ROLE OF INOSINE IN PREVENTION OF METHEMOGLOBINEMIA IN THE PIG - IN-VITRO STUDIES

Methaemoglobin reductase activity was studied in pig, human and cattle erythrocytes incubated in a medium containing glucose or inosine as N ADH generator. With glucose, methaemoglobin reduction was very fast in human, less so in cattle and slowest in pig erythrocytes. With inosin e, pig red cells reduced methaemoglobin more rapidly than human red ce lls and in bovine erythrocytes the enzyme activity was undetectable. I n intact red cells the ability to reduce methaemoglobin depends on the amount of NADH the cell can produce with glucose or inosine utilizati on. The results show that pig red blood cells utilize inosine as the N ADH generator for enzymatic reduction of methaemoglobin. The greater e fficiency of pig red cells could be due to several factors: better ino sine transport, more active metabolic pathway for inosine utilization (so that more NADH is produced), or greater MR activity when NADH is i n excess. In any case, the high rate of methaemoglobin reduction could explain the lower prevalence of methaemoglobinaemia in pigs than in c attle.