Abstract
Key antioxidant defense reactions in RBCs are linked to nicotinamide adenine dinucleotide (NAD(+)) and nicotinamide adenine dinucleotide phosphate (NADP(+)). The ratio of reduced (NAD(P)H) to total pyridine nucleotide pool [(NAD(P)(T) i.e. NAD(P)H plus NAD(P)(+)], which is known as redox potential, reflects the redox status of erythrocytes. Through the utilization of a spectrophotometric cycling assay, the NAD(+) and NADP(+) redox potentials were determined in erythrocytes from normal Saudi subjects and those with sickle cell disease (SCD). The sickle erythrocytes NADH/NAD(T) ratio (0.386) was reduced compared to the normal ratio (0.464). This reduction appears to be due to a significant increase in oxidized NAD(+) in sickle RBCs. However, the value of the redox potential of erythrocytes in Saudi subjects with SCD is slightly higher than that reported for comparable African Americans. Although the high fetal hemoglobin is the main factor in the amelioration of the clinical course exhibited by Saudi sickle cell patients, it is assumed that the slight improvement in the redox potential may play a part in this process. This is supported by a relatively uninhibited glycolytic pathway in the erythrocytes of Saudi subjects with SCD with a higher level of NADH than their African American counterparts.