Fig. 2. Effect of pentobarbital on vasopressin-induced accumulation of HSP27 in A10 cells. (A ) Time course of the accumulation of HSP27 during the incubation period after vasopressin stimulation. Cultured cells were pretreated with 0.4 mm pentobarbital (closed symbols) or vehicle (open symbols) for 20 min, then exposed to 0.1 μm of vasopressin (circles) or vehicle (triangles) for the indicated periods. (B ) Dose-dependent effect of pentobarbital on the accumulation of HSP27. Cultured cells were pretreated with various doses of pentobarbital for 20 min, then exposed to 0.1 μm vasopressin (closed circles) or vehicle (open circles) for 48 h. The concentrations of HSP27 in cell extracts were determined by a specific immunoassay. Each value represents the mean ± SD of triplicate determinations. Similar results were obtained with two other cell preparations. *P < 0.05 compared with vasopressin alone.