Fig. 7. Effects of “acute” application of halothane or nifedipine on vascular smooth muscle precontracted with high K+physiologic saline solution (1.6 mm extracellular [Ca2+] concentration) are shown. (A ) Raw data traces demonstrate that halothane, 4.5%, and 1 μm nifedipine have comparable effects on contraction (upper panel ), but the effects on intracellular [Ca2+] concentration ([Ca2+]i) differ considerably (lower panel ). The concentration-dependent inhibitory effects of halothane (0.5–4.5%) or 1 μm nifedipine on (B ) contraction and (C ) [Ca2+]iare shown using this protocol. The contrasting effects of nifedipine on [Ca2+]isignaling and the Ca2+desensitizing effect of halothane are again evident using this protocol. Mean data from five vessels are shown (± SD). *P < 0.05, **P < 0.01 versus corresponding control values.