Fig. 4.

Intracellular concentrations of guanidine compounds in human cells in HBSS buffer. Time course of intracellular concentration of (A) guanidine, (B) aminoguanidine, and (C) metformin in HEK-EV (●) and HEK-OCT1 (▪) cells. We incubated 5 µM extracellular drug concentration with the cells. Cell binding of the compounds was determined by dialysis using a rapid equilibrium device (RED). Intracellular space of HEK-EV (1.21 µl/10⁶ cells) and HEK-OCT1 (1.25 µl/10⁶ cells) were used to calculate the unbound intracellular concentrations of three guanidine compounds. Data are presented as mean ± S.E.M. *P < 0.05.