The main objective of this investigation was to study the effect of
salicylate on platelet mitochondrial
monoamine oxidase (
MAO) activity isolated from blood of two patients with
Reye's syndrome. Comparative studies were made with hospitalized children without
Reye's syndrome (n = 27) and healthy children (n = 19) serving as controls. Platelet
MAO was measured by a radioenzymatic technique with [14C]
tyramine as a substrate. The results of this study showed that
salicylate (1.0 mM) caused an appreciable inhibition of the platelet
MAO activity of patients with
Reye's syndrome at the onset of the illness. This was demonstrated by a greater than 50% reduction in
enzyme maximum velocity (Vmax) value. The
salicylate MAO-inhibitory effect was maintained throughout the duration of the illness.
Salicylate had only a minimal
MAO-inhibitory effect on platelets isolated from blood of recovered
Reye's syndrome patients, healthy controls, and non-Reye's hospitalized children, and no apparent effect on
enzyme Vmax values. These preliminary findings suggest that
salicylate-induced mitochondrial injury may affect
MAO function in children with
Reye's syndrome.