Fig. 6. Influence of A23178 on halothane-induced biphasic effects on pCa-induced force. A23178 = Ca2+ionophore to deplete Ca2+from the SR; 0/0 = without halothane or A23187; 3% halothane was present in 0 and 10 μm A23187; mean ± SD (n = 4–10); pCa-induced force after administration of halothane at peak force or 15 min expressed as percent of the control force (steady state force before the administration of halothane); *=P < 0.05 compared to no halothane or A23187 (0/0); #= compared to halothane in the absence of A23187 (0). Halothane-increased force was completely blocked by A2318 (peak contraction), and the decreased force was enhanced by A23187 (late relaxation).