Figure 5. Potassium-evoked oscillations without action potential dependent chemical neurotransmission in the rat substantia gelatinosa in vitro and the involvement of gap junction coupling.

A, example traces from the same experiment showing potassium-induced oscillations before (left panel) and after bath application of calcium-free perfusate either alone (middle panel) or in subsequent combination for 45 min with the gap junction blocker 1 mm octanol (right panel). B, calcium-free perfusate caused a reduction in the peak amplitude of the power spectrum (middle panel). There was a further reduction in peak amplitude on subsequent addition of octanol to the calcium-free perfusate (right panel). C, autocorrelograms showing that frequency of the oscillation was unchanged. D, quantified data (n = 6) showing that the peak power and area power are significantly reduced (P < 0.05) by the calcium-free perfusate (left panel). A combination of calcium-free perfusate and octanol caused a further significant reduction in the peak power and area (left panel). Neither the calcium-free perfusate alone or in combination with octanol had any significant effect (P > 0.05) on the frequency of the oscillation (right panel). *P < 0.05 paired t test versus calcium-free perfusate.