FIGURE 4.

Tetrahydropalmatine inhibited intracellular Ca²⁺ release-induced vascular contraction. (A) Pre-treatment THP (10, 30, and 100 μM) suppressed KCl (60 mM) induced contraction of aorta in Ca²⁺-free Krebs solution. (B) Pre-treatment THP (10, 30, and 100 μM) suppressed Phe (1 μM) induced vascular contraction of aorta in Ca²⁺-free Krebs solution. (C) Pre-incubation Ryr inhibitor ruthenium red (RR, 10 μM) or IP3 receptor inhibitor heparin (5 mg/ml) attenuated THP induced rat aorta relaxation in Phe (1 μM) induced vascular tension in Ca²⁺-free Krebs solution. Vascular contraction and relaxation presented as percentage of control or evoked tone. Results were means ± SEM of more than three experiments. ^∗∗P < 0.01, ^∗∗∗P < 0.001 versus control group.