Increase in cystine transport activity and glutathione level in mouse peritoneal macrophages exposed to oxidized low-density lipoprotein.

The transport of cystine has been investigated in mouse peritoneal macrophages incubated with oxidized low-density lipoprotein (oxi-LDL; low-density lipoprotein, LDL). The transport activity for cystine was potently induced by oxi-LDL but not by native or acetylated LDL. The response of the cells to oxi-LDL was dependent on the extent of oxidative modification of LDL. The transport activity for other amino acids was not induced by oxi-LDL. GSH content increased in macrophages incubated with oxi-LDL and this increase was accounted for by the induction of the cystine transport activity because the increase was completely blocked by glutamate or homocysteate which shared the transport system for cystine and thus inhibited the uptake of cystine competitively.