Figure 2.

Tubeimoside I (TBMS1) may compete for a binding site with Yoda1 and the inhibitory effect is reversible. (A) Intracellular Ca²⁺ measurements with indicated concentrations of Yoda1 after cells were pretreated with 10 μM TBMS1. Error bars indicate SEM (N = 8 each). (B) The inhibition rate of TBMS1 with indicated concentrations of Yoda1 measured between 40–60 s after Yoda1 application, expressed as a percentage of the 1 μM Yoda1 response. Error bars indicate SEM (n = 5). *P < 0.05. (C) Intracellular Ca²⁺ responses of HUVECs to 5 μM Yoda1 after the cells were pretreated for 15 min with 10 μM TBMS1 (blue trace)/DMSO (grey trace). For the red trace, cells were pretreated for 15 min with 10 μM TBMS1, washed twice with SBS and then intracellular Ca²⁺ measurements were made 15 min after (N = 24 each). (D) Summary of the results presented in (C) expressed as a percentage of the cell response to Yoda1 after cells were pretreated with DMSO, TBMS1, or washed TBMS1 off. Error bars indicate SEM (n = 5). *P < 0.05.