Low levels of the pesticide, delta-hexachlorocyclohexane, lyses human erythrocytes and alters the organization of membrane lipids and proteins as revealed by Raman spectroscopy.
We studied the nature of the interaction of delta-hexachlorocyclohexane (delta-HCCH), a pesticide having a stereoisomeric structure similar to inositol, with red blood cells. Cell survival data, measured as percent of hemoglobin released by delta-HCCH, show that the cell lysis increases with post exposure time. delta-HCCH at 55-60 micrograms/ml causes about 70% cell lysis after 24 h of exposure. The nature of interaction of delta-HCCH with membrane components was evaluated by studying the thermotropic transitions and protein structure of ghosts using Raman spectroscopy. Control ghosts show transitions with onset/completion temperatures 30 degrees C/38 degrees C (high temperature transition) and 3 degrees C/10 degrees C (middle temperature transition) when monitored by the I2935/I2850 ratio. The interaction of delta-HCCH drastically broadens the high temperature transition and shifts it to the temperature range of 10-29 degrees C. The plots of (I2880-90/I2850) vs. temperature show two transitions for control ghosts, one extending from -10 degrees C to 3 degrees C (lower temperature transition) and the other from about 7 degrees C to about 15 degrees C (middle temperature transition). Ghosts lysed with delta-HCCH shows only a single and a very broad transition in the range of about -3 degrees C to about 15 degrees C. These changes in the thermal transition properties suggest that delta-HCCH alters lipid and lipid-protein phases of erythrocyte membranes. The comparison of Raman spectra in the amide I and III regions of erythrocyte ghosts and purified band 3 with several amidated compounds reveals that cytoskeleton proteins contain highly amidated residues (probably glutamine and asparagine). The interaction of delta-HCCH with erythrocytes drastically alters the environment of these amidated residues indicating the involvement of cytoskeleton proteins. We conclude that the interaction of delta-HCCH with red blood cells disrupt membrane structure and change the environment of cytoskeleton proteins that could cause cell lysis.
Verma
S P
SP
Department of Community Health, Tufts University School of Medicine, Boston, MA 02111.
Singhal
A
A
D000577:Amides / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D004910:Erythrocyte Membrane / Q000187:drug effects / Q000378:metabolism; D004912:Erythrocytes / Q000187:drug effects*; D006461:Hemolysis / Q000187:drug effects*; D001556:Hexachlorocyclohexane / Q000633:toxicity*; D006801:Humans; D008563:Membrane Lipids / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D013059:Spectrum Analysis, Raman; D013696:Temperature
D000577:Amides; D008563:Membrane Lipids; D008565:Membrane Proteins; D001556:Hexachlorocyclohexane