Journal: eLife

Article Title: Biophysical K v 3 channel alterations dampen excitability of cortical PV interneurons and contribute to network hyperexcitability in early Alzheimer’s

doi: 10.7554/eLife.75316

Figure Lengend Snippet:

Article Snippet: Chemical compound, drug , Iberiotoxin (IBTX) , Alamone Labs , Cat# STI-400 , Drug used to block BK channels.

Techniques: Recombinant, Construct, Blocking Assay, Software

Journal: Frontiers in Physiology

Article Title: TRPV4 Complexes With the Na + /Ca 2+ Exchanger and IP 3 Receptor 1 to Regulate Local Intracellular Calcium and Tracheal Tension in Mice

doi: 10.3389/fphys.2019.01471

Figure Lengend Snippet: Effects of Ca 2+ -activated K + channel inhibitors on tracheal rings precontracted with a TRPV4 activator. Compared with that in the control groups, the carbachol precontracted-tracheal ring relaxation-induced by GSK1016790A was not significantly reduced by pretreatment with the large-, intermediate-, and small-conductance Ca 2+ -activated K + channel inhibitors IbTX (50 μM), TRAM34 (10 μM), and apamin (1 μM). Data are shown as means ± SE; n = 5 mice.

Article Snippet: Iberiotoxin (IbTX), and TRAM34 were purchased from MedChemExpress.

Techniques: Control

Journal: The Journal of Neuroscience

Article Title: Phenotypic Alteration of a Human BK ( hSlo ) Channel by hSloβ Subunit Coexpression: Changes in Blocker Sensitivity, Activation/Relaxation and Inactivation Kinetics, and Protein Kinase A Modulation

doi: 10.1523/JNEUROSCI.16-15-04543.1996

Figure Lengend Snippet: Slow current inactivation reduction in oocytes expressing hSlo + hSloβ relative to those expressing hSlo. A, In a paired-pulse paradigm, to examine the rate of recovery from inactivation, a 1 sec voltage step (−60 mV hold to 100 mV) was used as the “conditioning” stimulus to produce a significant level of inactivation (time 0, end of the conditioning pulse), followed at an increasing interval by a single identical “test” voltage step. Initial inactivation was measured by comparing the early peak current of the conditioning voltage step with the residual current at the end of the first step. Peak current amplitudes of the subsequent step in each paired episode were used to measure recovery. The conditioning step produced significantly greater levels of inactivation of hSlo currents compared with expressing hSlo + hSloβ currents (ttest; p < 0.001), and recovery was significantly slower (repeated measures ANOVA, F = 15.9, p = 0.005). Full recovery was not achieved by 7.5 sec after the conditioning pulse. With longer single voltage steps (10 sec), a significant increase in the time course of inactivation was observed (hSlo τ1 = 309.7 ± 36.2 msec, n = 5; hSlo + hSloβ τ1 = 702.0 ± 88.2 msec, n = 5; p = 0.003, two-tailed t test; τ2 values not reported because of contamination by slowly activating native current). B, Examples of current inactivation and its recovery resulting from the paired-pulse paradigm (8 sweeps) in oocytes expressing hSlo or hSlo + hSloβ. The level of inactivation was independent of current amplitude (expression level) within the normal limits encountered in this study. There was no inactivation of native Ca2+-activated Cl−current, and currents represent IbTX-sensitive current components, after subtraction of residual currents in supramaximal IbTX.

Article Snippet: Iberiotoxin (IbTX) and charybdotoxin (ChTX) (Peptides International, Louisville, KY) were prepared as aqueous stocks and diluted in MBS before use; tetrandrine (Aldrich, Milwaukee, WI) was prepared as a stock solution in dimethylformamide or dimethylsulfoxide (DMSO) and likewise diluted in the appropriate solution just before use.

Techniques: Expressing, Produced, Two Tailed Test

Journal: The Journal of Neuroscience

Article Title: Phenotypic Alteration of a Human BK ( hSlo ) Channel by hSloβ Subunit Coexpression: Changes in Blocker Sensitivity, Activation/Relaxation and Inactivation Kinetics, and Protein Kinase A Modulation

doi: 10.1523/JNEUROSCI.16-15-04543.1996

Figure Lengend Snippet: IBTX and ChTX pharmacology. A, Application of the BK channel-blocking peptide IbTX to oocytes expressing hSlo or hSlo + hSloβ revealed that coexpression with the hSloβ subunit resulted in a nearly 10-fold decrease in the sensitivity to IbTX blockade;n = 5–10 oocytes/IbTX concentration. Maximal effect was defined as the effect produced by incubation in 100–250 nm IbTX; maximal levels of suppression did not differ significantly between hSlo and hSlo + hSloβ. B, Application of the peptidyl blocker ChTX did not reveal a significantly different profile of blockade forhSlo and hSlo + hSloβ. Maximal effect was defined as the response to 250–500 nmChTX, and maximal levels of effect did not differ betweenhSlo and hSlo + hSloβ.

Article Snippet: Iberiotoxin (IbTX) and charybdotoxin (ChTX) (Peptides International, Louisville, KY) were prepared as aqueous stocks and diluted in MBS before use; tetrandrine (Aldrich, Milwaukee, WI) was prepared as a stock solution in dimethylformamide or dimethylsulfoxide (DMSO) and likewise diluted in the appropriate solution just before use.

Techniques: Blocking Assay, Expressing, Concentration Assay, Produced, Incubation

Journal: International Journal of Molecular Sciences

Article Title: Theophylline-Induced Relaxation Is Enhanced after Testosterone Treatment via Increased K V 1.2 and K V 1.5 Protein Expression in Guinea Pig Tracheal Smooth Muscle

doi: 10.3390/ijms24065884

Figure Lengend Snippet: Voltage-dependent delayed rectifier K + (K V ) channels are involved in the theophylline-induced IK + enhancement after testosterone (TES) chronic incubation in guinea pig tracheal smooth muscle cells. ( A ) Perfusion of theophylline (Theo) 320 μM to single myocytes resulted in a significant increase in IK + from −40 mV ahead, which was partially reduced by 4-aminopyridine (4-AP, 3 mM), a blocker of K V channels. Subsequent administration of iberiotoxin (IBTX,100 nM), a specific blocker of BK Ca channels to the same cells, abolished the remaining theophylline-induced increase in IK + from 20 mV ahead ( n = 6). Calculation of the area under the curve (AUC) shows that K V channels are responsible for 72.17% of the theophylline response (light gray area), while BK Ca channels account for 27.83% (dark gray area). ( B ) The enhancement of theophylline-evoked increase of IK + by TES from −50 mV ahead, was almost blocked by 4-AP, suggesting a major role of K V channels in the androgen’s action, and the addition of IBTX nearly abolished the IK + ( n = 6). AUC analysis revealed that the contribution of K V and BK Ca channels to the TES-induced improved theophylline response was 82.37% (light gray area) and 17.62%, (dark gray area), respectively. These results reveal that the main K + channels involved in increasing the IK + triggered by theophylline are the K V channels and suggest that TES upregulates these proteins. Symbols depict the mean ± S.E.M. In panel ( A ), ** p < 0.01 when comparing Theo (o) vs. Control (●). † p < 0.05, †† p < 0.01, comparing Theo + 4-AP group (Δ) vs. Control group (●). ¶ p < 0.05, ¶¶ p < 0.01, comparing Theo + 4-AP + IBTX (□) vs. Control (●). In panel (B), ** p < 0.01 when comparing TES + Theo (o) vs. TES (●). † p < 0.05, †† p < 0.01, comparing TES + Theo + 4-AP (Δ) vs. TES (●). •• p < 0.01, comparing TES + Theo (o) vs. TES + Theo + 4-AP (Δ). ¶ p < 0.05, ¶¶ p < 0.01, comparing TES + Theo + 4-AP + IBTX (□) vs. TES (●). Repeated measure analyses of variance were performed, followed by Student–Newman–Keuls’ multiple comparison tests.

Article Snippet: Notably, 4-Aminopyridine (4-AP) was purchased from Research Chemical LTD (Word Hill, MA, USA), and iberiotoxin was acquired from Santa Cruz Biotechnology (Dallas, TX, USA).

Techniques: Incubation, Control, Comparison

Journal: International Journal of Molecular Sciences

Article Title: Theophylline-Induced Relaxation Is Enhanced after Testosterone Treatment via Increased K V 1.2 and K V 1.5 Protein Expression in Guinea Pig Tracheal Smooth Muscle

doi: 10.3390/ijms24065884

Figure Lengend Snippet: Administration of iberiotoxin followed by 4-aminopyridine shows the same pattern that voltage-gated delayed K + channels (KV) are the major contributors to the enhanced theophylline-induced K + currents after testosterone (TES) treatment. ( A ) Application of theophylline (Theo) 320 μM to single myocytes under control conditions (not incubated with TES) markedly increased the IK + from −50 mV ahead. This increase was slightly reduced by iberiotoxin (IBTX, 100 nM), a specific blocker of BK Ca channels. Successive administration of 4-aminopirydine (4-AP, 3 mM), a blocker of K V channels, to the same cells abolished the remaining Theo-induced increase of IK + from −40 mV ahead ( n = 6). BK Ca channels account for 35.17% of the theophylline response, according to an estimation of the area under the curve (AUC) (light gray region), while K V channels account for 64.83%. (dark gray area). ( B ) When myocytes were incubated with TES 40 nM, the addition of IBTX (100 nM) reduced the Theo-induced K + current by 31.8% (light gray area), whereas the addition of 4-AP (3 mM) eliminated the theophylline-triggered rise in IK + enhanced by TES, indicating a major role of K V channels (68.2%, dark gray area) in the androgen action ( n = 6). These results also suggest that TES upregulates these proteins. Symbols depict the mean ± S.E.M. In panel ( A ), ** p < 0.01 when comparing Control (●) vs. Theo (o) groups. †† p < 0.01, comparing Control (●) vs. Theo + IBTX (Δ). ¶ p < 0.05 comparing Control (●) vs. Theo + IBTX + 4-AP (□). In panel ( B ), ** p < 0.01 and * p < 0.05 when comparing TES (●) vs. TES + Theo (o) groups. † p < 0.05, †† p < 0.01, comparing TES (●) vs. TES + Theo + IBTX (Δ). •• p < 0.01, • p < 0.05, comparing TES + Theo (o) vs. TES + Theo + IBTX (Δ) groups. ¶ p < 0.05, ¶¶ p < 0.01, comparing TES (●) vs. TES + Theo + IBTX + 4-AP (□). Repeated measure analyses of variance were performed, followed by Student–Newman–Keuls’ multiple comparison tests.

Article Snippet: Notably, 4-Aminopyridine (4-AP) was purchased from Research Chemical LTD (Word Hill, MA, USA), and iberiotoxin was acquired from Santa Cruz Biotechnology (Dallas, TX, USA).

Techniques: Control, Incubation, Comparison

Journal:

Article Title: Propionate-induced relaxation in rat mesenteric arteries: a role for endothelium-derived hyperpolarising factor

doi: 10.1113/jphysiol.2001.013105

Figure Lengend Snippet: Modulation of propionate-induced relaxation

Article Snippet: Charybdotoxin, apamin, and iberiotoxin were from Bachem (St Helens, UK), and cyclopiazonic acid, thapsigargin, ouabain, indomethacin, acetylcholine, and N ω -nitro- l -arginine methyl ester ( l -NAME) were from Sigma.

Techniques:

Journal:

Article Title: Propionate-induced relaxation in rat mesenteric arteries: a role for endothelium-derived hyperpolarising factor

doi: 10.1113/jphysiol.2001.013105

Figure Lengend Snippet: A, mean (± s.e.m.) normalised contraction amplitude plotted at 1 min intervals, showing the effects of 100 nm iberiotoxin (IbTx) on responses to 10 mm propionate and paired time controls (n = 13). B, propionate-induced relaxations after correction for time controls, before and after treatment with IbTx.

Article Snippet: Charybdotoxin, apamin, and iberiotoxin were from Bachem (St Helens, UK), and cyclopiazonic acid, thapsigargin, ouabain, indomethacin, acetylcholine, and N ω -nitro- l -arginine methyl ester ( l -NAME) were from Sigma.

Techniques:

Journal: The Journal of Neuroscience

Article Title: Regulation of Nociceptive Glutamatergic Signaling by Presynaptic Kv3.4 Channels in the Rat Spinal Dorsal Horn

doi: 10.1523/JNEUROSCI.3212-17.2018

Figure Lengend Snippet: eEPSCs from superficial dorsal horn neurons are not affected by specific inhibitors of Kv7, BK, and Kv1 channels. A–C, Left and center, Consecutive monosynaptic eEPSCs recorded before and after (2–30 sweeps) exposing the spinal cord to the indicated K+ channel inhibitors (XE991, IbTX, and α-DTX). Averages are displayed in red. Right, Pooled paired measurements of peak EPSCs before (control) and after exposure to the indicated inhibitors. Sample size and p-values of the paired Student's t test are shown on the graphs. Stimulation parameters are as indicated in the legend to Figure 2 and in the Materials and Methods. Each symbol in the graphs represents an independent response from a separate spinal cord (i.e., the sample size corresponds to number of animals examined). Percentage change box plots are displayed to the right of summary data plots (legend to Fig. 5 describes box plot characteristics).

Article Snippet: Tetraethylammonium-Cl (TEA; Sigma-Aldrich), 4-aminopyridine (Sigma-Aldrich), α-dendrotoxin (α-DTX; Alomone Laboratories), iberiotoxin (IbTX; Smartox), and 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX disodium salt; Alomone Laboratories) were dissolved in deionized water and XE991 (Alomone) was dissolved in DMSO.

Techniques:

Journal: The Journal of Neuroscience

Article Title: Regulation of Nociceptive Glutamatergic Signaling by Presynaptic Kv3.4 Channels in the Rat Spinal Dorsal Horn

doi: 10.1523/JNEUROSCI.3212-17.2018

Figure Lengend Snippet: Submillimolar 4-aminopyridine and TEA consistently potentiate monosynaptic EPSCs. Pooled paired average peaks from the multipeak analysis (Fig. 7) before and after exposure to 50 μm 4-aminopyridine (A), 500 μm TEA (B), 100 nm IbTX (C), 30 μm XE991 (D), and 80 nm α-DTX (E). Color scheme displays the numerical order of peaks in a given recording (light gray = first peak, dark gray = second peak, light blue = third peak, dark blue = fourth peak, light pink = fifth peak, dark pink = sixth peak, averages shown in red). The p-values of the paired Student's t test are shown on the graphs. Percentage change box plots are displayed to the right of summary data plots (Fig. 5 legend describes box plot characteristics).

Article Snippet: Tetraethylammonium-Cl (TEA; Sigma-Aldrich), 4-aminopyridine (Sigma-Aldrich), α-dendrotoxin (α-DTX; Alomone Laboratories), iberiotoxin (IbTX; Smartox), and 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX disodium salt; Alomone Laboratories) were dissolved in deionized water and XE991 (Alomone) was dissolved in DMSO.

Techniques:

Journal: The Journal of Neuroscience

Article Title: Regulation of Nociceptive Glutamatergic Signaling by Presynaptic Kv3.4 Channels in the Rat Spinal Dorsal Horn

doi: 10.1523/JNEUROSCI.3212-17.2018

Figure Lengend Snippet: Analysis of primary nociceptor APs in the absence and presence of several K+ channel inhibitors. Left to right, Representative AP traces, phase plane plots, and changes in APD50, APD90, and maximum repolarization rate (derived from phase plane plots) before and after exposure to 50 μm 4-aminopyridine (A), 500 μm TEA (B), 100 nm IbTX (C), 30 μm XE991 (D), and 80 nm α-DTX (E). Averages are shown in black and p-values of the paired Student's t test are displayed on graphs. Additional properties are reported in Table 4.

Article Snippet: Tetraethylammonium-Cl (TEA; Sigma-Aldrich), 4-aminopyridine (Sigma-Aldrich), α-dendrotoxin (α-DTX; Alomone Laboratories), iberiotoxin (IbTX; Smartox), and 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX disodium salt; Alomone Laboratories) were dissolved in deionized water and XE991 (Alomone) was dissolved in DMSO.

Techniques: Derivative Assay