd into cells although it did not affect the efflux clearly. Addition of NAC during the exposure to Cd suppressed Cd-induced cellular damage but the suppression decreased when the duration of the exposure without NAC increased. These results suggest that NAC-induced protection against Cd cytotoxicity is mainly due to the lowered uptake of Cd into the cells.
Footnotes
-
Send reprint requests to: Dr. Masato Matsuoka, Department of Environmental Toxicology, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishi-ku, Kitakyushu 807-8555, Japan.
- Abbreviations:
- NAC
- N-acetyl-l-cysteine
- Cd
- cadmium
- AP-1
- activator protein 1
- PBS
- phosphate-buffered saline
- BSO
- l-buthionine-(S,R)-sulfoximine
- AcD
- actinomycin D
- LDH
- lactate dehydrogenase
- TBS-T
- Tris-buffered saline containing 0.05% Tween 20
- Received December 30, 1997.
- Accepted May 12, 1998.
- The American Society for Pharmacology and Experimental Therapeutics
JPET articles become freely available 12 months after publication, and remain freely available for 5 years.Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page.
|