Figure 1: Effect of betulinic acid (BA, 0.1– 100 μM) on vasorelaxation of endothelium-intact (+E) and -denuded (-E) aortic rings p reviously contracted by 1 μM phenylephrine (PE). Tension was measured and calculated as a percentage of the contraction elicited by PE. All data are expressed as mean ± SD; n = 7 rings from the seven rats per group. **P < 0.01 vs. Con