The solubilizing detergents, Tween 80 and Triton X-100 non-competitively inhibit α₇-nicotinic acetylcholine receptor function in Xenopus oocytes

Because many studies rely upon detergents to solubilize lipophilic agents such as cannabinoid drugs, we examined the effect of commonly employed detergents on the function of the cloned α₇ subunit of the nicotinic ACh receptor. Homomeric α₇ receptors were expressed in Xenopus oocytes and the two-microelectrode voltage-clamp technique was used to assess their electrophysiological properties. The detergents Tween 80 and Triton X-100 reversibly inhibited ACh (100 μM)-induced inward currents in a concentration-dependent manner, with IC₅₀ values of 610 nM and 1.4 μM, respectively. The effects of these detergents were independent of membrane potential, and they were not meditated by endogenous Ca ²⁺-dependent Cl^- channels, since they were unaffected by intracellularly injected BAPTA, and recorded in Ca²⁺-free bathing solution containing 2 mM Ba²⁺. Both detergents also decreased the maximal effect of ACh, without significantly affecting its EC₅₀, indicating a non-competitive interaction with the nACh α₇ receptors. In contrast to the effects of these detergents, we found that cholic acid (10 μM), DMSO (10 μM) and Tocrisol^® (0.01% v/v) did not cause a significant effect on nicotinic responses. In conclusion, we demonstrate that the detergents Tween 80 and Triton X-100 are potent inhibitors of neuronal nACh α₇ receptors expressed in Xenopus oocytes, and we suggest that studies utilizing these detergents to solubilize lipophilic drugs should be scrutinized for such effects.