Mechanism for 193-nm laser radiation-induced effects on mammalian cells.
The cellular sites for damage in mammalian cells caused by 193-nm radiation from an argon fluoride excimer laser were investigated. The ability of Chinese hamster ovary cells to reduce a tetrazolium dye (MTT) was decreased to 37% of unirradiated control by 2.5 x 10(3) J/m2 of 193-nm radiation when measured either 4 or 24 h after irradiation. In contrast, inhibition of MTT reduction by 254-nm radiation which primarily causes DNA damage was not measurable using this assay at 4 h after exposure; at 24 h 45 J/m2 inhibited MTT reduction to 37% of control. An increase in plasma membrane permeability, detected by 51Cr release, was observed within 15 min of exposure to 193-nm radiation, whereas exposure to 254-nm radiation did not cause this immediate release of 51Cr. In control experiments, the mitochondrial poison, carbonyl cyanide m-chlorophenyl hydrazone, did not cause 51Cr release in the dark, indicating that the 193-nm radiation-induced increase in plasma membrane permeability was not subsequent to loss of mitochondrial function. [3H]-Arachidonic acid was released from C3H10T1/2 cells using low 193-nm fluences, whereas release of [3H]arachidonic acid using UVB (290-32 nm) radiation required cytotoxic fluences. DNA does not appear to be a major site of 193 nm-induced cellular damage because alkali-labile sites were not detected in cells exposed on ice to up to 2 x 10(4) J/m2 of 193-nm radiation. These results indicate that 193-nm radiation produces primary damage on the level of the plasma membrane.
Kochevar
I E
IE
Wellman Laboratories, Department of Dermatology, Massachusetts General Hospital, Harvard Medical School, Boston 02114.
Walsh
A A
AA
Held
K D
KD
Gallo
R L
RL
Mirro
J
J
D000818:Animals; D001095:Arachidonic Acids / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000528:radiation effects; D002478:Cells, Cultured / Q000528:radiation effects*; D006224:Cricetinae; D003412:Cricetulus; D004247:DNA / Q000528:radiation effects; D007834:Lasers; D051379:Mice; D008809:Mice, Inbred C3H; D013778:Tetrazolium Salts / Q000378:metabolism; D013844:Thiazoles / Q000378:metabolism
D001095:Arachidonic Acids; D013778:Tetrazolium Salts; D013844:Thiazoles; D004247:DNA; C022616:thiazolyl blue