Ruthenium Red

Ruthenium red is a strong inhibitor of Ca²⁺ transport in mitochondrial, in erythrocyte membrane and in sarcoplasmic reticulum (SR) of rabbit skeletal muscle, with the K_m of 4.5 μM and 2.0 mM for the two Ca²⁺-binding sites [1].

By kinetic experiments, there are two high-affinity Ca²⁺-binding sites face the cytoplasmic portion of the SR membranes, which are located in helical segments clustered in the transmembrane domain of Ca²⁺-ATPase, forming a Ca²⁺ channel.

SR vesicles were incubated with 10 μM-⁴⁵Ca²⁺ and various ruthenium red concentrations for 15 min before being filtered for ⁴⁵Ca counting. The titration curve of Ca²⁺ binding showed two well-differentiated saturating effects with the K_m of 4.5 μM and 2.0 mM for the two Ca²⁺-binding sites. The ability of SR vesicles to bind Ca²⁺ was decreased by micromolar ruthenium red concentrations [1].

In the investigation of the ability of inhibiting caspsaicin-induced plasma extravasation in the rat trachea, ruthenium red can reduce the amount of plasma extravasation in dose-dependently, with a dose of 5 μmol/kg of completely inhibiting [2].

Reference:

[1] Corbalan-Garcia S, Teruel J A, Gomez-Fernandez J C. Characterization of Ruthenium Red-binding sites of the Ca²⁺-ATPase from sarcoplasmic reticulum and their interaction with Ca2+-binding sites [J]. Biochem J. 1992, 287(3): 767-774.

[2] Brokaw J J, White G W. Characterization of Ruthenium Red as an Inhibitor of Neurogenic Inflammation in the Rat Trachea [J]. Gen Pharmac. 1995, 26(2): 327-331.