Electrophysiology assays

G, Jiang H, Chen K. Structure-based discovery of potassium channel blockers from natural products virtual screening and electrophysiological assay testing. Chem Biol 2003 10 1103-13. 

For the electrophysiological assay, BCjHl cells that express the muscle-type nAChR are plated in cell culture dishes. 

Lubbert H, Hoffman BJ, Snutch TP, et al. cDNA cloning of a serotonin 5-HTlc receptor by electrophysiological assays of mRNA-injected Xenopus oocytes. Proc Natl Acad Sci USA 1987 84 4332-4336. 

Likewise, important issues remain with the automated patch clamp technology. There is no doubt that this approach has filled the niche between HT low information content assays, such as fluorescence and binding assays, and low throughput high quality content, such as conventional patch clamp electrophysiology assays. However, this technology comes at a tremendous price. At an approximate cost of US 400000 each, these systems are expensive... 

CF-subjects with mild or severe lung disease and CBAVD subjects with one or two CFTR mutations (Fig. 6). To measure mutant CFTR function in vivo, nasal potential difference (NPD) recording techniques are used. This in vivo electrophysiology assay measures ion transport across the nasal membrane of human subjects. CFTR activity is isolated by addition of Cl" free media and /J-adrcncrgic agonists to increase cAMP signaling. The non-CF subjects respond with a robust increase in wild-type CFTR activity. In contrast, the response in subjects with no, mild and severe lung disease was 68 9% (44-88%), 9 6% (0-33%), and <1% of that observed for wild-type CFTR, respectively (Fig. 6 Table 4). 

The inhibitory potencies of three of these molecules agreed with published values for murine Kv 3 (Table 4.1). The one exception was ShK that appeared to be 10-fold less potent than both published values and our own in-house values obtained by manual patch-clamp methods. It has been reported that ShK has a slow on-rate (t= 20 min) for block of Kv 3 (Middleton et al. 2003). This phenomenon may contribute to the reduced potency of ShK in our automated electrophysiology assay, because our protocol included a compound incubation time of only 5 to 10 min. Longer compound incubation times may improve the potency of ShK but would be associated with greater run-down in the K+ current amplitude. We also tested the A LI-selective blocker, dendrotoxin, and not surprisingly it did not inhibit the Kv. 3 current at concentrations up to 167 nM, which is well above its IC50 value for Kv 1.1 in our hands (17 pM data not shown). 

John, V.H. et al. 2007. Novel 384-well population patch-clamp electrophysiology assays for Ca2+-activated K+ channels. J. Biomol. Screen. 12, 50-60. 

Note 2 The authors of the reference protocol additionally compared the IC50 values obtained by the rubidium efflux assay, electrophysiology assay, and dofetilide displacement assay for astemizole, E-4031, cisapride, terfenadine, risperidone, quinidine, and sotalol, and the obtained values are demonstrated in Table 1. 

In order to further characterize nAChR subtype selectivity, (S)-6 was tested in an electrophysiological assay. 

Cdrdova, M., Fonseca, M., and Suarez-Isla, B.A. The detection firnit of the AOAC mouse bioassay for PSP toxins as determined by an electrophysiological assay. Biophys. J., 84, 1037-Pos, 2003. 

Suarez-lsla, B.A., Cordova, M., and Fonseca, M. RBA. Evaluation of new radiolabeled saxitoxins and intra-laboratory comparison with mouse bioassay and electrophysiological assay for PSP. Marine and Freshwater Toxins Analysis 1st Joint Symposium and AOAC Task Force Meeting Baiona, Spain, April 2005. 

Functional behavior training and electrophysiological assays for nerve repair... 

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