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. 2008 Mar 3;154(1):216–225. doi: 10.1038/bjp.2008.73

Figure 1.

Figure 1

Gabapentin (GBP; 1-(aminomethyl) cyclohexaneacetic acid) activates renal outer medullary potassium (ROMK1) channels. All experiments are in FVPP solution at intracellular pH (pHi) 7.4. (a) The pulse protocol and current–voltage (I–V) curves for ROMK1 channels. ROMK1 channels were expressed in Xenopus oocytes and K+ currents (Ik) recorded using the inside-out giant patch-clamp method. Voltage pulses were applied from −100 mV to +100 mV in 25 mV increments. The holding potential was −60 mV. The ROMK1 channels showed a weak inwardly rectifying pattern. (b) Application of 0.1, 0.3 or 1 mM gabapentin significantly activates the ROMK1 current. (c) Application of 3 or 5 mM gabapentin significantly activates the ROMK1 current. (d) Activation of ROMK1 channels by gabapentin (0.1–5 mM) is concentration dependent (n=15); * indicates P<0.05 by ANOVA compared with the control. (e) Current–voltage (I–V) relationship in an inside-out patch before and after application of gabapentin (1 mM). (f) Concentration-dependent activation of ROMK1 channels by gabapentin. The activation of ROMK1 currents in the presence of different concentrations of gabapentin was fitted to the Hill equation, as described in the Methods. Gabapentin enhances ROMK1 channel activity with an EC50=313 μM.