• K2P (two-pore domain potassium channel)
• TREK (TWIK-Related K+ Channel)
• ion channel
• pain

• Animals
• Potassium Channels, Tandem Pore Domain/metabolism
• Potassium Channels, Tandem Pore Domain/agonists
• Humans
• Mice
• Rats
• Male
• HEK293 Cells
• Dose-Response Relationship, Drug
• Drug Discovery
• High-Throughput Screening Assays
• Analgesics/pharmacology
• Central Nervous System/metabolism
• Central Nervous System/drug effects
• Cricetulus

• physiology
• medical research

• Anti-Inflammatory Agents/pharmacology
• Anti-Inflammatory Agents/chemistry
• Analgesics/pharmacology
• Analgesics/chemistry
• Animals
• Plant Extracts/pharmacology
• Plant Extracts/chemistry
• Humans
• Mice
• Coriandrum/chemistry
• Molecular Docking Simulation
• Plants, Medicinal/chemistry
• Potassium Channel Blockers/pharmacology
• Potassium Channel Blockers/chemistry
• Male
• Tannins/pharmacology
• Tannins/chemistry

• R01AI168063 U.S. Department of Health & Human Services | NIH | National Institute of Allergy and Infectious Diseases (NIAID)
• R01 AI168063 NIAID NIH HHS
• U01AI160397 U.S. Department of Health & Human Services | NIH | National Institute of Allergy and Infectious Diseases (NIAID)
• GM130377 U.S. Department of Health & Human Services | NIH | National Institute of General Medical Sciences (NIGMS)
• R35 GM130377 NIGMS NIH HHS
• R323-2018-3674 Lundbeckfonden (Lundbeck Foundation)
• U01 AI160397 NIAID NIH HHS

• smooth muscle contractility
• two-pore domain potassium channels
• urinary bladder
• voiding dysfunction

• Animals
• Potassium Channels, Tandem Pore Domain/genetics
• Potassium Channels, Tandem Pore Domain/metabolism
• Potassium Channels, Tandem Pore Domain/deficiency
• Urinary Bladder/physiopathology
• Urinary Bladder/metabolism
• Urinary Bladder/pathology
• Mice, Knockout
• Muscle Contraction
• Muscle, Smooth/metabolism
• Muscle, Smooth/physiopathology
• Muscle, Smooth/pathology
• Male
• Female
• Hypertrophy
• Aging/metabolism
• Mice
• Mice, Inbred C57BL
• Age Factors
• Urination

• P30 NS048154 NINDS NIH HHS
• R01 DK121506 NIDDK NIH HHS
• UL1 TR001082 NCATS NIH HHS
• R01 DK129260 NIDDK NIH HHS
• R01 DK095817 NIDDK NIH HHS

• BL-1249
• K2P channels
• TREK1
• TRESK
• blood-brain barrier
• electrophysiology

• Humans
• Potassium Channels, Tandem Pore Domain/metabolism
• Endothelial Cells/metabolism
• Neuroinflammatory Diseases
• Brain/metabolism
• Cell Adhesion Molecules/metabolism

• TREK-1 (KCNK2) ion channels
• acute lung injury
• cytokines
• inflammation
• influenza virus

• Animals
• Humans
• Mice
• Acute Lung Injury/pathology
• Chemokine CXCL10/metabolism
• Influenza A virus
• Influenza, Human/pathology
• Interleukin-6/metabolism
• Lung/metabolism
• Orthomyxoviridae Infections/pathology
• Potassium Channels, Tandem Pore Domain/genetics
• Potassium Channels, Tandem Pore Domain/metabolism

• R01 HL151419 NHLBI NIH HHS
• R01 HL131526 NHLBI NIH HHS
• R01 HL146821 NHLBI NIH HHS
• R01 HL134346 NHLBI NIH HHS
• K08 HL118118 NHLBI NIH HHS
• HHS | NIH | National Heart, Lung, and Blood Institute (NHLBI)
• U.S. Department of Defense (DOD)

Inhibitory potassium channels of the TREK1/TRAAK family are integrators of multiple stimuli, including temperature, membrane stretch, polyunsaturated fatty acids and pH. How these signals affect the gating of these channels is the subject of intense research. We have previously identified a cytoplasmic domain, pCt, which plays a major role in controlling channel activity. Here, we use pharmacology to show that the effects of pCt, arachidonic acid, and extracellular pH converge to the same gate within the channel. Using a state-dependent inhibitor, fluoxetine, as well as natural and synthetic openers, we provide further evidence that the “up” and “down” conformations identified by crystallography do not correspond to open and closed states of these channels.

• allostery
• extracellular pH
• openers
• pore gating
• two-pore domain potassium channels

The TWIK-related potassium channel (TREK-1) can be regulated by different stimuli. However, it is not clear whether some antiarrhythmics affect the activity of TREK-1. In the present study, the effect of bepridil on the TREK-1 currents is investigated.

In a TREK-1 stably-expressed HEK-293 cell line (HEK-TREK-1), U251MG cells, and isolated mouse ventricular myocytes, the TREK-1 current and action potentials were recorded by the patch-clamp technique. The standard voltage protocol was a 200 ms constant potential at 20 mV, followed bya 500 ms ramp from –90 to +20 mV (HEK-TREK-1) or +80 mV (U251MG cells and myocytes) every 10 s. The currents at +20 mV or +80 mV were used for analysis. The docking study of bepridil’s binding model in the TREK-1 channel was performed using the Swissdock web service.

In HEK-TREK-1 cells, BL1249 induced a significantly large outwardly rectifying current with similar baseline TREK-1 current characteristic, with a reversal potential (−70 mV). The concentration of half-maximal activation (EC₅₀) of BL1249 was 3.45 µM. However, bepridil decreased the baseline TREK-1 currents, with a concentration of half-maximal inhibition (IC₅₀) 0.59 µM and a Hill coefficient of 1.1. Also, bepridil inhibited BL1249-activated TREK-1 currents, with an IC₅₀ 4.08 µM and a Hill coefficient of 3.22. The outside-out patch-clamp confirmed bepridil inhibited BL1249-activated TREK-1 currents. In U251MG cells and myocytes, BL1249 activated outwardly rectifying endogenous TREK-1 currents, which could be inhibited by bepridil. BL1249 (10 µM) could decrease the peak value and reduce the duration of the action potential. Bepridil (10 µM) prolonged the duration of action potential of myocytes. The docking study revealed that bepridil might affect the K⁺ pore domain and the M4 modulator pocket.

Bepridil may be a blocker for the TREK-1K⁺channel at a clinically therapeutic concentration, providing a new mechanism of TREK-1 regulation and bepridil's antiarrhythmic effect.

• TWIK-related potassium channel
• antiarrhythmic drug
• bepridil
• patch clamp

The two-pore domain K_2P subunits form background (leak) potassium channels, which are characterized by constitutive, although not necessarily constant activity, at all membrane potential values. Among the fifteen pore-forming K_2P subunits encoded by the KCNK genes, the three members of the TREK subfamily, TREK-1, TREK-2, and TRAAK are mechanosensitive ion channels. Mechanically induced opening of these channels generally results in outward K⁺ current under physiological conditions, with consequent hyperpolarization and inhibition of membrane potential-dependent cellular functions. In the past decade, great advances have been made in the investigation of the molecular determinants of mechanosensation, and members of the TREK subfamily have emerged among the best-understood examples of mammalian ion channels directly influenced by the tension of the phospholipid bilayer. In parallel, the crucial contribution of mechano-gated TREK channels to the regulation of membrane potential in several cell types has been reported. In this review, we summarize the general principles underlying the mechanical activation of K_2P channels, and focus on the physiological roles of mechanically induced hyperpolarization.

• KCNK10
• KCNK2
• KCNK4
• TREK1
• TREK2
• mechanosensitive
• membrane tension
• potassium channel
• stretch

• Animals
• Cell Membrane/metabolism
• Humans
• Lipid Bilayers/metabolism
• Membrane Potentials/physiology
• Physical Phenomena
• Potassium Channels, Tandem Pore Domain/metabolism

• Formalin
• Inflammatory pain
• Mechanical allodynia
• Mechanical hyperalgesia
• TREK-1

Pulmonary arterial hypertension (PAH) is an aggressive vascular remodeling disease that carries a high morbidity and mortality rate. Treprostinil (Remodulin) is a stable prostacyclin analogue with potent vasodilatory and anti-proliferative activity, approved by the FDA and WHO as a treatment for PAH. A limitation of this therapy is the severe subcutaneous site pain and other forms of pain experienced by some patients, which can lead to significant non-compliance. TWIK-related potassium channels (TREK-1 and TREK-2) are highly expressed in sensory neurons, where they play a role in regulating sensory neuron excitability. Downregulation, inhibition or mutation of these channels leads to enhanced pain sensitivity. Using whole-cell patch-clamp electrophysiological recordings, we show, for the first time, that treprostinil is a potent antagonist of human TREK-1 and TREK-2 channels but not of TASK-1 channels. An increase in TASK-1 channel current was observed with prolonged incubation, consistent with its therapeutic role in PAH. To investigate treprostinil-induced inhibition of TREK, site-directed mutagenesis of a number of amino acids, identified as important for the action of other regulatory compounds, was carried out. We found that a gain of function mutation of TREK-1 (Y284A) attenuated treprostinil inhibition, while a selective activator of TREK channels, BL-1249, overcame the inhibitory effect of treprostinil. Our data suggests that subcutaneous site pain experienced during treprostinil therapy may result from inhibition of TREK channels near the injection site and that pre-activation of these channels prior to treatment has the potential to alleviate this nociceptive activity.

• BL-1249
• K2P channels
• TASK-1 channel
• TREK-1 (tandem of pore domain in a weak inwardly rectifying K channel (Twik)-related K channels)
• TREK-2 channels
• pulmonary arterial hypertension
• treprostinil (PubChem CID: 6918140)

Leak currents, defined as voltage and time independent flows of ions across cell membranes, are central to cellular electrical excitability control. The K_2P (KCNK) potassium channel class comprises an ion channel family that produces potassium leak currents that oppose excitation and stabilize the resting membrane potential in cells in the brain, cardiovascular system, immune system, and sensory organs. Due to their widespread tissue distribution, K_2Ps contribute to many physiological and pathophysiological processes including anesthesia, pain, arrythmias, ischemia, hypertension, migraine, intraocular pressure regulation, and lung injury responses. Structural studies of six homomeric K_2Ps have established the basic architecture of this channel family, revealed key moving parts involved in K_2P function, uncovered the importance of asymmetric pinching and dilation motions in the K_2P selectivity filter (SF) C-type gate, and defined two K_2P structural classes based on the absence or presence of an intracellular gate. Further, a series of structures characterizing K_2P:modulator interactions have revealed a striking polysite pharmacology housed within a relatively modestly sized (~70 kDa) channel. Binding sites for small molecules or lipids that control channel function are found at every layer of the channel structure, starting from its extracellular side through the portion that interacts with the membrane bilayer inner leaflet. This framework provides the basis for understanding how gating cues sensed by different channel parts control function and how small molecules and lipids modulate K_2P activity. Such knowledge should catalyze development of new K_2P modulators to probe function and treat a wide range of disorders.

• K(2P) channel
• M2 and M4 helix transmembrane motions
• polysite pharmacology
• selectivity filter C-type gate

• Analgesics
• Central Nervous System
• Ion Channels
• Pain
• Peripheral Nervous System
• Potassium Channels

Two-pore domain potassium (K2P) channels carry background (or leak) potassium current and play a key role in regulating resting membrane potential and cellular excitability. Accumulating evidence points to a role for K2Ps in human pathophysiologies, most notably in pain and migraine, making them attractive targets for therapeutic intervention. However, there remains a lack of selective pharmacological tools. The aim of this work was to apply a “target class” approach to investigate the K2P superfamily and identify novel activators across all the described subclasses of K2P channels. Target class drug discovery allows for the leveraging of accumulated knowledge and maximizing synergies across a family of targets and serves as an additional approach to standard target-based screening. A common assay platform using baculovirus (BacMam) to transiently express K2P channels in mammalian cells and a thallium flux assay to determine channel activity was developed, allowing the simultaneous screening of multiple targets. Importantly, this system, by allowing precise titration of channel function, allows optimization to facilitate the identification of activators. A representative set of channels (THIK-1, TWIK-1, TREK-2, TASK-3, and TASK-2) were screened against a library of Food and Drug Administration (FDA)-approved compounds and the LifeArc Index Set. Activators were then analyzed in concentration–response format across all channels to assess selectivity. Using the target class approach to investigate the K2P channels has enabled us to determine which of the K2Ps are amenable to small-molecule activation, de-risk multiple channels from a technical point of view, and identify a diverse range of previously undescribed pharmacology.

• K2P
• assay
• ion channel
• potassium channel
• screening

• PKA phosphorylation
• PKC phosphorylation
• TREK-1 channels
• neuropathic pain

• contractility
• excitability
• ion channel
• smooth muscle
• urinary bladder

• Animals
• Humans
• Ion Channels/metabolism
• Large-Conductance Calcium-Activated Potassium Channels/metabolism
• Muscle Contraction/physiology
• Muscle, Smooth/metabolism
• Myocytes, Smooth Muscle/metabolism
• Urinary Bladder/metabolism

• P20 DK123971 NIDDK NIH HHS
• R01 DK106964 NIDDK NIH HHS

• K2P channel
• TASK channels
• TREK channels
• cryptic binding site
• inhalational anesthetic
• negatively charged activators

Bradykinin (BK), a hormone inducing pain and inflammation, is known to inhibit potassium M-currents (I_M) and to increase the excitability of the superior cervical ganglion (SCG) neurons by activating the Ca²⁺-calmodulin pathway. M-current is also reduced by muscarinic agonists through the depletion of membrane phosphatidylinositol 4,5-biphosphate (PIP₂). Similarly, the activation of muscarinic receptors inhibits the current through two-pore domain potassium channels (K2P) of the “Tandem of pore-domains in a Weakly Inward rectifying K⁺ channel (TWIK)-related channels” (TREK) subfamily by reducing PIP₂ in mouse SCG neurons (mSCG). The aim of this work was to test and characterize the modulation of TREK channels by bradykinin. We used the perforated-patch technique to investigate riluzole (RIL) activated currents in voltage- and current-clamp experiments. RIL is a drug used in the palliative treatment of amyotrophic lateral sclerosis and, in addition to blocking voltage-dependent sodium channels, it also selectively activates the K2P channels of the TREK subfamily. A cell-attached patch-clamp was also used to investigate TREK-2 single channel currents. We report here that BK reduces spike frequency adaptation (SFA), inhibits the riluzole-activated current (I_RIL), which flows mainly through TREK-2 channels, by about 45%, and reduces the open probability of identified single TREK-2 channels in cultured mSCG cells. The effect of BK on I_RIL was precluded by the bradykinin receptor (B₂R) antagonist HOE-140 (d-Arg-[Hyp³, Thi⁵, d-Tic⁷, Oic⁸]BK) but also by diC₈PIP₂ which prevents PIP₂ depletion when phospholipase C (PLC) is activated. On the contrary, antagonizing inositol triphosphate receptors (IP₃R) using 2-aminoethoxydiphenylborane (2-APB) or inhibiting protein kinase C (PKC) with bisindolylmaleimide did not affect the inhibition of I_RIL by BK. In conclusion, bradykinin inhibits TREK-2 channels through the activation of B₂Rs resulting in PIP₂ depletion, much like we have demonstrated for muscarinic agonists. This mechanism implies that TREK channels must be relevant for the capture of information about pain and visceral inflammation.

• PIP2
• TREK currents
• bradykinin
• perforated patch
• riluzole
• sympathetic neurons

• Action Potentials/drug effects
• Animals
• Bradykinin/administration & dosage
• Bradykinin/analogs & derivatives
• Bradykinin/genetics
• Bradykinin/metabolism
• Bradykinin/pharmacology
• Cells, Cultured
• Humans
• Mice
• Muscarinic Agonists/pharmacology
• Neurons/drug effects
• Neurons/pathology
• Patch-Clamp Techniques
• Phosphatidylinositol 4,5-Diphosphate/genetics
• Phosphatidylinositol 4,5-Diphosphate/metabolism
• Potassium/metabolism
• Potassium Channels, Tandem Pore Domain/genetics
• Potassium Channels, Tandem Pore Domain/metabolism
• Receptors, Muscarinic/genetics
• Riluzole/pharmacology
• Sodium Channel Blockers/pharmacology
• Superior Cervical Ganglion/drug effects
• Sympathetic Nervous System/drug effects
• Sympathetic Nervous System/metabolism
• Type C Phospholipases

A better understanding of the gating of TREK two pore domain potassium (K2P) channels and their activation by compounds such as the negatively charged activator, flufenamic acid (FFA) is critical in the search for more potent and selective activators of these channels. Currents through wild-type and mutated human K2P channels expressed in tsA201 cells were measured using whole-cell patch-clamp recordings in the presence and absence of FFA. Mutation of the TM2.6 residue of TREK-1 to a phenylalanine (G171F) and a similar mutation of TM4.6 (A286F) substantially reduced current through TREK-1 channels. In complementary experiments, replacing the natural F residues at the equivalent position in TRESK channels, significantly enhanced current. Known, gain of function mutations of TREK-1 (G137I, Y284A) recovered current through these mutated channels. This reduction in current could be also be reversed pharmacologically, by FFA. However, an appropriate length MTS (MethaneThioSulfonate) cross-linking reagent (MTS14) restricted the activation of TREK-1_A286C channels by repeated application of FFA. This suggests that the cross-linker stabilises the channel in a conformation which blunts FFA activation. Pharmacologically reversible mutations of TREK channels will help to clarify the importance of these channels in pathophysiological conditions such as pain and depression.

TREK-1 is the most studied background K_2P channel. Its main role is to control cell excitability and maintain the membrane potential below the threshold of depolarization. TREK-1 is multi-regulated by a variety of physical and chemical stimuli which makes it a very promising and challenging target in the treatment of several pathologies. It is mainly expressed in the brain but also in heart, smooth muscle cells, endocrine pancreas, and prostate. In the nervous system, TREK-1 is involved in many physiological and pathological processes such as depression, neuroprotection, pain, and anesthesia. These properties explain why many laboratories and pharmaceutical companies have been focusing their research on screening and developing highly efficient modulators of TREK-1 channels. In this review, we summarize the different roles of TREK-1 that have been investigated so far in attempt to characterize pharmacological tools and new molecules to modulate cellular functions controlled by TREK-1.

• K2P
• TREK-1
• arrhythmia
• ion channel
• modulators
• neurological disorders
• potassium

The current knowledge of electrogenesis in mesenchymal stromal cells (MSCs) remains scarce. Earlier, we demonstrated that in MSCs from the human adipose tissue, transduction of certain agonists involved the phosphoinositide cascade. Its pivotal effector PLC generates DAG that can regulate ion channels directly or via its derivatives, including arachidonic acid (AA). Here we showed that AA strongly hyperpolarized MSCs by stimulating instantly activating, outwardly rectifying TEA-insensitive K⁺ channels. Among AA-regulated K⁺ channels, K2P channels from the TREK subfamily appeared to be an appropriate target. The expression of K2P channels in MSCs was verified by RT-PCR, which revealed TWIK-1, TREK-1, and TASK-5 transcripts. The TREK-1 inhibitor spadin antagonized the electrogenic action of AA, which was simulated by the channel activator BL 1249. This functional evidence suggested that TREK-1 channels mediated AA-dependent hyperpolarization of MSCs. Being mostly silent at rest, TREK-1 negligibly contributed to the “background” K⁺ current. The dramatic stimulation of TREK-1 channels by AA indicates their involvement in AA-dependent signaling in MSCs.

• TREK-1 channel
• arachidonic acid
• mesenchymal stromal cells
• patch clamp

• K2P channel
• TREK channel
• electrophysiology
• ion channel chemical biology

Two-pore domain potassium channels (K2P) constitute major candidates for the regulation of background potassium currents in mammalian cells. Channels of the TREK subfamily are also well positioned to play an important role in sensory transduction due to their sensitivity to a large number of physiological and physical stimuli (pH, mechanical, temperature). Following our previous report describing the molecular expression of different K2P channels in the vagal sensory system, here we confirm that TREK channels are functionally expressed in neurons from the mouse nodose ganglion (mNG). Neurons were subdivided into three groups (A, Ah and C) based on their response to tetrodotoxin and capsaicin. Application of the TREK subfamily activator riluzole to isolated mNG neurons evoked a concentration-dependent outward current in the majority of cells from all the three subtypes studied. Riluzole increased membrane conductance and hyperpolarized the membrane potential by approximately 10 mV when applied to resting neurons. The resting potential was similar in all three groups, but C cells were clearly less excitable and showed smaller hyperpolarization-activated currents at -100 mV and smaller sustained currents at -30 mV. Our results indicate that the TREK subfamily of K2P channels might play an important role in the maintenance of the resting membrane potential in sensory neurons of the autonomic nervous system, suggesting its participation in the modulation of vagal reflexes.

• Action Potentials/drug effects
• Animals
• Capsaicin/pharmacology
• Cells, Cultured
• Humans
• Ion Channel Gating/drug effects
• Mice
• Neurons/drug effects
• Neurons/metabolism
• Nodose Ganglion/cytology
• Potassium Channels, Tandem Pore Domain/antagonists & inhibitors
• Potassium Channels, Tandem Pore Domain/metabolism
• Riluzole/pharmacology
• Tetrodotoxin/toxicity

• Secretaría de Estado de Investigación, Desarrollo e Innovación
• European Regional Development Fund
• Consellería de Cultura, Educación e Ordenación Universitaria, Xunta de Galicia

• Animals
• CHO Cells
• Cell Line
• Cricetulus
• Dose-Response Relationship, Drug
• Ganglia, Spinal/drug effects
• Ganglia, Spinal/metabolism
• HEK293 Cells
• Humans
• Molecular Structure
• Neurons/drug effects
• Neurons/metabolism
• Potassium Channels, Tandem Pore Domain/agonists
• Rats
• Structure-Activity Relationship

• BB/J000930/1 Biotechnology and Biological Sciences Research Council

Gastrointestinal (GI) motility disorders such as irritable bowel syndrome (IBS) can occur when coordinated smooth muscle contractility is disrupted. Potassium (K⁺) channels regulate GI smooth muscle tone and are key to GI tract relaxation, but their molecular and functional phenotypes are poorly described. Here we define the expression and functional roles of mechano-gated K_2P channels in mouse ileum and colon. Expression and distribution of the K_2P channel family were investigated using quantitative RT-PCR (qPCR), immunohistochemistry and confocal microscopy. The contribution of mechano-gated K_2P channels to mouse intestinal muscle tension was studied pharmacologically using organ bath. Multiple K_2P gene transcripts were detected in mouse ileum and colon whole tissue preparations. Immunohistochemistry confirmed TREK-1 expression was smooth muscle specific in both ileum and colon, whereas TREK-2 and TRAAK channels were detected in enteric neurons but not smooth muscle. In organ bath, mechano-gated K_2P channel activators (Riluzole, BL-1249, flufenamic acid, and cinnamyl 1-3,4-dihydroxy-alpha-cyanocinnamate) induced relaxation of KCl and CCh pre-contracted ileum and colon tissues and reduced the amplitude of spontaneous contractions. These data reveal the specific expression of mechano-gated K_2P channels in mouse ileum and colon tissues and highlight TREK-1, a smooth muscle specific K_2P channel in GI tract, as a potential therapeutic target for combating motility pathologies arising from hyper-contractility.

• K2P channels
• TREK-1
• colon
• contractility
• ileum
• motility
• smooth muscle

Polymodal K_2P (KCNK) thermo- and mechanosensitive TREK¹ potassium channels, generate ‘leak’ currents that regulate neuronal excitability, respond to lipids, temperature, and mechanical stretch, and influence pain, temperature perception, and anesthetic responses^1–3. These dimeric voltage-gated ion channel (VGIC) superfamily members have a unique topology comprising two pore forming regions per subunit^4–6. Contrasting other potassium channels, K_2Ps use a selectivity filter ‘C-type’ gate^7–10 as the principal gating site. Despite recent advances^3,11,12, K_2Ps suffer from a poor pharmacologic profile limiting mechanistic and biological studies. Here, we describe a new small molecule TREK activator class that directly stimulates the C-type gate by acting as molecular wedges that restrict interdomain interface movement behind the selectivity filter. Structures of K_2P2.1(TREK-1) alone with two selective K_2P2.1(TREK-1) and K_2P10.1(TREK-2) activators, an N-aryl-sulfonamide, ML335, and a thiophene-carboxamide, ML402, define a cryptic binding pocket unlike other ion channel small molecule binding sites and, together with functional studies, identify a cation-π interaction that controls selectivity. Together, our data unveil a previously unknown, druggable K_2P site that stabilizes the C-type gate ‘leak mode’ and provide direct evidence for K_2P selectivity filter gating.

The ongoing research on pioneering drug candidates for the overactive bladder (OAB) aimed to overcome the limitations of currently licensed pharmacotherapies, such as antimuscarinics, β3-adrenergic agents, and botulinum neurotoxin, has been reviewed performing a systematic literature review and web search. The review covers the exploratory agents alternative to available medications for OAB and that may ultimately prove to be therapeutically useful in the future management of OAB patients based on preclinical and early clinical data. It emerges that many alternative pharmacological strategies have been discovered or are under investigation in disease-oriented studies. Several potential therapeutics are known for years but still find obstacles to pass the clinical stages of development, while other completely novel compounds, targeting new pharmacological targets, have been recently discovered and show potential to translate into clinical therapeutic agents for idiopathic and neurogenic OAB syndrome. The global scenario of investigational drugs for OAB gives promise for the development of innovative therapeutics that may ultimately prove effective as first, combined or second-line treatments within a realistic timescale of ten years.

• Detrusor overactivity
• Drug therapy
• Lower urinary tract symptoms
• Overactive bladder
• Urinary incontinence

• Fenamates/pharmacology
• HEK293 Cells
• Humans
• Ion Channel Gating/drug effects
• Ion Channel Gating/physiology
• Mutation/physiology
• Potassium Channels, Tandem Pore Domain/agonists
• Potassium Channels, Tandem Pore Domain/chemistry
• Potassium Channels, Tandem Pore Domain/physiology
• Protein Structure, Secondary

• BB/J00037X/1 Biotechnology and Biological Sciences Research Council
• BB/J000930/1 Biotechnology and Biological Sciences Research Council

K_2P (KCNK) potassium channels generate “leak” potassium currents that strongly influence cellular excitability and contribute to pain, somatosensation, anesthesia, and mood. Despite their physiological importance, K_2Ps lack specific pharmacology. Addressing this issue has been complicated by the challenges that the leak nature of K_2P currents poses for electrophysiology-based high-throughput screening strategies. Here, we present a yeast-based high-throughput screening assay that avoids this problem. Using a simple growth-based functional readout, we screened a library of 106,281 small molecules and identified two new inhibitors and three new activators of the mammalian K_2P channel K_2P2.1 (KCNK2, TREK-1). By combining biophysical, structure–activity, and mechanistic analysis, we developed a dihydroacridine analogue, ML67-33, that acts as a low micromolar, selective activator of temperature- and mechano-sensitive K_2P channels. Biophysical studies show that ML67-33 reversibly increases channel currents by activating the extracellular selectivity filter-based C-type gate that forms the core gating apparatus on which a variety of diverse modulatory inputs converge. The new K_2P modulators presented here, together with the yeast-based assay, should enable both mechanistic and physiological studies of K_2P activity and facilitate the discovery and development of other K_2P small molecule modulators.

The expression of multiple ion channels and receptors is essential for nociceptors to detect noxious stimuli of a thermal, mechanical or chemical nature. The peripheral sensory transduction systems of the urinary bladder include sensory nerve endings, urothelial cells and others whose location is suitable for transducing mechanical and chemical stimuli. There is an increasing body of evidence implicating the Deg/ENaC and TRP channel families in the control of bladder afferent excitability under physiological and pathological conditions. Pharmacological interventions targeting these ion channels may provide a new strategy for the treatment of pathological bladder sensation and pain.

• ion channel
• nociception
• sensation
• transient receptor potential
• urinary bladder

• Adrenergic alpha-1 Receptor Antagonists
• Adrenergic beta-Agonists/therapeutic use
• Adrenergic beta-Antagonists/therapeutic use
• Botulinum Toxins, Type A/therapeutic use
• Capsaicin/therapeutic use
• Humans
• Muscarinic Antagonists/therapeutic use
• Potassium Channels/drug effects
• TRPV Cation Channels/agonists
• Tachykinins/therapeutic use
• Treatment Outcome
• Urinary Bladder/drug effects
• Urinary Bladder/innervation
• Urinary Bladder/physiopathology
• Urinary Bladder, Neurogenic/drug therapy
• Urinary Bladder, Neurogenic/physiopathology
• Urinary Bladder, Overactive/drug therapy
• Urinary Bladder, Overactive/physiopathology

• Animals
• Cell Line
• Hydrogen-Ion Concentration
• Male
• Membrane Potentials
• Muscle, Smooth, Vascular/physiology
• Potassium Channels/physiology
• Potassium Channels, Tandem Pore Domain/antagonists & inhibitors
• Potassium Channels, Tandem Pore Domain/genetics
• Potassium Channels, Tandem Pore Domain/physiology
• Pulmonary Artery/physiology
• RNA Interference
• RNA, Small Interfering/pharmacology
• Rats
• Rats, Sprague-Dawley