M084 causes cell cycle arrest and inhibits voltage-gated Na+ and K+ channels in neuronal N2A cells

The effects of M084, an inhibitor of transient receptor potential (TRP) channels TRPC4 and TRPC5, on cell proliferation, voltage-gated K+ (Kv) channels and voltage-gated Na+ (Nav) channels were investigated in mouse neuronal N2A cells. Cell proliferation was measured by MTT assay and trypan blue exclusion test. Mitochondrial membrane potential was measured using JC-1 as a fluorescent probe. Cell cycle and ion channel activities were studied, respectively, using flow cytometry and voltage-clamp method. M084 (10-100 mu M) concentration- dependently suppressed cell proliferation; M084 at 100 mu M also arrested cell cycle at the G1 phase, and caused a decrease in mitochondrial membrane potential. The anti-proliferative effect of M084 was not mitigated by dorsomorphine (AMPK inhibitor), sodium salicylate (NF-kappa B inhibitor) and SP600125 (JNK inhibitor), but was alleviated by SB203580 (p38 inhibitor). M084 (3-100 mu M) suppressed Nav and Kv currents in a concentration- dependent fashion with IC50 values of 9.1 and 29.2 mu M, respectively. M084 (30 mu M) caused left-shifts in inactivation curves of both Nav and Kv currents, and diminished peak amplitude of current injection-triggered membrane potential overshoot. In conclusion, M084 suppressed neuronal cell growth and inhibited their Nav and Kv channels.