Background and purpose: Rho/Rho-kinase signalling is involved in many cellular events, including some in the CNS. However, the role of this pathway in epilepsy has not yet been assessed. Therefore, we determined the effects of two Rho-kinase inhibitors, Y-27632 and fasudil, on seizures induced by pentylenetetrazole (PTZ) or maximal electroconvulsive shock (MES). Experimental approach: Effects of Y-27632 (5-10 mg kg À1 ) and fasudil (5-25 mg kg À1 ) on duration of myoclonic jerks, clonic and tonic convulsions, tonic hindlimb extensions and percentage of tonic convulsion index, as well as recovery latency for righting reflex were investigated in mice stimulated with PTZ (65 mg kg À1 ) or MES (50 Hz, 50 mA and 0.4 s). These inhibitors were also tested on a model of kindling induced by PTZ (35 mg kg À1 , for 11 days). Membrane and cytosolic levels of RhoA protein were measured in brain homogenates from kindled mice. Key results: Y-27632 and fasudil diminished onset of myoclonic jerks, clonic convulsions and tonic hindlimb extensions in mice given PTZ. These inhibitors suppressed the percentage of tonic convulsion index and recovery latency for righting reflex in the mice excited with MES. Western blotting demonstrated that Rho translocation to plasma membrane increased in the brain homogenates obtained from PTZ-kindled mice. However, the Rho-kinase inhibitors at the given doses did not change motor coordination of the mice. Conclusions and implications: Rho/Rho-kinase signalling may play a role in epilepsy induced by PTZ and MES. Furthermore, Rho-kinase inhibitors could be novel important antiepileptic agents.

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1 This study made use of a nitric oxide-sensitive electrode to examine possible means of generating nitric oxide from nitroxyl anion (NO 7 ) released upon the decomposition of Angeli's salt. 2 Our results show that copper ions (from CuSO 4 ) catalyze the rapid and e cient oxidation of nitroxyl to nitric oxide. Indeed, the concentrations of copper required to do so (0.1 ± 100 mM) are roughly 100-times lower than those required to generate equivalent amounts of nitric oxide from Snitroso-N-acetyl-D,L-penicillamine (SNAP). 3 Experiments with ascorbate (1 mM), which reduces Cu 2+ ions to Cu + , and with the Cu 2+ chelators, EDTA and cuprizone, and the Cu + chelator, neocuproine, each at 1 mM, suggest that the oxidation is catalyzed by copper ions in both valency states. 4 Some compounds containing other transition metals, i.e. methaemoglobin, ferricytochrome c and Mn(III)TMPyP, were much less e cient than CuSO 4 in catalyzing the formation of nitric oxide from nitroxyl, while FeSO 4 , FeCl 3 , MnCl 2 , and ZnSO 4 were inactive. 5 Of the copper containing enzymes examined, Cu-Zn superoxide dismutase and ceruloplasmin were weak generators of nitric oxide from nitroxyl, even at concentrations (2500 and 30 u ml 71 , respectively) vastly greater than are present endogenously. Two others, ascorbate oxidase (10 u ml 71 ) and tyrosinase (250 u ml 71 ) were inactive. 6 Our ®ndings suggest that a copper-containing enzyme may be responsible for the rapid oxidation of nitroxyl to nitric oxide by cells, but the identity of such an enzyme remains elusive.

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To determine the effects and underlying mechanisms of treatment with the ␤-receptor blockers nebivolol and metoprolol on penile endothelial function in apolipoprotein E (ApoE) Ϫ/Ϫ mice, wild-type (WT) and ApoE Ϫ/Ϫ mice were fed with a cholesterolrich diet for 7 weeks. ApoE Ϫ/Ϫ mice were treated with nebivolol (10 mg/kg/day) or metoprolol (90 mg/kg/day). Endothelial function of aortic and corpora cavernosal tissue was assessed by pharmacological stimulation with carbachol (endothelium dependent) or glycerol trinitrate (endothelium independent) in organ bath experiments. Atherosclerotic lesion formation was evaluated with oil-red staining, and modulation of reactive oxygen species (ROS) production was determined with lipid peroxidation. Heart rate, but not blood pressure, was decreased in nebivolol-and metoprolol-treated ApoE Ϫ/Ϫ mice (p Ͻ 0.01) compared with controls and WT mice without significant intergroup differences. Atherosclerotic lesion formation in the aortic root was increased in ApoE Ϫ/Ϫ mice (p Ͻ 0.01) with a more significant improvement in nebivolol-(p Ͻ 0.01) compared with metoprolol-treated mice (p Ͻ 0.05). Endothelium-dependent relaxation of the corpora cavernosa was significantly impaired in ApoE Ϫ/Ϫ mice (p Ͻ 0.05), which improved in nebivololversus metoprolol-treated mice. Efficacy of endothelium-dependent relaxation was comparable in aortic and penile tissue. Quantification of ROS production via lipid peroxidation revealed a significant reduction of superoxide anion production in nebivolol-treated (p Ͻ 0.05) but not metoprolol-treated mice compared with ApoE Ϫ/Ϫ controls. Nebivolol improves penile endothelial function as a surrogate of erectile function in ApoE Ϫ/Ϫ mice. These effects may be related to a reduction of ROS production, which is independent of heart rate reduction, because metoprolol did not increase endothelial function.