9-Phenanthrol

9-Phenanthrol is inhibitor of the transient receptor potential melastatin 4 (TRPM) channel, a Ca2+ -activated non-selective cation channel. (In Vitro) :In addition, 9-phenanthrol, lacking the chemical groups necessary for CFTR activation, also reversibly inhibited TRPM4 with a similar IC (50) . Channel inhibition was voltage independent. The IC (50) determined in the whole-cell and inside-out experiments were similar, suggesting a direct effect of the molecule. However, 9-phenanthrol was ineffective on TRPM5, the most closely related channel within the TRP protein family. We identify 9-phenanthrol as a TRPM4 inhibitor, without effects on TRPM5. It could be valuable in investigating the physiological functions of TRPM4, as distinct from those of TRPM5.