TABLE 1

Inhibitory effect of organic cations and anions on uptake of ipratropium and tiotropium by rat kidney slices

[³H]Ipratropium (10 nM) uptake and [³H]ipratropium (10 nM) uptake by rat kidney slices were determined at 37°C and pH 7.4 for 1 min in the absence (control) and presence of an indicated inhibitor at the concentration of 1 mM. Each point represents the mean ± S.E.M. of four slices.

Inhibitor	Substrate Uptake Relative to Control
Inhibitor	[³H]Ipratropium	[³H]Tiotropium
	%
None (control)	100 ± 7.80	100 ± 2.29
Ipratropium	14.9 ± 1.31^*	25.6 ± 1.01^*
MPP⁺	23.5 ± 1.97^*	39.8 ± 1.77^*
Cimetidine	36.7 ± 1.28^*	54.5 ± 2.17^*
Quinidine	32.0 ± 2.03^*	34.9 ± 1.40^*
TEA⁺	56.9 ± 3.09^*	67.3 ± 2.51^*
Imipramine	22.7 ± 3.53^*	36.7 ± 1.92^*
PAH	88.7 ± 6.19	97.4 ± 4.30
Estrone 3-Sulfate	83.2 ± 5.67	104 ± 6.52

PAH, p-aminohippuric acid.
↵* Statistically significant difference versus control (p < 0.05) by Student's t test.