Fig. 1. Effects of left perisciatic injection of 0.1 ml of: tetrodotoxin (TTX) 60 μM (  A ), tetrodotoxin 60 μM plus epinephrine 55 μM (1:100,000) (  B ), or saline (  C ) on blood flow in perisciatic muscle and tetrodotoxin 60 μM (  D ), tetrodotoxin 60 μM plus epinephrine 55 μM (1:100,000) (  E ), or saline (  F ) in sciatic nerve. The plots show blood flows in left (drug-injection, •) and right (contralateral control, ○) tissues. Compared with baseline, tetrodotoxin significantly increased perisciatic muscle blood flow bilaterally (  A ), but the increases in flow were significantly greater on the ipsilateral (left) side compared with contralateral side at 5 min postinjection. Coinjection of epinephrine with tetrodotoxin prevented tetrodotoxin-induced increase in bilateral perisciatic muscle blood flow (  B ). Saline injection produced no changes in perisciatic muscle blood flow (  C ). Neither tetrodotoxin alone (  D ), tetrodotoxin coinjected with epinephrine (  E ), nor saline control (  F ) altered sciatic nerve blood flow significantly at any time point. n = 6 animals for each condition. Data are expressed as mean ± SD. *P < 0.05 comparing same-site measurements at that time point  versus measurements at time 0 (preinjection). †  P < 0.05 comparing between-site (ipsilateral  versus contralateral control) at the same time point.