Figure 7. Comparison of thermal latency in the left leg resulting from subcutaneous drug injections at the nuchal midline. Thirty-five nanomoles per kilogram (11.4 [micro sign]g/kg) tetrodotoxin was injected alone (open squares) or coinjected in 15.4 mM (0.5%) bupivacaine (dark circles), or with bupivacaine injected simultaneously at a separate site (dark triangles). Thermal latency is increased when bupivacaine is not coinjected with tetrodotoxin. Coinjection of 55 [micro sign]M (1:100,000) epinephrine has a similar effect on the latency time course of tetrodotoxin (dark squares). Mean +/- SD; n = 6 for all groups.