Organic cation transport in avian renal brush-border membrane vesicles.

Persistent Link:
http://hdl.handle.net/10150/186419
Title:
Organic cation transport in avian renal brush-border membrane vesicles.
Author:
Villalobos, Alice Renee Avila.
Issue Date:
1993
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
The objective of this study was to characterize the transport of organic cations (OCs) at the luminal brush-border membrane of the avian renal proximal tubule. Using membrane vesicles isolated from renal tissue of chickens (Gallus domesticus), transport of the exogenous OC[¹⁴C]tetraethylammonium (TEA) was measured by rapid filtration under various ionic conditions. A trans proton gradient stimulated concentrative uptake of TEA. Tetraethylammonium/proton exchange was a saturable, qualitatively symmetrical process that was indirectly coupled to Na⁺/H⁺ antiport. Proton-driven uptake of TEA was not electrogenic; however, it was sensitive to changes in transmembrane potential. Proton-driven TEA uptake was apparently selectively inhibited by OCs. To evaluate substrate specificity of OC/H⁺ exchanger, a battery of endogenous and exogenous OCs were tested for cis inhibition and trans stimulation of [¹⁴C]TEA transport. Although amiloride, cimetidine, mepiperphenidol, procainamide, quinidine, quinine, ranitidine and thiamine were potent cis inhibitors of TEA transport, they were poorly transported by the exchanger. Conversely, acetylcholine, choline, epinephrine, guanidine, isoproterenol, N¹methylnicotinamide, serotonin, and unlabeled TEA, modestly inhibited TEA transport, but trans stimulated transport. Inhibitor-induced changes in the kinetic parameters of TEA/H⁺ exchange suggested serotonin and thiamine competed with TEA for the substrate site on the exchanger, whereas inhibition by amiloride, procainamide, and quinidine apparently involved binding to allosteric sites on the carrier. These data suggest luminal transport of OCs in the avian proximal tubule is qualitatively similar to that in mammals. Moreover, the OC/H⁺ exchanger of avian BBMV has greater affinity for exogenous compounds than for endogenous compounds; however, it has a greater capacity to transport endogenous OCs than exogenous OCs.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Dissertations, Academic.; Zoology.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Physiology; Graduate College
Degree Grantor:
University of Arizona
Committee Chair:
Braun, Eldon J.

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleOrganic cation transport in avian renal brush-border membrane vesicles.en_US
dc.creatorVillalobos, Alice Renee Avila.en_US
dc.contributor.authorVillalobos, Alice Renee Avila.en_US
dc.date.issued1993en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractThe objective of this study was to characterize the transport of organic cations (OCs) at the luminal brush-border membrane of the avian renal proximal tubule. Using membrane vesicles isolated from renal tissue of chickens (Gallus domesticus), transport of the exogenous OC[¹⁴C]tetraethylammonium (TEA) was measured by rapid filtration under various ionic conditions. A trans proton gradient stimulated concentrative uptake of TEA. Tetraethylammonium/proton exchange was a saturable, qualitatively symmetrical process that was indirectly coupled to Na⁺/H⁺ antiport. Proton-driven uptake of TEA was not electrogenic; however, it was sensitive to changes in transmembrane potential. Proton-driven TEA uptake was apparently selectively inhibited by OCs. To evaluate substrate specificity of OC/H⁺ exchanger, a battery of endogenous and exogenous OCs were tested for cis inhibition and trans stimulation of [¹⁴C]TEA transport. Although amiloride, cimetidine, mepiperphenidol, procainamide, quinidine, quinine, ranitidine and thiamine were potent cis inhibitors of TEA transport, they were poorly transported by the exchanger. Conversely, acetylcholine, choline, epinephrine, guanidine, isoproterenol, N¹methylnicotinamide, serotonin, and unlabeled TEA, modestly inhibited TEA transport, but trans stimulated transport. Inhibitor-induced changes in the kinetic parameters of TEA/H⁺ exchange suggested serotonin and thiamine competed with TEA for the substrate site on the exchanger, whereas inhibition by amiloride, procainamide, and quinidine apparently involved binding to allosteric sites on the carrier. These data suggest luminal transport of OCs in the avian proximal tubule is qualitatively similar to that in mammals. Moreover, the OC/H⁺ exchanger of avian BBMV has greater affinity for exogenous compounds than for endogenous compounds; however, it has a greater capacity to transport endogenous OCs than exogenous OCs.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectDissertations, Academic.en_US
dc.subjectZoology.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplinePhysiologyen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.chairBraun, Eldon J.en_US
dc.contributor.committeememberDantzler, William H.en_US
dc.contributor.committeememberHoyer, Patricia B.en_US
dc.contributor.committeememberPajor, Ana M.en_US
dc.contributor.committeememberWright, Stephen H.en_US
dc.contributor.committeememberRenfro, J. Larryen_US
dc.identifier.proquest9408493en_US
dc.identifier.oclc720652336en_US
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