Effects of reduced and oxidized glutathione on sphingomyelinase activity and contents of sphingomyelin and lipid peroxidation products in murine liver.

Like the phosphatidyl inositol cycle, the sphingomyelin cycle produces a series of the secondary messengers transmitting extracellular signals from the cytoplasmic membrane into the nucleus. Sphingomyelin, ceramide, sphingosine, sphingomyelinase, and ceramidase are the main components of the sphingomyelin cycle. In spite of numerous data on the functional properties of sphingomyelin cycle products, the activation mechanism for the key enzyme of the sphingomyelin cycle, sphingomyelinase (SMase), is not well understood.

Effect of bilirubin on lipid peroxidation, sphingomyelinase activity, and apoptosis induced by sphingosine and UV irradiation.

The effect of bilirubin (BR) on sphingomyelin cycle activity, lipid peroxidation (LPO), and apoptosis induced by sphingosine and UV irradiation has been studied in vivo. Neutral Mg(2+)-dependent sphingomyelinase (SMase) activity and LPO level were monitored in heart, kidney, and liver of mice after administration of BR. BR inhibited both LPO and SMase activities in heart and kidney.