Novel aspects of the transport of organic anions by the malpighian tubules of Drosophila melanogaster

2000 ◽  
Vol 203 (23) ◽  
pp. 3575-3584 ◽  
Author(s):  
S.M. Linton ◽  
M.J. O'Donnell
Keyword(s):  
Drosophila Melanogaster ◽  
Organic Acid ◽  
Organic Anion ◽  
Indigo Carmine ◽  
Organic Anions ◽  
Malpighian Tubules ◽  
Principal Cells ◽  
Anion Transporters ◽  
Mode Of Transport

Para-aminohippuric acid (PAH) is a negatively charged organic ion that can pass across the epithelium of Malpighian tubules. Its mode of transport was studied in Malpighian tubules of Drosophila melanogaster. PAH transport was an active process, with a K(m) of 2. 74 mmol l(−)(1) and a V(max) of 88.8 pmol min(−)(1). Tubules had a low passive permeability to PAH, but PAH transport rates (832 nmol min(−)(1)mm(2)) and concentrative ability ([PAH](secreted fluid):[PAH](bath)=81.2) were the highest measured to date for insects. Competition experiments indicated that there were two organic anion transporters, one that transports carboxylate compounds, such as PAH and fluorescein, and another that transports sulphonates, such as amaranth and Indigo Carmine. PAH transport appears to be maximal in vivo because the rate of transport by isolated tubules is not increased when these are challenged with cyclic AMP, cyclic GMP, leucokinin I or staurosporine. Basolateral PAH transport was inhibited by ouabain and dependent on the Na(+) gradient. The Malpighian tubules appeared not to possess an organic acid/ α -keto acid exchanger because PAH accumulation was not affected by low concentrations (100 μmol l(−)(1)) of α -keto acids (α -ketoglutarate, glutarate, citrate and succinate) or the activity of phosphokinase C. PAH transport may be directly coupled to the Na(+) gradient, perhaps via Na(+)/organic acid cotransport. Fluorescence microscopy showed that transport of the carboxylate fluorescein was confined to the principal cells of the main (secretory) segment and all the cells of the lower (reabsorptive) segment. Organic anions were transported across the cytoplasm of the principal cells both by diffusion and in vesicles. The accumulation of punctate fluorescence in the lumen is consistent with exocytosis of the cytoplasmic vesicles. Apical PAH transport was independent of the apical membrane potential and may not occur by an electrodiffusive mechanism.

scholarly journals Multiplicity of Hepatic Excretory Mechanisms for Organic Anions

1969 ◽  
Vol 53 (2) ◽  
pp. 238-247 ◽  
Author(s):  
Seymour Alpert ◽  
Michael Mosher ◽  
Alan Shanske ◽  
Irwin M. Arias
Keyword(s):  
Biliary Excretion ◽  
Organic Anion ◽  
Organic Anions ◽  
Bile Pigment ◽  
Johnson Syndrome ◽  
One Step

Previous studies based upon competition between different organic anions for biliary excretion in vivo have suggested that all organic anions share a common hepatic secretory mechanism. Corriedale sheep with an inherited defect in organic anion excretion by the liver were used to study this problem directly without the need for competition studies, the results of which are difficult to analyze. Maximal biliary excretion of sulfobromphthalein (BSP) in mutant Corriedale sheep was less than 7% of that observed in normal sheep whereas maximal biliary excretion of taurocholate, the major organic anion in sheep bile, was not different in mutant and normal sheep. Taurocholate infusion enhanced maximal hepatic excretion of BSP in normal but not in mutant sheep. These studies of an inheritable disorder which appears to be identical to the Dubin-Johnson syndrome in man, demonstrate that taurocholate excretion requires at least one step in biliary excretion which is not required by other organic anions such as bile pigment, porphyrins, drugs, and dyes.

Transient expression of oatp organic anion transporter in mammalian cells: identification of candidate substrates

1996 ◽  
Vol 270 (2) ◽  
pp. F319-F325 ◽  
Author(s):  
N. Kanai ◽  
R. Lu ◽  
Y. Bao ◽  
A. W. Wolkoff ◽  
V. L. Schuster
Keyword(s):  
Hela Cell ◽  
Transient Expression ◽  
Mammalian Cells ◽  
Xenopus Oocytes ◽  
Organic Anion ◽  
Expression System ◽  
Indigo Carmine ◽  
Organic Anions ◽  
Phenol Red ◽  
Cell Monolayers

The cDNA for the rat liver organic anion-transporting polypeptide "oatp" has been shown to encode transport of bromosulfophthalein (BSP) and bile salts in Xenopus oocytes (E. Jacquemin, B. Hagenbuch, B. Stieger, A. W. Wolkoff, and P. J. Meier. Proc. Natl. Acad. Sci. USA 91: 133-137, 1994). Because oatp mRNA is expressed strongly in the kidney, we sought to determine whether renal oatp might play a role in the known secretion of a large variety of organic anions by the kidney. We transiently expressed a full-length oatp cDNA, cloned in pSPORT, in HeLa cell monolayers using the recombinant vaccinia virus vtf7-3. We tested an array of organic anions as candidate substrates by determining their ability to compete with tracer BSP for transport. HeLa cell monolayers transfected with the oatp cDNA transported tracer BSP and taurocholate at rates substantially higher than monolayers transfected with a control plasmid. Thus good expression can be obtained with the vaccinia-HeLa system using a standard plasmid cloning vector. BSP transport varied as a function of the medium albumin, ionic conditions, and pH in a fashion similar to that in Xenopus oocytes. Several organic anions known to be secreted by the classic secretory pathway, including p-aminohippurate (PAH), phenol red, and indigo carmine (10 microM) failed to inhibit oatp-mediated BSP transport. Direct testing using tracers revealed no oatp-mediated transport of sulfate, urate, PAH, several eicosanoids, or unconjugated or conjugated bilirubin. On the other hand, BSP transport was inhibited by approximately 50% by 10 microM corticosterone sulfate, spironolactone, and several other steroids. We conclude that the functional properties of oatp expressed in the HeLa cell/vaccinia transient expression system are comparable to those following expression in Xenopus oocytes and that steroids are likely to represent high-affinity endogenous oatp substrates. The latter hypothesis is addressed in greater detail in a companion paper.

Downregulation of organic anion transporters OAT1 and OAT3 correlates with impaired secretion of para-aminohippurate after ischemic acute renal failure in rats

2007 ◽  
Vol 292 (5) ◽  
pp. F1599-F1605 ◽  
Author(s):  
R. Schneider ◽  
C. Sauvant ◽  
B. Betz ◽  
M. Otremba ◽  
D. Fischer ◽  
...  
Keyword(s):  
Renal Failure ◽  
Acute Renal Failure ◽  
Organic Anion ◽  
Organic Anions ◽  
Organic Anion Transporters ◽  
Protein Levels ◽  
Anion Transporters ◽  
Pah Clearance ◽  
Ischemic Acute Renal Failure

Ischemic acute renal failure (iARF) was described to reduce renal extraction of the organic anion para-aminohippurate (PAH) in humans. The rate-limiting step of renal organic anion secretion is its basolateral uptake into proximal tubular cells. This process is mediated by the organic anion transporters OAT1 and OAT3, which both have a broad spectrum of substrates including a variety of pharmaceutics and toxins. Using a rat model of iARF, we investigated whether impairing the secretion of the organic anion PAH might be associated with downregulation of OAT1 or OAT3. Inulin and PAH clearance was determined starting from 6 up to 336 h after ischemia-reperfusion (I/R) injury. Net secretion of PAH was calculated and OAT1 as well as OAT3 expression was analyzed by RT-PCR and Western blotting. Inulin and PAH clearance along with PAH net secretion were initially diminished after I/R injury with a gradual recovery during follow-up. This initial impairment after iARF was accompanied by decreased mRNA and protein levels of OAT1 and OAT3 in clamped animals compared with sham-operated controls. In correlation to the improvement of kidney function, both mRNA and protein levels of OAT1 and OAT3 were upregulated during the follow-up. Thus decreased expression of OAT1 and OAT3 is sufficient to explain the decline of PAH secretion after iARF. As a result, this may have substantial impact on excretion kinetics and half-life of organic anions. As a consequence, the biological effects of a variety of organic anions may be affected after iARF.

Developmental expression of renal organic anion transporters in rat kidney and its effect on renal secretion of phenolsulfonphthalein

2012 ◽  
Vol 302 (12) ◽  
pp. F1640-F1649 ◽  
Author(s):  
Maki Nomura ◽  
Hideyuki Motohashi ◽  
Hiroko Sekine ◽  
Toshiya Katsura ◽  
Ken-ichi Inui
Keyword(s):  
Protein Expression ◽  
Organic Anion ◽  
Immunohistochemical Analysis ◽  
Tubular Secretion ◽  
Organic Anion Transporters ◽  
Adult Rats ◽  
Anion Transporters ◽  
Anionic Drugs ◽  
Clearance Study

Organic anion transporters (OAT1 and OAT3) and multidrug resistance-associated proteins (MRP2 and MRP4) play important roles in anionic drug secretion in renal proximal tubules. Changes in the expression of such transporters are considered to affect the tubular secretion of anionic drugs. The purpose of this study was to elucidate the developmental changes in the expression of OAT1, OAT3, MRP2, and MRP4 and their effects on the tubular secretion of drugs. The mRNA level of each transporter was measured by real-time PCR, and the protein expression was evaluated by Western blotting and immunohistochemical analysis. In addition, the tubular secretion of phenolsulfonphthalein (PSP) in infant (postnatal day 14) and adult rats was estimated based on in vivo clearance study. The protein expression of organic anion transporters were very low at postnatal day 0 and gradually increased with age. In postnatal day 14 rats, the expression of OAT1 and OAT3 seemed to be at almost mature levels, while MRP2 and MRP4 seemed to be at immature levels. Immunohistochemical analysis in the kidney of postnatal day 0 rats revealed OATs on the basolateral membrane and MRPs on the brush-border membrane. At postnatal day 0, the distribution of these transporters was restricted to the inner cortical region, while after postnatal day 14, it was identical to that in adult kidney. An in vivo clearance study revealed that the tubular secretion of PSP was significantly lower in postnatal day 14 rats than adult rats. These results indicate that age-dependent changes in organic anion transporter expression affect the tubular secretion of anionic drugs in pediatric patients.

Potent Inhibitors of Organic Anion Transporters 1 and 3 From Natural Compounds and Their Protective Effect on Aristolochic Acid Nephropathy

2020 ◽  
Vol 175 (2) ◽  
pp. 279-291
Author(s):  
Caiyu Li ◽  
Xue Wang ◽  
Yajuan Bi ◽  
Heshui Yu ◽  
Jing Wei ◽  
...  
Keyword(s):  
Drug Interactions ◽  
Natural Compound ◽  
Aristolochic Acid ◽  
Organic Anion ◽  
Critical Role ◽  
Natural Compounds ◽  
Organic Anion Transporters ◽  
Herbal Products ◽  
Anion Transporters

Abstract Organic anion transporters 1 and 3 (OAT1 and OAT3) play a critical role in renal drug-drug interactions and are involved in the nephrotoxicity of many anionic xenobiotics. To date, relatively little is known about the interaction of natural compounds with OAT1 and OAT3. Of the 270 natural compounds screened in the present study, 21 compounds inhibited OAT1 and 45 compounds inhibited OAT3. Further concentration-dependent studies identified 7 OAT1 inhibitors and 10 OAT3 inhibitors with IC50 values of <10 μM, and most of them were flavonoids, the most commonly ingested polyphenolic compounds in the diet and herbal products. Computational modeling of OAT1 and OAT3 revealed the important residues for the recognition of inhibitors. The two strong OAT inhibitors, namely wedelolactone and wogonin, were evaluated for their in vivo interactions with the OAT substrate aristolochic acid I (AAI), a natural compound causing aristolochic acid-induced nephropathy (AAN) in many species. The cytotoxicity of AAI increased in two OAT-overexpressing cell lines, with more cytotoxicity in OAT1-overexpressing cells, suggesting a more important role of OAT1 than OAT3 in AAN. Both wedelolactone and wogonin markedly increased serum AAI concentrations in AAI-treated rats and ameliorated kidney injuries in AAI-treated mice. To conclude, the present findings are of significant value in understanding natural compound-drug interactions and provide a natural source for developing treatments for AAN.

Erythropoietin alters the pharmacokinetics of organic anions mainly eliminated by the kidney in rats

2021 ◽  
Vol 99 (4) ◽  
pp. 368-377
Author(s):  
María Julia Severin ◽  
María Herminia Hazelhoff ◽  
Romina Paula Bulacio ◽  
María Eugenia Mamprin ◽  
Anabel Brandoni ◽  
...  
Keyword(s):  
Organic Anion ◽  
Elimination Rate ◽  
Renal Tissue ◽  
Organic Anions ◽  
Saline Control ◽  
Control Group ◽  
Anion Transporters ◽  
Male Wistar Rats ◽  
Pah Clearance ◽  
Renal Expression

Erythropoietin (EPO) is a cytokine originally used for its effects on the hematopoietic system, and is widely prescribed around the world. In the present study, the effects of EPO administration on p-aminohippurate (PAH, a prototype organic anion) pharmacokinetics and on the renal expression of PAH transporters were evaluated. Male Wistar rats were treated with EPO or saline (control group). After 42 h, PAH was administered, and plasma samples were obtained at different time points to determine PAH levels. PAH levels in renal tissue and urine were also assessed. The renal expression of PAH transporters was evaluated by Western blotting. EPO-treated rats showed an increase in PAH systemic clearance, in its elimination rate constant, and in urinary PAH levels, while PAH in renal tissue was decreased. Moreover, EPO administration increased the expression of the transporters of the organic anions evaluated. The EPO-induced increase in PAH clearance is accounted for by the increase in its renal secretion mediated by the organic anion transporters. The goal of this study is to add important information to the wide knowledge gap that exists regarding drug–drug interactions. Owing to the global use of EPO, these results are useful in terms of translation into clinical practice.

Transport of cimetidine by flounder and human renal organic anion transporter 1

2003 ◽  
Vol 284 (3) ◽  
pp. F503-F509 ◽  
Author(s):  
Birgitta C. Burckhardt ◽  
Stefan Brai ◽  
Sönke Wallis ◽  
Wolfgang Krick ◽  
Natascha A. Wolff ◽  
...  
Keyword(s):  
Organic Anion ◽  
Human Kidney ◽  
Organic Anion Transporter ◽  
In Vivo Studies ◽  
Xenopus Laevis Oocytes ◽  
Organic Anion Transporters ◽  
Anion Transporters ◽  
Anion Transporter ◽  
Inward Currents

The H2-receptor antagonist cimetidine is efficiently excreted by the kidneys. In vivo studies indicated an interaction of cimetidine not only with transporters for basolateral uptake of organic cations but also with those involved in excretion of organic anions. We therefore tested cimetidine as a possible substrate of the organic anion transporters cloned from winter flounder (fROAT) and from human kidney (hOAT1). Uptake of [3H]cimetidine into fROAT-expressing Xenopus laevis oocytes exceeded uptake into control oocytes. At −60-mV clamp potential, 1 mM cimetidine induced an inward current, which was smaller than that elicited by 0.1 mM PAH. Cimetidine concentrations exceeding 0.1 mM decreased PAH-induced inward currents, indicating interaction with the same transporter. At pH 6.6, no current was seen with 0.1 mM cimetidine, whereas at pH 8.6 a current was readily detectable, suggesting preferential translocation of uncharged cimetidine by fROAT. Oocytes expressing hOAT1 also showed [3H]cimetidine uptake. These data reveal cimetidine as a substrate for fROAT/hOAT1 and suggest that organic anion transporters contribute to cimetidine excretion in proximal tubules.

Separate control of anion and cation transport in malpighian tubules of Drosophila Melanogaster.

1996 ◽  
Vol 199 (5) ◽  
pp. 1163-1175 ◽  
Author(s):  
M J O'Donnell ◽  
J A Dow ◽  
G R Huesmann ◽  
N J Tublitz ◽  
S H Maddrell
Keyword(s):  
Drosophila Melanogaster ◽  
Cyclic Amp ◽  
Cyclic Gmp ◽  
Cyclic Nucleotides ◽  
Anion Transport ◽  
Malpighian Tubules ◽  
Potential Profile ◽  
Chloride Permeability ◽  
Principal Cells ◽  
Pass Through

Microelectrode measurements of basal, apical and transepithelial potentials in the Malpighian tubules of Drosophila melanogaster were obtained under a range of conditions in order to investigate whether each of the three main second messenger systems known to act in the tubules (cyclic AMP, cyclic GMP and Ca2+) acted specifically on either cation or anion transport, or whether they activated both systems. Ion-selective microelectrode determinations of K+ concentration and pH of secreted fluid allowed the role of each signalling system to be analysed further. Stimulation with cyclic nucleotides markedly alters the potential profile across principal cells through the selective activation of an apical electrogenic V-ATPase. By contrast, manipulation of extracellular chloride levels, combined with stimulation with leucokinin, does not affect the potential profile across the principal cells, showing that chloride must pass through another route. The cell-permeant Ca2+ chelator BAPTA-AM was shown to suppress the action of leucokinins (insect peptides that induce rapid fluid secretion), but not those of cyclic AMP, the neuronally derived insect peptide cardioacceleratory peptide 2b (CAP2b) or its intracellular messenger cyclic GMP. This shows that leucokinins act through Ca2+ and not through cyclic nucleotides and that the cyclic nucleotide pathways do not co-activate the intracellular Ca2+ pathway to exert their effects. Taken together, these results show that leucokinin acts through intracellular Ca2+, independently of cyclic AMP or cyclic GMP, to raise the chloride permeability of the epithelium. By contrast, either cyclic AMP or cyclic GMP (upon CAP2b stimulation) acts on the electrogenic cation-transporting apical V-ATPase, with only a negligible effect on anion conductance and without perturbing intracellular [Ca2+]. There is thus a clear functional separation between the control pathways acting on cation and anion transport in the tubules. Given the evidence from D. melanogaster and other species that chloride does not pass through the principal cells, we speculate that these two pathways may also be physically separated within cell subtypes of the tubules.

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