Nonselective cation channel activated by patch excision from lobster olfactory receptor neurons

Area of Science:

• Neuroscience
• Ion Channel Physiology
• Sensory Biology

Background:

• Olfactory receptor neurons (ORNs) play a crucial role in detecting odors.
• Ion channels are fundamental to neuronal function, including signal transduction in olfaction.
• Characterizing novel ion channels can elucidate sensory mechanisms.

Purpose of the Study:

• To characterize a nonselective cation channel found in spiny lobster ORNs.
• To investigate the channel's permeability, conductance, and voltage dependence.
• To understand the effects of divalent cations on channel activity and gating.

Main Methods:

• Utilized inside-out patch-clamp recordings from spiny lobster ORN membranes.
• Applied various monovalent (Na+, K+, Cs+) and divalent (Mg2+) cations at different concentrations.
• Performed voltage-clamp analysis to assess channel conductance and voltage dependence.

Main Results:

• Identified a 320 pS nonselective cation channel permeable to Na+, K+, and Cs+.
• Observed voltage-dependent block of Na+ permeation by millimolar internal divalent cations.
• Divalent cations also reduced channel opening frequency in a concentration-dependent manner, suggesting distinct gating and conductance sites.
• Evidence for a multi-ion pore and high permeability to external divalent cations was found.

Conclusions:

• The characterized channel exhibits properties consistent with a single entity mediating both monovalent and divalent cation flux.
• The findings demonstrate the presence and function of this cation channel in arthropods, expanding knowledge of its role in olfaction.
• Distinct cation binding sites influencing gating and conductance were identified, providing a deeper understanding of channel regulation.