TABLE 1

Inhibitory effects of several compounds on l-[3H]carnitine uptake by HEK293/PDZK1, HEK293/PDZK2, and HEK293 cells transiently expressing YFP-OCTN2

HEK293/PDZK1, HEK293/PDZK2, and HEK293 cells were transiently transfected with YFP-OCTN2 or pEYFP-C1 vector alone, and uptake of l-[3H]carnitine was then measured for 3 min at 37° C in the absence (control) or presence of each compound. Each value represents the mean ± S.E.M. of three determinations. OCTN2-mediated uptake was shown after subtracting the uptake by mock cells from that by OCTN2 (n = 3–6).

Inhibitor
Conc.
Relative Uptake (Percentage of Control)
HEK293/PDZK1
HEK293/PDZK2
HEK293
mM
Control 100 ± 2 100 ± 6 100 ± 5
l-Carnitine 0.05 7.60 ± 0.24* 9.09 ± 0.46* 14.5 ± 0.6*
l-Carnitine 1 0.00 ± 0.25* 1.82 ± 0.49* 4.16 ± 0.70*
TEA 0.5 70.0 ± 0.85* 61.8 ± 3.0* 70.6 ± 2.97*
TEA 1 55.3 ± 0.8* 51.1 ± 2.38* 55.3 ± 2.3*
Verapamil 0.05 7.68 ± 0.92* 11.9 ± 0.7* 18.3 ± 1.5*
Verapamil 1 0.01 ± 0.01* 2.32 ± 0.31* 4.97 ± 3.7*
Procainamide 1 53.3 ± 0.8* 51.1 ± 2.38* 56.1 ± 2.2*
Procainamide 5 23.2 ± 0.9* 21.9 ± 1.0* 24.1 ± 0.9*
NMN 1 85.9 ± 0.7* 81.1 ± 3.5 79.8 ± 3.0*
NMN
5
87.2 ± 0.7*
67.6 ± 3.7*
84.9 ± 3.5

  • NMN, N-methylnicotinamide.

  • ↵* Significantly different from the control (p < 0.01).