Fig. (3) Tianma enhanced ACh-induced vasorelaxation in endothelium-intact rat thoracic arterial rings (II). Analysis of ACh induced relaxations in PE (10^-6 M) pre-contracted isolated endothelium-intact arterial rings from control and tianma-treated rats. One-year-old rats were treated with or without tianma for three months at ~2.5g/kg/day and the thoracic aortas were isolated. The endothelium-intact arterial rings were first pre-contracted by PE (10^-6 M). Increasing concentrations of ACh were added and then the percentage of ACh-induced relaxation to PE (10^-6 M) contraction was measured as described in the materials and methods. Data points represent means ± SD of measurements in 8 arterial rings from 5 rats of each group (*P < 0.05 compared with the control group).