Study On The Modulation Of Naphthoquinon And Selenium Compounds To The Skeletal Type Ryanodine Receptor

The idea that oxidative stress injures intracellular Ca²⁺mobilization and Ca²⁺ homeostasis has been widely accepted.Ryanodine receptor(RyR)is one of the most important intracellular calcium release channels and is the main target of oxidative stress.Previous studies have shown that different thiol oxidants can affect Ca²⁺ release mechanism of skeletal muscle sarcoplasmic reticulum(SR),and the production of superoxide(O₂^·-)was detected during the reaction.To study the effect of thiol oxidants such as naphthoquinon(NQ)and selenium (Se)on the skeletal type Ca²⁺release channel/ryanodine receptor(RyR1),generation of O₂^·-,initial rate of[³H]—ryanodine binding,release rate of Ca²⁺from SR,change of free thiols on RyR1 were detected to reveal the modulation of these reagents or O₂^·-to the channel activities.Moreover,SDS-PAGE and western blotting were used to find the effect of these oxidants on proteins in SR.The results showed that these thiol-specific oxidants could generate O₂^·-when interacting with the system.These oxidants were observed to active RyR1 at lower concentrations and to inhibit the channel at higher concentrations.Further more,the serious oxidative stress which caused by NQ or Se compounds could induce the protein cross-linking.At the same time the number of free thiols decreased with the increase in the reagents concentration.However,superoxide dismutase(SOD)could partially or completely reverse all of these effects.The results indicate that besides the directly oxidation of oxidants,O₂^·-also participates in the modulation of channel activity and the oxidation of free thiols on RyR1.It is proposed that ROS may play a role as intracellular signal molecule that participates in modulating intracellular Ca²⁺ mobility and the Ca²⁺homeostasis by oxidizing different functional free thiol groups on RyR.This is likely to underline the protein-centered molecular bases of the cellular damnification responses to an intracellular oxidative stress.