Ochratoxin A secretion in primary cultures of rabbit renal proximal tubule cells.

Primary cultures of rabbit renal proximal tubule cells grown under improved culture conditions were used to study the transepithelial transport of the nephrotoxic mycotoxin ochratoxin A. The basal-to-apical transepithelial flux, i.e., secretion, of this fluorescence organic acid was measured in primary cultures of rabbit renal proximal tubule cells. The basal-to-apical flux of ochratoxin A increased with time and reached a steady state after 12 h. On the other hand, the apical-to-basal flux, i.e., reabsorption, of ochratoxin A was minimal over time. The secretory flux of ochratoxin A was as much as eightfold greater than the reabsorptive flux, indicating that net secretion is the primary mechanism for ochratoxin A clearance by the proximal tubule. The kinetic analysis of ochratoxin A flux revealed secretion to be a saturable and very high-affinity process with an apparent K50 of 0.33 +/- 0.21 mM. A saturating concentration of the prototypical organic anion substrate para-aminohippurate (PAH) reduced ochratoxin A secretion by approximately 75%. The kinetic analysis of PAH inhibition of ochratoxin A secretion revealed an IC50 of 195 mM, which is similar to the IC50 for PAH inhibition of peritubular ochratoxin A uptake in tubule suspensions and the Km, values for peritubular PAH uptake. The organic anions probenecid, octanoate, and alpha-ketoglutarate reduced ochratoxin A excretion to the same degree as PAH, whereas the amino acid phenylalanine had a minimal effect on ochratoxin A secretion. Thus, collectively, these observations indicate that the secretion of ochratoxin A in primary cultures of rabbit renal proximal tubules is limited to the organic anion secretory pathway. The high affinity measured for the basal-to-apical flux of ochratoxin A suggests that at concentrations typical of naturally occurring exposures, transepithelial secretion by the organic anion transport pathway represents a significant avenue for excretion of this mycotoxin by the renal proximal tubule.

[1]  J. R. Welborn,et al.  Peritubular transport of ochratoxin A by single rabbit renal proximal tubules. , 1998, Journal of the American Society of Nephrology : JASN.

[2]  S. Wright,et al.  Peritubular transport of ochratoxin A in rabbit renal proximal tubules. , 1998, The Journal of pharmacology and experimental therapeutics.

[3]  K. Ullrich Renal Transporters for Organic Anions and Organic Cations. Structural Requirements for Substrates , 1997, The Journal of Membrane Biology.

[4]  S. Silbernagl,et al.  Renal transepithelial secretion of ochratoxin A in the non-filtering toad kidney. , 1997, Toxicology.

[5]  S. Silbernagl,et al.  Apical-to-basolateral transepithelial transport of Ochratoxin A by two subtypes of Madin-Darby canine kidney cells. , 1997, Biochimica et biophysica acta.

[6]  S. Silbernagl,et al.  Reabsorption of the nephrotoxin ochratoxin A along the rat nephron in vivo. , 1997, The Journal of pharmacology and experimental therapeutics.

[7]  R. Schnellmann,et al.  L-ascorbic acid regulates growth and metabolism of renal cells: improvements in cell culture. , 1996, The American journal of physiology.

[8]  R. Schnellmann,et al.  Autocrine production and TGF-beta 1-mediated effects on metabolism and viability in renal cells. , 1996, The American journal of physiology.

[9]  J. Morin,et al.  Polarity and transport properties of rabbit kidney proximal tubule cells on collagen IV-coated porous membranes. , 1995, The American journal of physiology.

[10]  R. Schnellmann,et al.  Improved culture conditions stimulate gluconeogenesis in primary cultures of renal proximal tubule cells. , 1995, The American journal of physiology.

[11]  S. Wright,et al.  Kinetics of interactions of para-aminohippurate, probenecid, cysteine conjugates and N-acetyl cysteine conjugates with basolateral organic anion transporter in isolated rabbit proximal renal tubules. , 1995, The Journal of pharmacology and experimental therapeutics.

[12]  K. Ullrich,et al.  Specificity of transporters for 'organic anions' and 'organic cations' in the kidney. , 1994, Biochimica et biophysica acta.

[13]  S. Wright,et al.  Peritubular organic cation transport in isolated rabbit proximal tubules. , 1994, The American journal of physiology.

[14]  D. Miller,et al.  Mechanisms mediating renal secretion of organic anions and cations. , 1993, Physiological reviews.

[15]  M. Takano,et al.  Transport of organic anion in the OK kidney epithelial cell line. , 1993, The American journal of physiology.

[16]  S. Silbernagl,et al.  Effect on Dome Formation and Uptake of Ochratoxin A in Proximal Tubule-Derived Opossum Kidney Cell Monolayers , 1993 .

[17]  K. Ullrich,et al.  Tissue concentration and urinary excretion pattern of sulfofluorescein by the rat kidney. , 1993, Journal of the American Society of Nephrology : JASN.

[18]  O. Flint,et al.  Characterization of rabbit primary proximal tubule kidney cell cultures grown on Millicell-HA membrane filters. , 1992, Toxicology in vitro : an international journal published in association with BIBRA.

[19]  J. Grantham,et al.  Specificity of basolateral organic anion exchanger in proximal tubule for cellular and extracellular solutes. , 1992, Journal of the American Society of Nephrology : JASN.

[20]  V. Chatsudthipong,et al.  PAH/alpha-KG countertransport stimulates PAH uptake and net secretion in isolated rabbit renal tubules. , 1992, The American journal of physiology.

[21]  V. Chatsudthipong,et al.  PAH-alpha-KG countertransport stimulates PAH uptake and net secretion in isolated snake renal tubules. , 1991, The American journal of physiology.

[22]  S. Grassl,et al.  Transepithelial acidification by cultures of rabbit proximal tubules grown on filters. , 1990, The American journal of physiology.

[23]  P. Scott,et al.  Risk assessment of the mycotoxin ochratoxin A. , 1989, Biomedical and environmental sciences : BES.

[24]  C. Ross,et al.  Mechanism of ochratoxin A transport in kidney. , 1988, The Journal of pharmacology and experimental therapeutics.

[25]  A. Schoolwerth,et al.  Renal gluconeogenesis. , 1988, Mineral and electrolyte metabolism.

[26]  R. Harvey,et al.  Renal tubular secretion and reabsorption as factors in ochratoxicosis: effects of probenecid on nephrotoxicity. , 1985, Journal of toxicology and environmental health.

[27]  A. Seawright,et al.  Experimental ochratoxicosis A in pigs. , 1984, Australian veterinary journal.

[28]  J. Grantham,et al.  Basis for heterogeneity of para-aminohippurate secretion in rabbit proximal tubules. , 1981, The American journal of physiology.

[29]  M. Pavlović,et al.  Ochratoxin a Contamination of Foodstuffs in an Area With Balkan (Endemic) Nephropathy , 1979, Acta pathologica et microbiologica Scandinavica. Section B, Microbiology.

[30]  T. Satoh,et al.  Studies on the nephrotoxicity of ochratoxin A in rats. , 1975, Toxicology and applied pharmacology.

[31]  F. Chu A comparative study of the interaction of ochratoxins with bovine serum albumin. , 1974, Biochemical pharmacology.

[32]  F. Chu Interaction of ochratoxin A with bovine serum albumin. , 1971, Archives of biochemistry and biophysics.

[33]  B. Trump,et al.  2 The Kidney , 1969 .

[34]  E. Hasselager,et al.  Studies on fungal nephrotoxicity. , 1968 .

[35]  D. A. Bennett,et al.  Renal gluconeogenesis. The effect of diet on the gluconeogenic capacity of rat-kidney-cortex slices. , 1963, The Biochemical journal.