Abstract
Renal excretion is an important elimination pathway for antiviral agents, such as acyclovir (ACV), ganciclovir (GCV), and zidovudine (AZT). The purpose of this study was to elucidate the molecular mechanisms of renal ACV, GCV, and AZT transport using cells stably expressing human organic anion transporter 1 (hOAT1), hOAT2, hOAT3, and hOAT4, and human organic cation transporter 1 (hOCT1) and hOCT2. Time- and concentration-dependent uptake of ACV and GCV was observed in hOAT1- and hOCT1-expressing cells. In contrast, uptake of valacyclovir,l-valyl ester of ACV, was observed only in hOAT3-expressing cells. On the other hand, AZT uptake was observed in hOAT1-, hOAT2-, hOAT3-, and hOAT4-expressing cells. The Kmvalues of ACV uptake by hOAT1 and hOCT1 were 342.3 and 151.2 μM, respectively, whereas those of GCV uptake by hOAT1 and hOCT1 were 895.5 and 516.2 μM, respectively. On the other hand, theKm values of AZT uptake by hOAT1, hOAT2, hOAT3, and hOAT4 were 45.9, 26.8, 145.1, and 151.8 μM, respectively. In addition, probenecid weakly inhibited the hOAT1-mediated ACV uptake. In conclusion, these results suggest that hOAT1 and hOCT1 mediate renal ACV and GCV transport, whereas hOAT1, hOAT2, hOAT3, and hOAT4 mediate renal AZT transport. In addition, l-valyl ester appears to be important in differential substrate recognition between hOAT1 and hOAT3. hOAT1 may not be the molecule responsible for the drug interaction between ACV and probenecid.
Footnotes
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This study was supported in part by Grants-in-Aid 11671048, 11694310, and 13671128 from the Ministry of Education, Culture, Sports, Sciences and Technology, the Science Research Promotion Fund of the Japan Private School Promotion Foundation, and Research on Health Sciences focusing on Drug Innovation from Japan Health Sciences Foundation.
- Abbreviations:
- ACV
- acyclovir
- hOAT
- human organic anion transporter
- hOCT
- human organic cation transporter
- GCV
- ganciclovir
- VACV
- valacyclovir
- AZT
- zidovudine
- S1
- S2, and S3, the first, second, and third segment of proximal tubule
- TEA
- tetraethylammonium
- D-PBS
- Dulbecco's modified phosphate-buffered saline
- PGF2α
- prostaglandin F2α
- PAH
- para-aminohippuric acid
- HIV
- human immunodeficiency virus
- Received August 28, 2001.
- Accepted November 11, 2001.
- The American Society for Pharmacology and Experimental Therapeutics
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