Biology subjects

An, J. R.

Publications and source records attributed to An, J. R..

2 recordsLinked to original sources

bioRxiv2026

Blockade of Kv3.1 by MK-801, a PCP-Derivative NMDA Receptor Inhibitor: Implications for Models of Schizophrenia

MK-801, a phencyclidine (PCP) derivative also known as dizocilpine, is a potent noncompetitive antagonist of the N-Methyl-D-aspartate receptor (NMDAr). The NMDAr plays a critical role in mediating excitatory synaptic transmission in the central nervous system (CNS) and is important in regulating synaptic plasticity, learning, and memory. MK-801 is known to induce schizophrenia-like phenotypes in animal models by blocking the NMDAr. Several studies have reported that the cognitive impairment associated with schizophrenia is linked to functional defects of ion channels in parvalbumin-positive GABAergic interneurons. Kv3.1 is a voltage-gated K+ (Kv) channel involved in the rapid repolarization of the action potential in neurons; it is richly expressed in parvalbumin-positive GABAergic interneurons and is associated with fast, repetitive spike generation. A decrease of Kv3.1 in the CNS has been reported to be associated with schizophrenia. In the present study, the effect of MK-801 on Kv3.1 was investigated using the whole-cell patch-clamp technique in Chinese hamster ovary (CHO) cells stably expressing Kv3.1. MK-801 caused a concentration-dependent inhibition of Kv3.1, with an IC50 of 10.81 M and a Hill coefficient of 0.89. The blocking potency was stronger at depolarized potentials, indicating a voltage-dependent block. MK-801 also produced a use-dependent block, inducing progressive inhibition with repeated stimulation at increased frequencies (1 Hz and 2 Hz), consistent with a delay in recovery from inactivation of Kv3.1 in the presence of MK-801. In addition, MK-801 induced a hyperpolarizing shift in the voltage dependence of the steady-state inactivation curve of Kv3.1. Taken together, these results indicate that MK-801 blocks Kv3.1 expressed in CHO cells in a concentration-, voltage-, and state-dependent manner. Given the importance of Kv3.1 in parvalbumin-positive, fast-spiking GABAergic interneurons, these findings suggest that MK-801 may alter the firing patterns of these inhibitory neurons, contributing to the onset and symptoms of schizophrenia.

pharmacology and toxicology↗

bioRxiv2024

The sodium-glucose cotransporter 2 inhibitor tofogliflozin induces vasodilation by activating Kv channels, the SERCA pump, and the sGC/cGMP pathway

OBJECTIVETofogliflozin is a sodium-glucose cotransporter 2 (SGLT2) inhibitor widely used to treat T2DM, but it also exhibits cardio-protective effects. This study investigated the vasodilatory action of tofogliflozin using rabbit femoral artery rings pre-contracted with phenylephrine. APPROACH AND RESULTSThe femoral artery quickly separated from the rabbit and fix it to the organ bath chamber. Subsequently, administer an inhibitor that modulates vascular tension in the rings or remove the endothelium to assess its impact on vasodilation. 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 (NOS) inhibitor L-NAME, or the inhibition of low- and intermediate-conductance Ca2+-activated K+ channels (SKCa and IKCa) using apamin in combination with TRAM-34. Furthermore, pretreatment with the voltage-dependent K+ (Kv) channel inhibitor 4-AP reduced the vasodilatory effects of tofogliflozin whereas pretreatment with the ATP-sensitive K+ (KATP) channel inhibitor glibenclamide or the large-conductance Ca2+-activated K+ (BKCa) channel inhibitor paxilline 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 and cyclopiazonic acid (CPA). Tofogliflozin-induced vasodilation was unaltered in arterial rings exposed to the adenylyl cyclase inhibitor SQ 22536, the protein kinase A (PKA) inhibitor KT 5720, and the protein kinase G (PKG) inhibitor KT 582 whereas it was effectively reduced by the soluble guanylyl cyclase (sGC) inhibitor ODQ. CONCLUSIONSThese findings suggest that tofogliflozin-induced vasodilation is mediated by the activation of the SERCA pump, the sGC/cGMP pathway, and Kv channels, but not the PKA signaling pathway, other K+ channels, or endothelium-dependent mechanisms.

pharmacology and toxicology↗