Figure 5. Dose-response relation of various concentrations of halothane and caffeine-induced tension transients in skinned pulmonary arterial strips. Data are mean +/- SEM (n = 5–9) percent of control caffeine-induced tension transient. Halo-thane (0.5%-2.0%), in the uptake phase, decreased, and in the release phase, increased the caffeine-induced tension transients in a dose-dependent manner. (R)= halothane present in the caffeine-induced Ca2+ release phase;(U)= halothane present in the uptake phase.