Food restriction increases the protection of erythrocytes against the hemolysis induced by peroxyl radicals.

We have investigated the susceptibility to peroxidation of erythrocytes from young, adult and old ad libitum (AL) fed, as well as from adult and old food restricted rats, measuring the rate of hemolysis under controlled peroxidative condition. Food restriction has been applied on an every-other-day (EOD) schedule starting from the age of 3.5 months. The oxidation of red blood cells by molecular oxygen was performed in an aqueous suspension using the azo-compound 2-2'-azo-bis-(2-amidinopropane)hydrochloride (AAPH) as the free radical initiator. Several parameters were calculated from the time-dependent curve of AAPH induced hemolysis. The time required to achieve 50% hemolysis decreased with aging and this decrease was prevented by food restriction. The lag time, which reflects the capacity of the cell to buffer free radicals, was longer in young than in old AL fed animals also this impairment was almost completely prevented in EOD fed animals. The same beneficial effect of food restriction was observed considering the maximal amount of hemolysis attained with the dose of AAPH applied and the time necessary to reach this level. The general picture emerging from the present study is that erythrocyte membranes from EOD fed rats are better protected, than those from AL fed ones, against damages caused by peroxidation. This effect may be due to a difference in the chemical composition of the erythrocyte membranes as it was found in other organs.