Figure 7. The association between GABA_B receptors, N‐type calcium channels, and the BK channel .

A, an outward current was elicited by a step from −70 to +10 mV (black trace). Baclofen (10 μm) reduced this outward current (green trace). After washout of the baclofen action, iberiotoxin (100 nm) produced a larger reduction of this outward current (blue trace) and occluded the effect of baclofen (purple trace). B, when internal calcium was buffered to approximately 3 μm and voltage‐gated calcium channels were blocked, then baclofen (10 μm) did not affect the outward current. C, in the same cell shown in A, omega conotoxin GVIA (3 μm) produced a reduction of outward current (red trace) and occluded the effect of baclofen (yellow trace). D, summary of the effects of iberiotoxin and omega conotoxin GVIA on the action of baclofen (n = 7). On average, 10 μm baclofen suppressed 15 ± 3% of the outward current, which was significantly less (P < 0.05) than the suppression produced by iberiotoxin or conotoxin. Iberiotoxin alone suppressed 25 ± 3% of the outward current, while with baclofen it suppressed 27 ± 2% of the current. Conotoxin alone suppressed 26 ± 2% of the outward current, while with baclofen it suppressed 24 ± 5%. The effects of iberiotoxin and conotoxin showed no statistically significant difference alone as compared to in the presence of baclofen.