Hydrogen sulfide inhibits Cav3.2 T-type Ca2+ channels

Area of Science:

• Physiology
• Neuroscience
• Biochemistry

Background:

• Hydrogen sulfide (H2S) is increasingly recognized as a crucial physiological signaling molecule.
• Ion channels are identified as key targets mediating H2S actions.
• The specific effects of H2S on T-type calcium channels remain largely unexplored.

Purpose of the Study:

• To investigate the impact of H2S on T-type calcium channels.
• To determine which subtypes of T-type calcium channels are affected by H2S.
• To elucidate the mechanism underlying H2S modulation of these channels.

Main Methods:

• Patch-clamp electrophysiology was employed to study channel activity.
• Heterologous expression systems (HEK293 cells) were used to express specific channel subtypes (Cav3.1, Cav3.2, Cav3.3).
• Experiments involved applying H2S donors (NaHS) and chelating agents (Zn2+).

Main Results:

• H2S selectively inhibited Cav3.2 T-type channels, leaving Cav3.1 and Cav3.3 unaffected.
• Inhibition of Cav3.2 channels by H2S required the extracellular residue H191, also critical for Zn2+ binding.
• Chelation of Zn2+ prevented and reversed H2S-induced inhibition, suggesting H2S enhances Zn2+ affinity.
• Native T-type channels in sensory neurons, primarily Cav3.2, were also inhibited by H2S.

Conclusions:

• The T-type calcium channel Cav3.2 is a novel target for H2S regulation.
• H2S modulation of Cav3.2 channels is dependent on extracellular Zn2+ binding.
• The observed inhibition of Cav3.2 channels by H2S does not account for the pain-associated effects of H2S.