Effects Of Thiol Oxidants Induced Oxidative Stress On Modulating The Skeletal Type Ryanodine Receptor And On The Cross-linking With The Membrane Proteins

When human was in extreme environment under pathophysiological conditions,the redox of the body was elevated.Then regional oxidative stress followed intracellularly. Researches showed that some myocardial and skeletal muscle diseases were related to the oxidative damage of the ion channels on sarcoplasmic reticulum.The calcium release channel(ryanodine receptor,RyR) in sarcoplasmic reticulum was rich in sulfhydryls.As the target of oxidative stress,the calcium release channel was very sensitive to redox environment.Previous researches showed that RyRs were severely inhabited under oxidative stress conditions and the number of sulfhydryls greatly decreased.The function of RyRs was closely related to the interaction of RyR and other membrane proteins.Thus,we chose the interaction between those proteins as our main study to explore the influences of the oxidative stress to RyRs as well as its mechanism.In this study,high concentration of 1,4 NQ and Na₂SeO₃ was used to simulate oxidative stress,and the vesicle of sarcoplasmic reticulum(SR) and the calcium release channel(RyRl) of rabbit skeletal muscle were chosen as research objects. Many methods were used including[³H]-ryanodine binding assay,SDS-PAGE and western blotting,photon correlation spectroscopy(PCS) and DPH fluorescence polarization to explore the influences of oxidation modulators on the channel activity and the particle size of RyRl,the distribution of SR protein,and fluidity of SR membrane under oxidative stress.The activity of RyRl channel and the fluidity of SR membrane were lowered by high concentration of 1.4-NQ and Na₂SeO₃.Some macromolecular cross-linked complexes consisting of RyR,Ca²⁺ and myosin protein emerged on the SR membrane. More researches showed that DTT can decompose the cross-linked complexes. Na₂SeO₃ and 1,4 NQ led to cross-linked polymers of the RyRls,and increased the average particle size,while DTT can partially decompose the polymers.Above results showed that the inhibition of RyRl channel caused by the high concentration of oxidant modulators was probably due to the functional sulfhydryls which are responsible for the closure of the channels were oxidized,and the ensued incorrect cross-linking between proteins changed the structure of the calcium release channel.Furthermore,the enhancing interaction between RyRs probably affected the cooperativity of RyRs.