OBJECTIVETo investigate whether the methanol extract of Berberis amurensis Rupr. (BAR) augments penile erection using in vitro and in vivo experiments.

METHODSThe ex vivo study used corpus cavernosum strips prepared from adult male New Zealand White rabbits. In in vivo studies for intracavernous pressure (ICP), blood pressure, mean arterial pressure (MAP), and increase of peak ICP were continuously monitored during electrical stimulation of Sprague-Dawley rats.

RESULTSPreconstricted with phenylephrine (PE) in isolated endotheliumintact rabbit corus cavernosum, BAR relaxed penile smooth muscle in a dose-dependent manner, which was inhibited by pretreatment with NG-nitro-L-arginine methyl ester (L-NAME), a nitric oxide synthase inhibitor, and H-[1,2,4]-oxadiazole-[4,3-α]-quinoxalin-1-one, a soluble guanylyl cclase inhibitor. BAR significantly relaxed penile smooth muscles dose-dependently in ex vivo, and this was inhibited by pretreatment with L-NAME H-[1,2,4]-oxadiazole-[4,3-α]-quinoxalin-1-one. BAR-induced relaxation was significantly attenuated by pretreatment with tetraethylammonium (TEA, P<0.01), a nonselective K channel blocker, 4-aminopyridine (4-AP, P<0.01), a voltage-dependent K channel blocker, and charybdotoxin (P<0.01), a large and intermediate conductance Ca sensitive-K channel blocker, respectively. BAR induced an increase in peak ICP, ICP/MAP ratio and area under the curve dose dependently.

CONCLUSIONBAR augments penile erection via the nitric oxide/cyclic guanosine monophosphate system and Ca sensitive-K (BK and IK) channels in the corpus cavernosum.

Animals ; Area Under Curve ; Berberis ; chemistry ; Blood Pressure ; drug effects ; Cyclic GMP ; metabolism ; Epoprostenol ; pharmacology ; In Vitro Techniques ; Indomethacin ; pharmacology ; Male ; Models, Biological ; Muscle Relaxation ; drug effects ; Muscle, Smooth ; drug effects ; physiology ; NG-Nitroarginine Methyl Ester ; pharmacology ; Nitric Oxide ; metabolism ; Penile Erection ; drug effects ; Phenylephrine ; pharmacology ; Plant Extracts ; pharmacology ; Potassium Channel Blockers ; pharmacology ; Potassium Channels ; metabolism ; Pressure ; Rabbits

ATP-sensitive potassium channels (K) are energy sensors on the plasma membrane. By sensing the intracellular ADP/ATP ratio of β-cells, pancreatic K channels control insulin release and regulate metabolism at the whole body level. They are implicated in many metabolic disorders and diseases and are therefore important drug targets. Here, we present three structures of pancreatic K channels solved by cryo-electron microscopy (cryo-EM), at resolutions ranging from 4.1 to 4.5 Å. These structures depict the binding site of the antidiabetic drug glibenclamide, indicate how Kir6.2 (inward-rectifying potassium channel 6.2) N-terminus participates in the coupling between the peripheral SUR1 (sulfonylurea receptor 1) subunit and the central Kir6.2 channel, reveal the binding mode of activating nucleotides, and suggest the mechanism of how Mg-ADP binding on nucleotide binding domains (NBDs) drives a conformational change of the SUR1 subunit.
Adenosine Triphosphate ; metabolism ; Amino Acid Sequence ; Animals ; Binding Sites ; Cryoelectron Microscopy ; Ligands ; Mesocricetus ; Mice ; Models, Molecular ; Nucleotides ; metabolism ; Pancreas ; metabolism ; Potassium Channels, Inwardly Rectifying ; chemistry ; metabolism ; Protein Binding ; Protein Multimerization ; Protein Structure, Quaternary ; Protein Subunits ; chemistry ; metabolism ; Sf9 Cells ; Spodoptera ; Sulfonylurea Receptors ; chemistry ; metabolism

This study was aimed to establish a method to create a stable planar lipid bilayer membranes (PLBMs), in which large conductance calcium-activated potassium channels (BK) were reconstituted. Using spreading method, PLBMs were prepared by decane lipid fluid consisting of N-weathered mixture of phosphatidylcholine and cholesterol at 3:1 ratio. After successful incorporation of BKchannel into PLBMs, single channel characteristics of BKwere studied by patch clamp method. The results showed that i) the single channel conductance of BKwas (206.8 ± 16.9) pS; ii) the activities of BKchannel were voltage dependent; iii) in the bath solution without Ca, there was almost no BKchannel activities regardless of under hyperpolarization or repolarization conditions; iv) under the condition of +40 mV membrane potential, BKchannels were activated in a Caconcentration dependent manner; v) when [Ca] was increased from 1 μmol/L to 100 μmol/L, both the channel open probability and the average open time were increased, and the average close time was decreased from (32.2 ± 2.8) ms to (2.1 ± 1.8) ms; vi) the reverse potential of the reconstituted BKwas -30 mV when [K] was at 40/140 mmol/L (Cis/Trans). These results suggest that the spreading method could serve as a new method for preparing PLBMs and the reconstituted BKinto PLBMs showed similar electrophysiological characteristics to natural BKchannels, so the PLBMs with incorporated BKcan be used in the studies of pharmacology and dynamics of BKchannel.
Animals ; Calcium ; chemistry ; Electrophysiological Phenomena ; Large-Conductance Calcium-Activated Potassium Channels ; chemistry ; Lipid Bilayers ; chemistry ; Membrane Potentials ; Patch-Clamp Techniques

To explore whether hypoxic condition could promote the olfactory mucosa mesenchymal stem cells (OM-MSCs) to differentiate into neurons with the olfactory ensheathing cells (OECs) supernatant and the potential mechanisms.
 Methods: The OM-MSCs and OECs were isolated and cultured, and they were identified by flow cytometry and immunofluorescence. The OM-MSCs were divided into three groups: a 3%O2+ HIF-1α inhibitors (lificiguat: YC-1) + OECs supernatant group (Group A) , a 3%O2 + OECs supernatant group (Group B) and a 21%O2 + OECs supernatant group (Control group). The neurons, which were differentiated from OM-MSCs, were assessed by immunofluorescence test. The mRNA and protein expression of hypoxia-inducible factor-1α (HIF-1α), βIII-tubulin and glial fibrillary acidic portein (GFAP) were detected by quantitative polymerase chain reaction (Q-PCR) and Western blot. The potassium channels were analyzed by patch clamp.
 Results: The neurons differentiated from OM-MSCs expressed the most amount of βIII-tubulin, and the result of Q-PCR showed that HIF-1α expression in the Group B was significantly higher than that in the other groups (all P<0.05). Western blot result showed that the βIII-tubulin protein expression was significantly higher and GFAP protein expression was obviously decreased in the Group B (both P<0.05). The patch clamp test confirmed that the potassium channels in the neurons were activated.
 Conclusion: Hypoxic condition can significantly increase the neuronal differentiation of OM-MSCs by the OECs supernatant and decrease the production of neuroglia cells, which is associated with the activation of HIF-1 signal pathway.
Blotting, Western ; Cell Differentiation ; physiology ; Cells, Cultured ; Culture Media, Conditioned ; chemistry ; pharmacology ; Flow Cytometry ; Glial Fibrillary Acidic Protein ; metabolism ; Hypoxia ; physiopathology ; Hypoxia-Inducible Factor 1, alpha Subunit ; metabolism ; Indazoles ; pharmacology ; Mesenchymal Stem Cells ; physiology ; Neurogenesis ; physiology ; Neuroglia ; metabolism ; physiology ; Neurons ; physiology ; Olfactory Mucosa ; Potassium Channels ; Signal Transduction ; Tubulin ; metabolism

Small conductance Ca(2+)-activated potassium channels (SK channels) distributing in the nervous system play an important role in learning, memory and synaptic plasticity. Most pharmacological properties of them are determined by short-chain scorpion toxins. Different from most voltage-gated potassium channels and large-conductance Ca(2+)-activated potassium channels, SK channels are only inhibited by a small quantity of scorpion toxins. Recently, a novel peptide screener in the extracellular pore entryway of SK channels was considered as the structural basis of toxin selective recognition. In this review, we summarized the unique interactions between scorpion toxins and SK channels, which is crucial not only in deep-researching for physiological function of SK channels, but also in developing drugs for SK channel-related diseases.
Animals ; Memory ; Neuronal Plasticity ; Scorpion Venoms ; chemistry ; Scorpions ; Small-Conductance Calcium-Activated Potassium Channels ; antagonists & inhibitors

Voltage-gated potassium channels (Kv4.1, Kv4.2 and Kv4.3) encoded by the members of the KCND/Kv4 (Shal) channel family mediate the native, fast inactivating (A-type) K(+) current (IA) described both in heart and neurons. This IA current is specifically blocked by short scorpion toxins that belong to the α-KTx15 subfamily and which act as pore blockers, a different mode of action by comparison to spider toxins known as gating modifiers. This review summarizes our present chemical and pharmacological knowledge on the α-KTx15 toxins.
Animals ; Potassium Channel Blockers ; chemistry ; Scorpion Venoms ; chemistry ; Scorpions ; Shal Potassium Channels ; antagonists & inhibitors

The large-conductance calcium-activated potassium (BK) channels distributed in both excitable and non-excitable cells are key participants in a variety of physiological functions. By employing numerous high-affinity natural toxins originated from scorpion venoms the pharmacological and structural characteristics of these channels tend to be approached. A 37-residue short-chain peptide, named as martentoxin, arising from the venom of the East-Asian scorpion (Buthus martensi Karsch) has been investigated with a comparatively higher preference for BK channels over other voltage-gated potassium (Kv) channels. Up to now, since the specific drug tool probing for clarifying structure-function of BK channel subtypes and related pathology remain scarce, it is of importance to illuminate the underlying mechanism of molecular interaction between martentoxin and BK channels. As for it, the current review will address the recent progress on the studies of pharmacological characterizations and molecular determinants of martentoxin targeting on BK channels.
Amino Acid Sequence ; Humans ; Large-Conductance Calcium-Activated Potassium Channels ; antagonists & inhibitors ; Ligands ; Peptides ; chemistry ; Scorpion Venoms ; chemistry

Large-conductance Ca²⁺-activated K⁺ channels (BK channels) constitute an key physiological link between cellular Ca²⁺ signaling and electrical signaling at the plasma membrane. Thus these channels are critical to the control of action potential firing and neurotransmitter release in several types of neurons, as well as the dynamic control of smooth muscle tone in resistance arteries, airway, and bladder. Recent advances in our understanding of K⁺ channel structure and function have led to new insight toward the molecular mechanisms of opening and closing (gating) of these channels. Here we will focus on mechanisms of BK channel gating by Ca²⁺, transmembrane voltage, and auxiliary subunit proteins.
Animals ; Calcium Signaling ; Cytoplasm ; metabolism ; Electric Conductivity ; Electrophysiological Phenomena ; Humans ; Ion Channel Gating ; Large-Conductance Calcium-Activated Potassium Channels ; chemistry ; metabolism ; Protein Subunits ; chemistry ; metabolism

OBJECTIVETo study the chemical constituents of Iodes cirrhosa and evaluate their bioactivity.

METHODThe compounds were isolated and purified by various kinds of column chromatography methods and their structures were determined by spectroscopic data analysis. Neuroprotective assay against serum deprivation induced SH-SYSY-JNK3 cell apoptosis was evaluated by MTr method while potassium channel-blocking activity was assayed in both non-specific and specific K+ channel-regulator screening models.

RESULTTwenty-one compounds were obtained from an EtOAc portion of an ethanolic extract of the root of I. cirrhosa. Their structures were elucidated as 1beta, 3beta-dihydroxyurs-9(11),12-diene(1), bauerenyl acetate(2),3beta-hydroxy-11-oxo-olean-12-enyl palmitate(3), 3beta-acetoxy-urs-12-ene-11-one(4), betulinic acid(5), stigmasta-5, 22-diene-3beta-ol(6), 7beta-hydroxystigmasterol(7), stigmasta-5, 22diene-3beta-ol3-O-beta-D-glucopyranoside(8),scopoletin(9),scopolin(10),clovamide(11),methyl 3,5-di-O-caffeoylquinate(12),3,5-dicaffeoylquinic acid(13),2,6-dimethoxy-1,4-benzoquinone(14), protocatechualdehyde(15), vanillin(16), protocatechuic acid(17), vanillic acid(18),caffeic acid(19),azelaic acid(20),and succinic acid(21). Compound 3,4,6,9,10,14,15,18 and 20 showed neuroprotective activities against serum deprivation induced SH-SYSY-JNK3 cell apoptosis at a concentration of 1.0 x 10(6) mol x L(1) with relative protection rates of 177%, 144%, 137%, 137%, 143%, 145%, 137%, 189%, 130%, respectivley. Compound 16 could increase DiBAC4(3) fluorescence response in both non-specific and specific K+ channel-regulator screening models at the concentration of 1.0 x 10(-5) mol x L(-1).

CONCLUSIONCompound 1 was a new compound and all compounds were isolated from this genus for the first time. Compounds 3,4,6,9,10,14,15,18 and 20 showed neuroprotective activities while 16 exhibited K+ channel-blocking activity.

Apoptosis ; drug effects ; Cell Line, Tumor ; Humans ; Magnoliopsida ; chemistry ; Neuroprotective Agents ; chemistry ; pharmacology ; Plant Extracts ; chemistry ; pharmacology ; Potassium Channels ; drug effects

Due to the complicated pathogenesis of cardiac arrhythmia, the safe and effective therapeutic strategies for cardiac arrhythmia remain an urgent medical problems in the recent years. In this paper, we introduced the research practice of anti-arrhythmic agents targeting on potassium ion channel. The research progress of anti-arrhythmic agents in up-to-date literatures were also reviewed and prospected.
Amiodarone ; analogs & derivatives ; chemistry ; pharmacology ; therapeutic use ; Animals ; Anti-Arrhythmia Agents ; chemistry ; pharmacology ; therapeutic use ; Arrhythmias, Cardiac ; drug therapy ; physiopathology ; Humans ; Hydantoins ; Imidazolidines ; chemistry ; pharmacology ; therapeutic use ; Molecular Structure ; Piperazines ; chemistry ; pharmacology ; therapeutic use ; Potassium Channel Blockers ; pharmacology ; therapeutic use ; Potassium Channels ; drug effects