Table 3.

Uptake of various organic ions in HEK293 cells that expressed hMATE2-K at extracellular pH 7.4 after pretreatment of ammonium chloridea

CompoundsVectorhMATE2-K
Uptake (μl/mg protein per 2 min)
    [14C]TEA0.36 ± 0.047.71 ± 0.10b
    [3H]MPP3.87 ± 0.0719.5 ± 0.31b
    [3H]cimetidine1.00 ± 0.129.24 ± 0.06b
    [14C]metformin0.56 ± 0.016.68 ± 0.42b
    [14C]creatinine0.58 ± 0.050.93 ± 0.07c
    [14C]guanidine3.10 ± 0.183.71 ± 0.05c
    [14C]procainamide14.9 ± 0.1118.5 ± 0.67b
    [14C]choline7.64 ± 0.148.08 ± 0.21
    [3H]quinidine108 ± 2.01126 ± 2.21b
    [3H]quinine109 ± 0.60124 ± 5.10c
    [3H]thiamine5.98 ± 0.0612.4 ± 5.10b
    [3H]carnitine12.16 ± 0.0812.7 ± 0.26
    [14C]nicotine7.05 ± 0.327.97 ± 0.20
    [14C]captopril0.32 ± 0.010.27 ± 0.02
    [3H]verapamil24.09 ± 1.5430.5 ± 0.05c
    [14C]levofloxacin9.29 ± 0.1910.1 ± 0.83
    [3H]tetracycline3.46 ± 0.164.06 ± 0.19
    [14C]p-aminohippuric acid1.14 ± 0.031.33 ± 0.12
    [3H]glycylsarcosine0.26 ± 0.010.33 ± 0.03
Uptake (μl/mg protein per 10 min)
    NMN0.51 ± 0.032.54 ± 0.36b
    cephalexin0.13 ± 0.010.16 ± 0.03
    cefazolin0.14 ± 0.050.07 ± 0.01
    cephradine0.27 ± 0.040.30 ± 0.03
  • a HEK293 cells cultured in a 24-well plate for the uptake examination of radiolabeled compounds or cultured in a 12-well plate for unlabeled compounds were transfected with the empty vector or hMATE2-K cDNA and incubated for 20 min with incubation medium that contained 30 mM ammonium chloride. After washing, 2- or 10-min uptake measurements at extracellular pH 7.4 were carried out for radiolabeled or unlabeled compounds as described in the legend for Table 2, respectively. Data represent the mean ± SEM for three monolayers.

  • b P < 0.01,

  • c P < 0.05 significantly different from vector-transfected cells.