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. 2020 Sep 19;21(18):6871.
doi: 10.3390/ijms21186871.

Functional and Pharmacological Comparison of Human, Mouse, and Rat Organic Cation Transporter 1 toward Drug and Pesticide Interaction

Saskia Floerl  1 , Annett Kuehne  1 , Yohannes Hagos  1
Affiliations

Functional and Pharmacological Comparison of Human, Mouse, and Rat Organic Cation Transporter 1 toward Drug and Pesticide Interaction

Saskia Floerl et al. Int J Mol Sci. .

Abstract

Extrapolation from animal to human data is not always possible, because several essential factors, such as expression level, localization, as well as the substrate selectivity and affinity of relevant transport proteins, can differ between species. In this study, we examined the interactions of drugs and pesticides with the clinically relevant organic cation transporter hOCT1 (SLC22A1) in comparison to the orthologous transporters from mouse and rat. We determined Km-values (73 ± 7, 36 ± 13, and 57 ± 5 µM) of human, mouse and rat OCT1 for the commonly used substrate 1-methyl-4-phenylpyridinium (MPP) and IC50-values of decynium22 (12.1 ± 0.8, 5.3 ± 0.4, and 10.5 ± 0.4 µM). For the first time, we demonstrated the interaction of the cationic fungicides imazalil, azoxystrobin, prochloraz, and propamocarb with human and rodent OCT1. Drugs such as ketoconazole, clonidine, and verapamil showed substantial inhibitory potential to human, mouse, and rat OCT1 activity. A correlation analysis of hOCT1 versus mouse and rat orthologs revealed a strong functional correlation between the three species. In conclusion, this approach shows that transporter interaction data are in many cases transferable between rodents and humans, but potential species differences for other drugs and pesticides could not be excluded, though it is recommendable to perform functional comparisons of human and rodent transporters for new molecular entities.

Keywords: OCT1; SLC22A1; drugs; pesticides; solute carrier (SLC) family; species differences.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Time dependent uptake of 3H-MPP in (A) hOCT1-, (B) mOct1-, and (C) rOct1-HEK293 cells. Human, mouse, and rat organic cation transporter 1 (OCT1) transfected HEK293 cells were incubated for increasing time points at 37 °C in the presence of labeled 3H-1-methyl-4-phenylpyridinium (MPP) (2 nM), in case of hOCT1 and mOct1 the concentration was filled up to 10 µM with unlabeled MPP. Each data point represents the mean of two or three independent experiments ± average deviation. Experiments were carried out in triplicates.
Figure 2
Figure 2
Kinetics of (A) hOCT1-, (B) mOct1-, and (C) rOct1-mediated 3H-MPP transport. Human, mouse, and rat OCT1-transfected HEK293 cells were incubated for 1 min at 37 °C in the presence of labeled (2 nM) and increasing concentrations of non-labeled MPP. Net uptake was fitted to the Michaelis–Menten equation to obtain the affinity constant Km and maximum transport velocity Vmax by non-linear regression analysis using Sigma Plot 13.0 software. Each data point represents the mean of two independent experiments ± average deviation. Experiments were carried out in triplicates.
Figure 3
Figure 3
Inhibitory effects of decynium22 on (A) hOCT1-, (B) mOct1-, and (C) rOct1-mediated 3H-MPP transport in stable transfected HEK293 cells. Uptake of MPP at Km value was measured in the presence of increasing concentrations of decynium22 (1–100 µM). Each data point represents the mean inhibitory effect (%) calculated from the net-uptake of two independent experiments ± average deviation. Each experiment was carried out in triplicates. IC50 values were calculated by sigmoidal 3Hill analysis using Sigma Plot 13.0 software.
Figure 4
Figure 4
Scatter plot analysis correlating inhibitory effects of (A) hOCT1 and mOct1, (B) hOCT1 and rOct1, and (C) mOct1 and rOct1. The correlation coefficient R2 value for all three combinations is higher than 0.7, indicating a good correlation between species. Data points represent mean and standard deviation of one individual experiment. Mean values in detail are presented in Table 1 and Table 2.
Figure 5
Figure 5
Scatter plot analysis correlating inhibitory effects of (A) hOCT1 vs. hOCT2, (B) hOCT1 vs. hMATE1, (C) and hOCT2 vs. hMATE1. The correlation coefficient R2 value for the combination hOCT1 vs. hOCT2 is near 0.7, indicating a good correlation between cation transporters, while the combination hOCT1 vs. hMATE1 shows only an R2 value of 0.45 and for hOCT2 vs. hMATE1 R2 = 0.27. Data points represent mean and standard deviation of one individual experiment. Mean values are presented in detail in Table 3 and Table 4.
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