Increased Expression of Sodium Transport Proteins and NA,K-ATPase Activity in the Outer Medulla of Kangaroo Rat is Related to its Greater Urine Concentrating Ability Compared to Munich Wistar and Sprague-Dawley Rat

Persistent Link:
http://hdl.handle.net/10150/579396
Title:
Increased Expression of Sodium Transport Proteins and NA,K-ATPase Activity in the Outer Medulla of Kangaroo Rat is Related to its Greater Urine Concentrating Ability Compared to Munich Wistar and Sprague-Dawley Rat
Author:
Mun, Aw
Issue Date:
2015
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 kangaroo rat (Dipodomys merriami), a desert rodent, is able to concentrate its urine to more than 6,000 mosmol/kg water, nearly twice that of the SD rat, allowing the species to adapt in a dry environment. We hypothesize that active sodium reabsorption in the thick ascending limb (TAL) of the kangaroo rat outer medulla (OM) is greater than that of the SD rat, and plays a critical role in generating a steeper corticopapillary osmotic gradient. The OM was dissected and prepared for semi-quantitative western blotting. We measured a four-fold greater abundance of Na,K-ATPase α-1 subunit protein (NKA- α1) (n=5, p<0.0001) and nearly two-fold greater abundance of NKCC2 cotransporter and NHE3 protein expression in OM homogenates of kangaroo rat compared to SD rat (n=3, p<0.01). Three-day water restriction in SD rat (water reduced to 40% of normal consumption) did not significantly affect NKA- α1, NKCC2 and NHE3 expression (n=3, p>0.1). Na,K-ATPase (NKA) activity was measured as the difference in ATP hydrolyzed in the absence and presence of ouabain, as determined by measuring release of inorganic phosphate (Pi). OM NKA activity in kangaroo rat was significantly higher than in control SD rat, 7778 ± 973 and 4886 ± 296 nmoles ATP hydrolyzed/mg protein/30 min respectively (n=3). However, the volume of mitochondria per unit inner stripe TAL cell volume is identical in both species. We conclude that the greater urine concentrating ability in kangaroo rat compared to the SD rat is associated with greater expression of active sodium transport proteins and higher NKA activity, which increases sodium reabsorption in the TAL of the OM.
Type:
text; Electronic Thesis
Degree Name:
B.S.
Degree Level:
bachelors
Degree Program:
Honors College; Physiology
Degree Grantor:
University of Arizona
Advisor:
Pannabecker, Thomas

Full metadata record

DC FieldValue Language
dc.language.isoen_USen
dc.titleIncreased Expression of Sodium Transport Proteins and NA,K-ATPase Activity in the Outer Medulla of Kangaroo Rat is Related to its Greater Urine Concentrating Ability Compared to Munich Wistar and Sprague-Dawley Raten_US
dc.contributor.authorMun, Awen
dc.date.issued2015en
dc.publisherThe University of Arizona.en
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
dc.description.abstractThe kangaroo rat (Dipodomys merriami), a desert rodent, is able to concentrate its urine to more than 6,000 mosmol/kg water, nearly twice that of the SD rat, allowing the species to adapt in a dry environment. We hypothesize that active sodium reabsorption in the thick ascending limb (TAL) of the kangaroo rat outer medulla (OM) is greater than that of the SD rat, and plays a critical role in generating a steeper corticopapillary osmotic gradient. The OM was dissected and prepared for semi-quantitative western blotting. We measured a four-fold greater abundance of Na,K-ATPase α-1 subunit protein (NKA- α1) (n=5, p<0.0001) and nearly two-fold greater abundance of NKCC2 cotransporter and NHE3 protein expression in OM homogenates of kangaroo rat compared to SD rat (n=3, p<0.01). Three-day water restriction in SD rat (water reduced to 40% of normal consumption) did not significantly affect NKA- α1, NKCC2 and NHE3 expression (n=3, p>0.1). Na,K-ATPase (NKA) activity was measured as the difference in ATP hydrolyzed in the absence and presence of ouabain, as determined by measuring release of inorganic phosphate (Pi). OM NKA activity in kangaroo rat was significantly higher than in control SD rat, 7778 ± 973 and 4886 ± 296 nmoles ATP hydrolyzed/mg protein/30 min respectively (n=3). However, the volume of mitochondria per unit inner stripe TAL cell volume is identical in both species. We conclude that the greater urine concentrating ability in kangaroo rat compared to the SD rat is associated with greater expression of active sodium transport proteins and higher NKA activity, which increases sodium reabsorption in the TAL of the OM.en
dc.typetexten
dc.typeElectronic Thesisen
thesis.degree.nameB.S.en
thesis.degree.levelbachelorsen
thesis.degree.disciplineHonors Collegeen
thesis.degree.disciplinePhysiologyen
thesis.degree.grantorUniversity of Arizonaen
dc.contributor.advisorPannabecker, Thomasen
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