Alteration in Renal Organic Anion Transporter 1 After Ischemia/Reperfusion in Cadaveric Renal Allografts

Abstract

We have previously shown that postischemic injury to renal allografts results in profound impairment of p-aminohippuric acid (PAH) extraction. To elucidate the cellular integrity of the human organic anion transporter 1 (hOAT1) in postischemic acute renal failure (ARF), immunohistochemical analysis of hOAT1 was performed in cadaveric renal allografts using confocal microscopy for three-dimensional reconstruction of serial optical images. Biopsy samples were obtained from 10 cadaveric renal allografts 1 hr after reperfusion during transplant operation. Control tissues were obtained from four living donors of healthy kidneys immediately before an arterial clamp was applied to the renal artery. Control tissues demonstrated hOAT1 distributed to basolateral membrane of proximal tubule cells. In contrast, maldistribution of hOAT1 to cytoplasm and/or diminution of the protein was noted in cadaveric allografts. Characteristics of maldistribution were variable: disappearance of lateral distribution, diffuse cytoplasmic aggregates, apical cytoplasmic aggregates, and disappearance of the staining. In addition, iothalamate and PAH clearances were performed on posttransplant days 3–7 in 18 recipients of a cadaveric renal allograft. PAH clearance was depressed <250 ml/min in all but three subjects. We conclude that reperfused, transplanted kidneys exhibit maldistribution of hOAT1 in proximal tubule cells, resulting in impairment of PAH clearance. This manuscript contains online supplemental material at http://www.jhc.org . Please visit this article online to view these materials.

Toward a Systems Level Understanding of Organic Anion and Other Multispecific Drug Transporters: A Remote Sensing and Signaling Hypothesis

“…PAH clearance has been reported to be decreased in recipients of cadaveric renal allografts 3 to 7 days after transplant; immunohistochemical analyses of these renal allografts have shown altered distribution of hOat1 from the basolateral membrane of proximal tubule cells to the cytoplasm (Kwon et al, 2007). In rat kidneys subjected to ischemia/reperfusion injury, reduced clearance of PAH was also observed, together with a decreased expression of both Oat1 and Oat3 protein and mRNA levels (Matsuzaki et al, 2007;Schneider et al, 2007;Di Giusto et al, 2008).…”

The Kidney and Uremic Toxin Removal: Glomerulus or Tubule?

“…25,26 Similarly, decreased human (h)OAT1, or rOat1 and rOat3, protein expression was observed in acute renal failure patients or animals with experimentally induced acute renal failure. [27][28][29][30] Renal proximal tubule cell loss owing to injury is likely a major contributing factor to this decrease in total protein expression level.…”

Renal organic anion transporter 1 is maldistributed and diminishes in proximal tubule cells but increases in vasculature after ischemia and reperfusion

“…In this study, we aimed to elucidate pathophysiological and cellular mechanisms responsible for reduction in solute clearance via renal tubules after ischemia and recovery from it. Recently, our group (16) reported that, in cadaveric renal allografts, OAT1 was remarkably maldistributed after ischemia and reperfusion and PAH clearances were depressed. The values of net tubular PAH secretion were quite variable even at the same level of glomerular filtration rate (16).…”

“…We then visualized RNA (18S and 28S bands) using the Agilent 2100 Bioanalyzer (Agilent Technologies, Palo Alto, CA), and concentrations were adjusted. First-strand cDNA was then produced from 1.0 g of total RNA using oligo(dT) [12][13][14][15][16][17][18] primers or random hexamer primers (assay ID Rn00568143_m1; Applied Biosystems, Foster City, CA) and the SuperScript III reverse transcription kit (Invitrogen, Carlsbad, CA) by standard methods. The concentration and quality of resulting cDNA were quantified and analyzed with the Agilent 2100 Bioanalyzer or spectroscopically with the NanoDrop ND-1000 (NanoDrop Technologies, Wilmington, DE).…”

“…OAT1 has the highest affinity for PAH among the renal OAT isoforms and is located on the basolateral membrane of PT cells (2,11,21,32,38). Recently, our group (16) has reported that, in recipients of cadaveric renal allografts, the transplanted kidneys exhibit maldistribution of OAT1 in PT cells after ischemia and reperfusion, resulting in impairment of PAH clearance. In the present study, we used a rat model of ischemia and reperfusion to characterize renal OAT1 systematically during a severe form of ischemic AKI.…”