Effects of Small Conductance Ca²⁺‐Activated Potassium Channel Agonists on SLEs in Varied Epilepsy Models, From Animal Slices to Pharmacoresistant Human Tissue

To assess the impact of SK channel agonists on seizure-like events (SLEs) in various seizure models in slices of the temporal cortex obtained from pharmacoresistant patients. SLEs were triggered by applying 4-aminopyridine (100 μM) to slices of the entorhinal cortex taken from both normal and pilocarpine-treated rats. Additionally, SLEs were induced in slices of the temporal cortex obtained from individuals who had undergone epilepsy surgery. In the case of human slices, SLEs were also provoked by increasing potassium levels along with the administration of either 4-AP (100 μM) or bicuculline (50 μM). The activation of SK2/3 channels by the compound CYPPA (n = 8) effectively prevented SLEs in slices from the brains of normal rats, pilocarpine-treated rats (n = 8), and in human cortex slices (n = 9) when SLEs were triggered by 4-AP. In human temporal cortex slices, CYPPA also demonstrated efficacy in preventing SLEs induced by an elevation in potassium concentration combined with bicuculline application (n = 5). SKA-31, exhibited efficacy in slices from normal rats (n = 8), rats treated with pilocarpine (n = 8), and in human slices (n = 7) when SLEs were provoked by 4-AP. However, its effectiveness was limited when applied to human tissue slices exposed to bicuculline and elevated potassium levels. The SK1 channel activator GW-542573X displayed only moderate anticonvulsant effects in the models under investigation. SK2 channels showed the highest effectiveness across the different epilepsy models. Sensitivity to the SK3 channel activator was found to be more pronounced compared to the other two activators studied.