TY - JOUR T1 - Biochemical and Electrophysiological Studies on the Mechanism of Action of PNU-151774E, A Novel Antiepileptic Compound JF - Journal of Pharmacology and Experimental Therapeutics JO - J Pharmacol Exp Ther SP - 1151 LP - 1159 VL - 288 IS - 3 AU - P. Salvati AU - R. Maj AU - C. Caccia AU - M. A. Cervini AU - M. G. Fornaretto AU - E. Lamberti AU - P. Pevarello AU - G. A. Skeen AU - H. S. White AU - H. H. Wolf AU - L. Faravelli AU - M. Mazzanti AU - E. Mancinelli AU - M. Varasi AU - R. G. Fariello Y1 - 1999/03/01 UR - http://jpet.aspetjournals.org/content/288/3/1151.abstract N2 - PNU-151774E [(S)-(+)-2-(4-(3-fluorobenzyloxy)benzylamino)propanamide methanesulfonate], a new anticonvulsant that displays a wide therapeutic window, has a potency comparable or superior to that of most classic anticonvulsants. PNU-151774E is chemically unrelated to current antiepileptics. In animal seizure models it possesses a broad spectrum of action. In the present study, the action mechanism of PNU-151774E has been investigated using electrophysiological and biochemical assays. Binding studies performed with rat brain membranes show that PNU-151774E has high affinity for binding site 2 of the sodium channel receptor, which is greater than that of phenytoin or lamotrigine (IC50, 8 μM versus 47 and 185 μM, respectively). PNU-151774E reduces sustained repetitive firing in a use-dependent manner without modifying the first action potential in hippocampal cultured neurons. In the same preparation PNU-151774E inhibits tetrodotoxin-sensitive fast sodium currents and high voltage-activated calcium currents under voltage-clamp conditions. These electrophysiological activities of PNU-151774E correlate with its ability to inhibit veratrine and KCl-induced glutamate release in rat hippocampal slices (IC50, 56.4 and 185.5 μM, respectively) and calcium inward currents in mouse cortical neurons. On the other hand, PNU-151774E does not affect whole-cell γ-aminobutryic acid- and glutamate-induced currents in cultured mouse cortical neurons. These results suggest that PNU-151774E exerts its anticonvulsant activity, at least in part, through inhibition of sodium and calcium channels, stabilizing neuronal membrane excitability and inhibiting transmitter release. The possible relevance of these pharmacological properties to its antiepileptic potential is discussed. The American Society for Pharmacology and Experimental Therapeutics ER -