ANTIOXIDATIVE VITAMINS IN PREMATURELY AND MATURELY BORN INFANTS

Postnatally a rapid change occurs from a relatively hypoxic to a relat ively hyperoxic environment, especially during artificial ventilation with all risks of ROS-formation. Among the non enzymatic antioxidative strategies the vitamins E, C, A and B-2 are of major importance. Vita min E is considered the most important radical scavenging vitamin of t he lipid soluble compartment. Hereby vitamin E itself is converted int o a radical which is handed over to vitamin C and glutathione into the water soluble compartment. The vitamin E content of the fetus increas es with the fetal fat mass mainly during the last trimester of pregnan cy. Placenta is only slightly permeable to lipid soluble vitamins. Vit amin E deficiency may rapidly develop typically at about 6-8 weeks of age. Vitamin E is able to prolong significantly the onset of retinopat hic changes during oxygen therapy and may prevent intraventricular hem orrhage. Vitamin C is together with glutathione a major representative of the non enzymatic antioxidative system in the water soluble compar tment. The best determinant of the vitamin C status is its concentrati on in leukocytes. Vitamin C reduces iron to the divalent state which s upports the hydroxyl radical formation (Haber-Weiss reaction). This sh ould be considered mainly in cases of intraventricular hemorrhage. Vit amin B-2 acts mainly as cofactor of glutathione reductase which keeps glutathione in the reduced state. It can therefore be considered an in direct antioxidative vitamin. Vitamin B-2 is destroyed by light. Photo therapy has been recognized as a cause of riboflavin deficiency. Vitam in A comprises all retinols with properties like trans-retinol. Retino l storage in the fetal liver increases during late pregnancy. In both, premature and mature newborns, the serum concentrations amount to onl y about 50% of those of their mothers. Vitamin A has a paramount impor tance for fetal lung development because the individual surfactant pro teins are selectively regulated by retinoic acid.