TABLE 3

Kinetic basis of the inhibition by NBuPy and Bmim of MATE1-mediated transport of MPP, TEMA, and NBD-MTMA

Substrate	MATE1
Substrate	J^{_max(control)^a}	J_max(inhib)^{^b}	K_{tapp(control)}^{^a}	K_tapp(inhib)^{^b}
	pmol cm⁻² min⁻¹	pmol cm⁻² min⁻¹	μM	μM
NBuPy (30 µM)
[³H]MPP (n = 3)	2.3 ± 0.45	1.8 ± 0.16	6.3 ± 0.7	61.5 ± 15.9
		P > 0.05		P < 0.05
[³H]TEMA (n = 3)	3.4 ± 0.63	4.8 ± 1.17	91.5 ± 9.1	333 ± 140
		P > 0.05		P = 0.16
NBuPy (2 µM)
[³H]NBD-MTMA (n = 7)	3.8 ± 1.2	2.9 ± 0.7	20.0 ± 3.5	108.9 ± 33.8
[³H]NBD-MTMA (n = 7)	3.8 ± 1.2	P > 0.05	20.0 ± 3.5	P < 0.05
Bmim (120 µM)
[³H]MPP (n = 3)	6.2 ± 1	7.6 ± 2.9	13.3 ± 1.4	71.3 ± 11.7
		P > 0.05		P < 0.05
[³H]TEMA (n = 2)	6.5 ± 1.1	8.1 ± 2.2	124.4 ± 26.6	366.1 ± 5.9
		P > 0.05		P < 0.05
Bmim (30 µM)
[³H] NBD-MTMA (n = 3)	2 ± 0.8	1.9 ± 0.8	15.6 ± 2.7	33.9 ± 5.4
[³H] NBD-MTMA (n = 3)	2 ± 0.8	P > 0.05	15.6 ± 2.7	P < 0.05

↵^a Values marked control were measured in the absence of inhibitor.
↵^b “inhib” values were measured in the presence of indicated concentrations of either NBuPy or Bmim. Neither inhibitor influenced J_max values, whereas K_tapp values were significantly increased over the control values.