Activation of the skeletal muscle Ca 2+ release channel by the triazine dyes Cibacron Blue F3A-G and reactive Red 120

Abstract

Vesicle- 45Ca 2+ ion flux and planar lipid bilayer single-channel measurements have shown that the Ca 2+ release channel of skeletal muscle sarcoplasmic reticulum (SR) is activated by micromolar concentrations of Cibacron Blue F3A-G (Reactive Blue 2) and Reactive Red 120. Cibacron Blue increased the 45Ca 2+ efflux rate from heavy SR vesicles by apparently interacting with both the adenine nucleotide and caffeine activating sites of the channel. Dye-induced 45Ca 2+ release was inhibited by Mg 2+ and ruthenium red. In single channel recordings with the purified channel protein complex, Cibacron Blue increased the open time of the Ca 2+ release channel without an apparent change in the conductance of the main and subconductance states of the channel.