9-Phenanthrol modulates postinhibitory rebound and afterhyperpolarizing potentials in an excitatory motor neuron of the medicinal leech.

Postinhibitory rebound (PIR) responses in leech dorsal excitatory motor neurons (cell DE-3) are eliminated by Ca channel blockers but also exhibit a strong dependence on extracellular Na. These features could be explained by a voltage-gated Ca current acting in concert with a Ca-activated nonspecific current (I). In vertebrates, I is associated with TRPM4 channels which are blocked selectively by 9-phenanthrol.