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: Rapidly inactivating and non-inactivating calcium-activated potassium currents in frog saccular hair cells

doi: 10.1111/j.1469-7793.2001.00049.x

Figure Lengend Snippet: Application of 100 nm IbTX eliminated both Itransient and Isteady in this hair cell (A), while in another hair cell 1 μm apamin had no effect (B). The right-hand panel in A shows the peak I–V relationship for this cell before (□) and during (•) IbTX application. The voltage protocol used to elicit these currents was the same as in Figs 2 and ​and6.6. The largest amplitude voltage reached (RS corrected) for each family of traces is indicated on the right. Recordings were made using the perforated-patch configuration and 10 mm 4-AP was present throughout. Note that the currents in A were elicited by 10 ms duration voltage steps while those in B are in response to 15 ms duration steps.

Article Snippet: Iberiotoxin (IbTX) was obtained from Bachem (King of Prussia, PA, USA) and apamin was obtained from Calbiochem (La Jolla, CA, USA).

Techniques: