Pharmacological Profiling of K ATP Channel Modulators: An Outlook for New Treatment Opportunities for Migraine.

Migraine is a highly disabling pain disorder with huge socioeconomic and personal costs. It is genetically heterogenous leading to variability in response to current treatments and frequent lack of response. Thus, new treatment strategies are needed. A combination of preclinical and clinical data indicate that ATP-sensitive potassium (K ATP ) channel inhibitors could be novel and highly effective drugs in the treatment of migraine. The subtype Kir6.1/SUR2B is of particular interest and inhibitors specific for this cranio-vascular K ATP channel subtype may qualify as future migraine drugs. Historically, different technologies and methods have been undertaken to characterize K ATP channel modulators and, therefore, a head-to-head comparison of potency and selectivity between the different K ATP subtypes is difficult to assess. Here, we characterize available K ATP channel activators and inhibitors in fluorescence-based thallium-flux assays using HEK293 cells stably expressing human Kir6.1/SUR2B, Kir6.2/SUR1, and Kir6.2/SUR2A K ATP channels. Among the openers tested, levcromakalim, Y-26763, pinacidil, P-1075, ZM226600, ZD0947, and A-278637 showed preference for the K ATP channel subtype Kir6.1/SUR2B, whereas BMS-191095, NN414, and VU0071306 demonstrated preferred activation of the Kir6.2/SUR1 subtype. In the group of K ATP channel blockers, only Rosiglitazone and PNU-37783A showed selective inhibition of the Kir6.1/SUR2B subtype. PNU-37783A was stopped in clinical development and Rosiglitazone has a low potency for the vascular K ATP channel subtype. Therefore, development of novel selective K ATP channel blockers, having a benign side effect profile, are needed to clinically prove inhibition of Kir6.1/SUR2B as an effective migraine treatment.