Fig. 2. Data traces showing typical responses in (A ) vessel inner diameter and (B ) intracellular Ca²⁺concentration ([Ca²⁺]ⁱ) during the stepwise increases in extracellular Ca²⁺concentration ([Ca²⁺]^o) in high K⁺(40 mm)–depolarized, endothelium-denuded mesenteric resistance arteries. Control responses are shown at the top, followed by responses during application of halothane (0.5–4.5%) or nifedipine (1 mm). Halothane and nifedipine additions were made to the bath 10 min before and then continuously throughout the stepwise increases in [Ca²⁺]^o. Five minutes was allowed for equilibration after each step increase in [Ca²⁺]^o.