Hexachlorocyclohexane pesticides reduce survival and alter plasma membrane structure of Chinese hamster V79 cells.
We studied the cytotoxic effects of alpha-, beta-, gamma-, and delta-hexachlorocyclohexanes (HCCH) on the survival of Chinese hamster V79 cells using clonogenic assays. Lethal dose yielding 50% cell survival (LD50) suggests the following order of cytotoxicity: delta-(+)gamma-HCCH (LD50 4 micrograms/ml) (1:1, w/w, mixture) > delta-HCCH (LD50 6 micrograms/ml) > gamma-HCCH (LD50 13 micrograms/ml) > alpha-HCCH (LD50 approx. 35 micrograms/ml) >> beta-HCCH. Structural changes in plasma membranes prepared from HCCH-treated V79 cells at dose yielding 10% cell survival (LD10) were analyzed using Raman spectroscopy. Raman spectra of plasma membranes show bands at 2850, 2880-2890, and 2935 cm-1 in the C-H stretching region. The plot of the ratio (I2880-2890/I2850) vs temperature for control plasma membranes shows two transitions between -5 and 5 degrees C and between 12 and 20 degrees C. Plasma membranes prepared from gamma- and delta-HCCH-treated Chinese hamster V79 cells show single transitions between -4 and 11 degrees C and between -2 and 11 degrees C, respectively. These changes in the thermal transition properties suggest that both gamma- and delta-HCCH alter lipid and lipid-protein phases of the plasma membrane of V79 cells. Raman analysis of the amide I and amide III region spectra further suggest that delta-HCCH also alters the secondary structure and the environment of highly amidated segments of plasma membrane proteins. We suggest that the primary action of biologically active HCCH isomers is to disrupt the organization of the plasma membrane and that may affect cell viability.
Verma
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Department of Community Health, Tufts University School of Medicine, Boston, Massachusetts 02111.
Rastogi
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A
Lin
P S
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D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects* / Q000648:ultrastructure; D002470:Cell Survival / Q000187:drug effects*; D006224:Cricetinae; D003412:Cricetulus; D004305:Dose-Response Relationship, Drug; D001556:Hexachlorocyclohexane / Q000031:analogs & derivatives* / Q000494:pharmacology*; D007306:Insecticides / Q000494:pharmacology*; D013059:Spectrum Analysis, Raman; D013329:Structure-Activity Relationship; D013696:Temperature
D007306:Insecticides; D001556:Hexachlorocyclohexane