DTNB oxidation effects on T-type Ca<SUP>2+</SUP> channel isoforms

초록

Redox regulation is one of the ubiquitous mechanisms to modulate ion channels. We here investigated how 5,5'-dithio-bis (2-nitrobenzoic acid), a cysteine specific oxidizing reagent, modulates Ca(v)3.1 and Ca(v)3.2 T-type Ca2+ channels expressed in Xenopus oocytes. Application of the reagent inhibited Ca(v)3.1 and Ca(v)3.2 currents in a dose-dependent manner. The oxidizing reagent (1 mM) reduced the peak amplitude of Ca(v)3.1 and Ca(v)3.2 currents by similar to 50% over 2-3 minutes and the decreased currents were fully recovered upon washout of it. The reagent slowed the activation and inactivation kinetics of Ca(v)3.1, Ca(v)3.2, and Ca(v)3.3 channel currents. Notably, the reagent positively shifted both activation and steady-state inactivation curves of Ca(v)3.1, while it did not those of Ca(v)3.2. Utilizing chimeric channels from Ca(v)3.1 and Ca(v)3.2, we localized the domains III and IV of Ca(v)3.1 responsible for the positive shifts of channel activation and steady-state inactivation. These findings provide hints relevant to the electrophysiological and molecular mechanisms accounting for the oxidative regulation of T-type channels.

키워드