Fig. 2.

Protein kinase A (PKA) inhibition abolishes the effects of Na₂S on increasing Ca²⁺ influx. The effects of the PKA inhibitor H-89 (A) or the protein kinase C (PKC) inhibitor bisindolylmaleimide I (BIS-1; B) on Na₂S-treated larval zebrafish are shown. In both experiments, fish were acclimated to low-[Ca²⁺] (25 μM) water beginning at 1 day postfertilization (dpf), and influx was performed in normal [Ca²⁺] (250 μM) water at 4 dpf. Values are means ± SE; N = 6. *Statistical difference between 0 and 10 μM Na₂S exposure. ^a,b,x,y Different letters represent a statistical difference between control and H-89/BIS-1 treatment within the same Na₂S exposure group (two-way ANOVA, followed by a Holm-Sidak post hoc test; P < 0.05).