Figure 9. The effects activators and inhibitors of protein kinase C (PKC) on the rate of transepithelial fluid secretion in isolated Malpighian tubules of Aedes aegypti. In view of the variability in spontaneous (control) rates of fluid secretion in Malpighian tubules from different hatches of mosquitoes, each tubule was used as its own control. Accordingly, the paired student t‑test was used to evaluate the significance of the difference between the control and experimental periods. (A) Aedeskinin‑III (AK = III, 10−6 M) significantly increases the rate of fluid secretion. Data are from Schepel et al.72 (B) The PKC activator phorbol myristate acetate (PMA, 10−6 M) significantly reduced transepithelial fluid secretion. (C) The PKC inhibitor bisindolylmaleimide‑I (BIM‑I, 10−5 M) significantly reduced transepithelial fluid secretion. (D) The PKC inhibitor BIM‑I blocked the diuretic effects of aedeskinin‑III (AK‑III). Data are mean ± SE; (n = number of Malpighian tubules tubules); *, p < 0.05; **, p < 0.02; ***, p < 0.001; ns, not significant.