KT-5823

Tofogliflozin is a sodium-glucose cotransporter 2 inhibitor widely used to treat type 2 diabetes mellitus, but it also exhibits cardio-protective effects. This study investigated the vasodilatory action of tofogliflozin using rabbit femoral artery rings pre-contracted with phenylephrine (1 μM). The results showed the concentration-dependent induction of vasodilation by tofogliflozin, a response that remained unchanged following endothelial removal, pretreatment with the nitric oxide synthase inhibitor L-NAME (100 μM), or the inhibition of low- and intermediate-conductance Ca²⁺-activated K⁺ channels using apamin (1 μM) in combination with TRAM-34 (1 μM). Furthermore, pretreatment with the voltage-dependent K⁺ (Kv) channel inhibitor 4-AP (3 mM) reduced the vasodilatory effects of tofogliflozin whereas pretreatment with the ATP-sensitive K⁺ channel inhibitor glibenclamide (10 μM) or the large-conductance Ca²⁺-activated K⁺ channel inhibitor paxilline (1 μM) did not. Notably, our findings indicated that Kv7.X, rather than Kv1.5 or Kv2.1, is the primary Kv subtype involved in tofogliflozin-induced vasodilation. The vasodilatory effects of tofogliflozin were also significantly inhibited in femoral arterial rings pretreated with the sarco/endoplasmic reticulum Ca²⁺-ATPase (SERCA) pump inhibitors thapsigargin (1 μM) and cyclopiazonic acid (10 μM). Tofogliflozin-induced vasodilation was unaltered in arterial rings exposed to the adenylyl cyclase inhibitor SQ 22536 (50 μM), the protein kinase A (PKA) inhibitor KT 5720 (1 μM), and the protein kinase G inhibitor KT 5823 (1 μM) whereas it was effectively reduced by the soluble guanylyl cyclase (sGC) inhibitor ODQ (10 μM). These findings suggest that tofogliflozin-induced vasodilation is mediated by the activation of the SERCA pump, the sGC/cGMP pathway, and Kv channels.