Serotonergic-induced ion currents in cleaving sea urchin embryos

Summary

Using the whole-cell voltage clamp technique on early sea urchin embryos at different stages of the cell cycle, we showed that agonists of 5-HT receptor subtypes induce inward currents. The current induced by 5-HT₃ receptor agonists is dose dependent and reverses between −25 and +15 mV suggesting, it is carried by nonspecific ion channels. 5-HT₃ receptor agonists showed more pronounced effects when administered during cleavage furrow formation. The effects are accompanied by the increase of steady-state conductance and calcium current activity. These results suggest that serotonergics and ion channel activity play a role in the regulation of cellular events during cleavage division in the early sea urchin embryo, supporting the idea of a proto-synapse between blastomeres.

Key words:

• Neurotransmitters
• Ca²⁺ currents
• 5HT receptors
• cleavage division
• protosynapse