Roles of endothelium and potassium channel blockers on CSA-induced relaxation.

<p>Relaxation effect of CSA in renal arteries from male and female rats (A), after 30 min-pretreatment of 10 µM ICI182780 (B), with or without endothelium (C), after 30 min-pretreatment of 100 µM L-NAME or 10 µM indomethacin (D), 10 µM BaCl₂ or 10 µM glibenclamide (E), and 3 mM TEA⁺, 1 mM 4-AP or 1 µM propranolol (F). Values are means ± S.E.M of 6 experiments.</p

Involvement of calcium channels in CSA-induced relaxation.

<p>Representative traces (A) and summarized graph (B) showing CaCl₂-induced dose-dependent contraction in the absence and presence of different concentration of CSA in rings without endothelium. CSA-induced relaxation in endothelium-denuded rings contracted by 30 nM (−)-Bay K8644 in 15 mM KCl solution (C and D). Values are means ± S.E.M of 6 experiments. *P<0.05 compared with control or vehicle control.</p

Effect of CSA on phosphorylation of MLC, MYPT1, and PKC.

<p>Effect of 10 µM CSA on (A and B) U46619- or (C, D and E) PMA-induced phosphorylation of MLC at Ser19 (p-MLC), MYPT1 at Thr853 (p-MYPT1) and PKCδ at Thr505 (p-PKCδ) as compared to their total levels (t-MLC, t-MYPT1 and t-PKCδ). The lower bands in the t-MYPT1 blot in (B) were unknown proteins probably non-specifically probed by the primary antibodies. Values are means ± S.E.M of 8 experiments. *P<0.05 compared with control and #p<0.05 compared with U46619 or PMA.</p

Responses to CSA in different constrictors.

<p>The pD₂ values and maximum response E_max (%) for CSA-induced relaxation in rat renal arteries contracted by different constrictors. Values are means ± S.E.M of n experiments, n = 5−6. *P<0.05 compared with vehicle control.</p

Effect of CSA on Ca²⁺ influx in smooth muscle tissue of renal arteries.

<p>Representative images (A) and summarized graph (B) showing the changes of intracellular Ca²⁺ concentration upon stimulation of 60 mM KCl after pre-incubation of 10 µM CSA or 100 nM nifedipine for 30 min. Values are means ± S.E.M of 4 experiments. *P<0.05 compared with control.</p

Effect of CSA on agonists-induced contraction.

<p>Concentration-response curves for CSA-induced relaxation in rat renal arteries contracted by 60 mM KCl (A), 0.5 µM phenylephrine (Phe) (B), 1 µM Serotonin (C) and 100 nM U46619 (D). Each value represents the mean ± S.E.M of 5–6 independent experiments. *P<0.05 compared with vehicle control.</p

Chemical Structure of cajaninstilbene acid (CSA).

<p>The chemical structure of CSA.</p