ADAPTATION OF THE BLOOD ANTIOXIDANT DEFENSE-MECHANISMS OF SHEEP WITH A GENETIC LESION RESULTING IN LOW RED-CELL GLUTATHIONE CONCENTRATIONS

Finnish Landrace sheep with a genetic lesion which results in restrict ed cysteine transport across the red cell membrane have total glutathi one concentrations in their red blood cells that are approximately 40% of those in normal sheep of the same breed. However, dimethyldisulphi de-challenged red blood cells from both phenotypes produce an ESR-spin adduct at similar rates. The resistance of the low glutathione phenot ype red cells to oxidant challenge is reflected by increases in the ac tivities of antioxidant enzymes. Sheep with a genotypic disorder in cy steine transport may be a suitable model for studying the genetic expr ession of antioxidant enzymes in response to oxidant loads.