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. Author manuscript; available in PMC: 2008 Jun 1.
Published in final edited form as: Toxicol Appl Pharmacol. 2007 Mar 23;221(2):251–260. doi: 10.1016/j.taap.2007.03.004

Figure 3.

Figure 3

Saturation kinetics of the transport of inorganic mercury (Hg2+) as a conjugate of cysteine (Cys-S-Hg-S-Cys) or homocysteine (Hcy-S-Hg-S-Hcy) in ARPE-19 cells. Cells were exposed to 5 μM Cys-S-Hg-S-Cys (A) or Hcy-S-Hg-S-Hcy (B) in the presence of unlabeled Cys-S-Hg-S-Cys or Hcy-S-Hg-S-Hcy, respectively, for 30 min at 37°C and 4°C. Uptake was measured in the presence of NaCl or N-methyl-D-glucamine (NMDG). Curves were obtained using nonlinear regression analyses with the Michaelis-Menten equation: y = ax/(b+x). Panel A: NaCl: y = 111x/(160 + x), r2 = 0.995. NMDG: y = 24.8x/(195.0 + x), r2 = 0.989. Panel B: NaCl: y =85x/(78 + x) r2 = 0.995. NMDG: y = 21x/(48 + x) r2 = 0.937. Results are presented as means ± standard error. Data represent two experiments performed in triplicate. *, significantly different (p < 0.05) from the mean for the corresponding group of cells exposed at 4°C. **, significantly different (p < 0.05) from the means of all other corresponding groups of cells. +, ++, +++, or ++++ significantly (p < 0.05) from the mean for the same treatment group at previous concentrations.