Table 3

Transport of carnitine and various organic cations by OCTN2-expressing HEK 293 cells

Compound	Uptake Time	OCTN2-Expressing Cells	C/M Ratio
Compound	Uptake Time	OCTN2-Expressing Cells	Mock Cells	Net Uptake
	min		μl/mg of protein
l-[³H]Carnitine	5	149 ± 2.00^3-150	23.3 ± 0.31	126
[³H]Acetyl-L-carnitine	5	206 ± 1.73^3-150	17.3 ± 1.31	189
[³H]Verapamil	5	1760 ± 18.7^3-150	1485 ± 31.8	275
[³H]Pyrilamine	5	577 ± 7.86^3-150	459 ± 11.0	118
[¹⁴C]TEA	30	34.1 ± 0.63^3-150	10.5 ± 0.05	23.6
[³H]MPP	30	34.7 ± 0.67^3-150	26.2 ± 0.95	8.5
[³H]PAH	30	8.4 ± 0.06	9.2 ± 0.27	−0.8

The uptakes of [³H]carnitine (10 nM), [³H]acetyl-l-carnitine (7.7 nM), [³H]verapamil (12 nM), [³H]pyrilamine (50 nM), [¹⁴C]TEA (104 μM), [³H]MPP (12 nM), and [³H]PAH (408 nM) in OCTN2-expressing HEK 293 cells were measured for 5 or 30 min at 37°C in Na⁺-containing transport buffer, pH 7.4. Each value represents the mean ± S.E.M. of three experiments by the same batch of transfected cells. C/M ratio was obtained by dividing uptake amount by the concentration of [¹⁴C]TEA in the uptake medium. Net uptake represents the difference in the uptakes between OCTN2-expressing and Mock cells.

↵3-150 , Significantly different from the uptake by Mock cells by Student's t test (p < 0.05).