scholarly journals Role for ovarian hormones in purinoceptor-dependent natriuresis

2020 ◽  
Author(s):  
Eman Gohar ◽  
Malgorzata Kasztan ◽  
Shali Zhang ◽  
Edward W Inscho ◽  
David M Pollock
Keyword(s):  
Mrna Expression ◽  
Collecting Duct ◽  
Premenopausal Women ◽  
Renal Medulla ◽  
Receptor Protein ◽  
Na Channel ◽  
Protein Abundance ◽  
Sprague Dawley ◽  
Ovx Rats ◽  
Renal Tubular

Abstract Background: Premenopausal women have a lower risk of hypertension compared to age-matched men and postmenopausal women. P2Y 2 and P2Y 4 purinoceptor can be considered potential contributors to hypertension due to their emerging roles in regulating renal tubular Na + transport. Activation of these receptors inhibits epithelial Na + channel activity (ENaC) via a phospholipase C (PLC)-dependent pathway resulting in natriuresis. We recently reported that activation of P2Y 2 and P2Y 4 receptors in the renal medulla by UTP promotes natriuresis in male and ovariectomized (OVX) rats, but not in ovary-intact females. This led us to hypothesize that ovary-intact females have greater basal renal medullary activity of P2 (P2Y 2 and P2Y 4 ) receptors regulating Na + excretion compared to male and OVX rats. Methods: To test our hypothesis, we determined (i) the effect of inhibiting medullary P2 receptors by suramin (750 μg/kg/min) on urinary Na + excretion in anesthetized male, ovary-intact female and OVX Sprague Dawley rats, (ii) mRNA expression and protein abundance of P2Y 2 and P2Y 4 receptors and (iii) mRNA expression of their downstream effectors (PLC-1d and ENaCa) in renal inner medullary tissues obtained from these three groups. We also subjectedcultured mouse inner medullary collecting duct cells (segment 3, mIMCD3) to different concentrations of 17ß-estradiol(E 2 , 0, 10, 100 and 1000 nM) to test whether E 2 increases mRNA expression of P2Y 2 and P2Y 4 receptors. Results: Acute P2 inhibition attenuated urinary Na + excretion in ovary-intact females, but not in male or OVX rats.We found that P2Y 2 and P2Y 4 mRNA expression was higher in the inner medulla from females compared to males or OVX. Inner medullary lysates showed that ovary-intact females have higher P2Y 2 receptor protein abundance, compared to males, however, OVX did not eliminate this sex difference. We also found that E 2 dose-dependently upregulated P2Y 2 and P2Y 4 mRNA expression in mIMCD3. Conclusion: These data suggest that females have enhanced P2Y 2 and P2Y 4 -dependent regulation of Na + handling in the renal medulla, compared to male and OVX rats. We speculate that the P2 pathway contributes to facilitated renal Na + handling in premenopausal females.

scholarly journals Role for ovarian hormones in purinoceptor-dependent natriuresis

2020 ◽  
Author(s):  
Eman Gohar ◽  
Malgorzata Kasztan ◽  
Shali Zhang ◽  
Edward W Inscho ◽  
David M Pollock
Keyword(s):  
Mrna Expression ◽  
Collecting Duct ◽  
Premenopausal Women ◽  
Renal Medulla ◽  
Receptor Protein ◽  
Protein Abundance ◽  
Sprague Dawley ◽  
Ovx Rats ◽  
Downstream Effectors ◽  
Renal Tubular

Abstract Background: Premenopausal women have a lower risk of hypertension compared to age-matched men and postmenopausal women. P2Y2 and P2Y4 purinoceptor can be considered potential contributors to hypertension due to their emerging roles in regulating renal tubular Na+ transport. Activation of these receptors inhibits epithelial Na+ channel activity (ENaC) via a phospholipase C (PLC)-dependent pathway resulting in natriuresis. We recently reported that activation of P2Y2 and P2Y4 receptors in the renal medulla by UTP promotes natriuresis in male and ovariectomized (OVX) rats, but not in ovary-intact females. This led us to hypothesize that ovary-intact females have greater basal renal medullary activity of P2 (P2Y2 and P2Y4) receptors regulating Na+ excretion compared to male and OVX rats. Methods: To test our hypothesis, we determined (i) the effect of inhibiting medullary P2 receptors by suramin (750 μg/kg/min) on urinary Na+ excretion in anesthetized male, ovary-intact female and OVX Sprague Dawley rats, (ii) mRNA expression and protein abundance of P2Y2 and P2Y4 receptors and (iii) mRNA expression of their downstream effectors (PLC-1d and ENaCa) in renal inner medullary tissues obtained from these three groups. We also subjected cultured mouse inner medullary collecting duct cells (segment 3, mIMCD3) to different concentrations of 17ß-estradiol (E2, 0, 10, 100 and 1000 nM) to test whether E2 increases mRNA expression of P2Y2 and P2Y4 receptors.Results: Acute P2 inhibition attenuated urinary Na+ excretion in ovary-intact females, but not in male or OVX rats. We found that P2Y2 and P2Y4 mRNA expression was higher in the inner medulla from females compared to males or OVX. Inner medullary lysates showed that ovary-intact females have higher P2Y2 receptor protein abundance, compared to males, however, OVX did not eliminate this sex difference. We also found that E2 dose-dependently upregulated P2Y2 and P2Y4 mRNA expression in mIMCD3. Conclusion: These data suggest that ovary-intact females have enhanced P2Y2 and P2Y4-dependent regulation of Na+ handling in the renal medulla, compared to male and OVX rats. We speculate that the P2 pathway contributes to facilitated renal Na+ handling in premenopausal females.

scholarly journals Role for ovarian hormones in purinoceptor-dependent natriuresis

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Eman Y. Gohar ◽  
Malgorzata Kasztan ◽  
Shali Zhang ◽  
Edward W. Inscho ◽  
David M. Pollock
Keyword(s):  
Mrna Expression ◽  
Collecting Duct ◽  
Premenopausal Women ◽  
Renal Medulla ◽  
Receptor Protein ◽  
Protein Abundance ◽  
Sprague Dawley ◽  
Ovx Rats ◽  
Downstream Effectors ◽  
Renal Tubular

Abstract Background Premenopausal women have a lower risk of hypertension compared to age-matched men and postmenopausal women. P2Y2 and P2Y4 purinoceptor can be considered potential contributors to hypertension due to their emerging roles in regulating renal tubular Na+ transport. Activation of these receptors inhibits epithelial Na+ channel activity (ENaC) via a phospholipase C (PLC)-dependent pathway resulting in natriuresis. We recently reported that activation of P2Y2 and P2Y4 receptors in the renal medulla by UTP promotes natriuresis in male and ovariectomized (OVX) rats, but not in ovary-intact females. This led us to hypothesize that ovary-intact females have greater basal renal medullary activity of P2 (P2Y2 and P2Y4) receptors regulating Na+ excretion compared to male and OVX rats. Methods To test our hypothesis, we determined (i) the effect of inhibiting medullary P2 receptors by suramin (750 μg/kg/min) on urinary Na+ excretion in anesthetized male, ovary-intact female, and OVX Sprague Dawley rats, (ii) mRNA expression and protein abundance of P2Y2 and P2Y4 receptors, and (iii) mRNA expression of their downstream effectors (PLC-1δ and ENaCα) in renal inner medullary tissues obtained from these three groups. We also subjected cultured mouse inner medullary collecting duct cells (segment 3, mIMCD3) to different concentrations of 17ß-estradiol (E2, 0, 10, 100, and 1000 nM) to test whether E2 increases mRNA expression of P2Y2 and P2Y4 receptors. Results Acute P2 inhibition attenuated urinary Na+ excretion in ovary-intact females, but not in male or OVX rats. We found that P2Y2 and P2Y4 mRNA expression was higher in the inner medulla from females compared to males or OVX. Inner medullary lysates showed that ovary-intact females have higher P2Y2 receptor protein abundance, compared to males; however, OVX did not eliminate this sex difference. We also found that E2 dose-dependently upregulated P2Y2 and P2Y4 mRNA expression in mIMCD3. Conclusion These data suggest that ovary-intact females have enhanced P2Y2 and P2Y4-dependent regulation of Na+ handling in the renal medulla, compared to male and OVX rats. We speculate that the P2 pathway contributes to facilitated renal Na+ handling in premenopausal females.

scholarly journals Potential involvement of P2Y2 receptor in diuresis of postobstructive uropathy in rats

2010 ◽  
Vol 298 (3) ◽  
pp. F634-F642 ◽  
Author(s):  
Yue Zhang ◽  
Donald E. Kohan ◽  
Raoul D. Nelson ◽  
Noel G. Carlson ◽  
Bellamkonda K. Kishore
Keyword(s):  
Mrna Expression ◽  
Collecting Duct ◽  
Receptor Activation ◽  
Receptor Expression ◽  
Urinary Concentration ◽  
Sham Operation ◽  
Protein Abundance ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Relative Mrna Expression

AVP resistance of the medullary collecting duct (mCD) in postobstructive uropathy (POU) has been attributed to increased production of PGE2. P2Y2 receptor activation causes production of PGE2 by the mCD. We hypothesize that increased P2Y2 receptor expression and/or activity may contribute to the diuresis of POU. Sprague-Dawley rats were subjected to bilateral ureteral obstruction for 24 h followed by release (BUO/R, n = 17) or sham operation (SHM/O, n = 15) and euthanized after 1 wk or 12 days. BUO/R rats developed significant polydipsia, polyuria, urinary concentration defect, and increased urinary PGE2 and decreased aquaporin-2 protein abundance in the inner medulla compared with SHM/O rats. After BUO/R, the relative mRNA expression of P2Y2 and P2Y6 receptors was increased by 2.7- and 4.9-fold, respectively, without significant changes in mRNA expression of P2Y1 or P2Y4 receptor. This was associated with a significant 3.5-fold higher protein abundance of the P2Y2 receptor in BUO/R than SHM/O rats. When freshly isolated mCD fractions were challenged with different types of nucleotides (ATPγS, ADP, UTP, or UDP), BUO/R and SHM/O rats responded to only ATPγS and UTP and released PGE2, consistent with involvement of the P2Y2, but not P2Y6, receptor. ATPγS- or UTP-stimulated increases in PGE2 were much higher in BUO/R (3.20- and 2.28-fold, respectively, vs. vehicle controls) than SHM/O (1.68- and 1.30-fold, respectively, vs. vehicle controls) rats. In addition, there were significant 2.4- and 2.1-fold increases in relative mRNA expression of prostanoid EP1 and EP3 receptors, respectively, in the inner medulla of BUO/R vs. SHM/O rats. Taken together, these data suggest that increased production of PGE2 by the mCD in POU may be due to increased expression and activity of the P2Y2 receptor. Increased mRNA expression of EP1 and EP3 receptors in POU may also help accentuate PGE2-induced signaling in the mCD.

Lack of vasopressin-independent upregulation of AQP-2 gene expression in homozygous Brattleboro rats

1999 ◽  
Vol 277 (2) ◽  
pp. R427-R433 ◽  
Author(s):  
Takako Saito ◽  
San-E Ishikawa ◽  
Sei Sasaki ◽  
Minori Higashiyama ◽  
Shoichiro Nagasaka ◽  
...  
Keyword(s):  
Gene Expression ◽  
Mrna Expression ◽  
Water Deprivation ◽  
Collecting Duct ◽  
Renal Medulla ◽  
Brattleboro Rats ◽  
Severe Dehydration ◽  
Urinary Osmolality ◽  
Independent Mechanism ◽  
Collecting Duct Cells

Arginine vasopressin (AVP) plays an important role in the expression of aquaporin (AQP-2) in the collecting duct. The present study was undertaken to determine whether there is an AVP-independent regulation of AQP-2 gene expression in homozygous Brattleboro rats in which endogenous AVP is absent. Exogenous administration of 1-deamino-8-d-AVP produced an antidiuresis and expressed AQP-2 mRNA and AQP-2 protein in the renal medulla of the homozygous Brattleboro rats. Twelve hours of water deprivation produced severe dehydration in the homozygous Brattleboro rats, such that urinary osmolality increased from 200 to 649 mosmol/kgH2O. However, no increase in AQP-2 mRNA expression was observed after this dehydration, and the medullary tissue content and urinary excretion of AQP-2 also remained unchanged. Increases in AQP-2 mRNA expression and AQP-2 protein were evident in Long-Evans rats after 64 h of water deprivation, with a severity of dehydration almost equal to the 12-h dehydrated, homozygous Brattleboro rats. These results indicate the lack of an AVP-independent mechanism for upregulating AQP-2 mRNA expression in renal collecting duct cells.

Endothelin receptor mRNA expression in renal medulla identified by in situ RT-PCR

1995 ◽  
Vol 269 (3) ◽  
pp. F449-F457 ◽  
Author(s):  
L. H. Chow ◽  
S. Subramanian ◽  
G. J. Nuovo ◽  
F. Miller ◽  
E. P. Nord
Keyword(s):  
Mrna Expression ◽  
Collecting Duct ◽  
Renal Medulla ◽  
Receptor Subtypes ◽  
Rt Pcr ◽  
Receptor Mrna ◽  
Pcr Products ◽  
Medullary Collecting Duct ◽  
Labeled Probe

Three subtypes of endothelin (ET) receptors have been identified by cDNA cloning, namely ET-RA, ET-RB, and ET-RC. In the current study the precise cellular distribution of the ET receptor subtypes in the renal medulla was explored by detecting the corresponding polymerase chain reaction (PCR)-amplified cDNAs by in situ reverse transcription (RT)-PCR. The PCR-amplified cDNAs were detected either by direct incorporation using digoxigenin-dUTP (dig-dUTP) as a nucleotide substrate in the PCR reaction or by in situ hybridization with the dig-dUTP-labeled probe. ET-RB mRNA was detected exclusively in the epithelial cells of the inner and outer medullary collecting duct. In contrast, ET-RA message was observed primarily in interstitial cells and pericytes of the vasae rectae in the outer and inner medulla. Southern blot analysis of PCR-amplified cDNAs reverse transcribed from extracted RNA of rat renal medulla confirmed the specificity of the RT-PCR products. ET-RC mRNA was not detected. We conclude that ET-RB is the major ET receptor found in rat renal medulla and is expressed exclusively on inner medullary collecting duct cells. The pattern of ET receptor mRNA expression described suggests different physiological actions for ET on the diverse cellular structures of the renal medulla.

Vasopressin receptor subtype 2 activation increases cell proliferation in the renal medulla of AQP1 null mice

2007 ◽  
Vol 293 (6) ◽  
pp. F1858-F1864 ◽  
Author(s):  
Qi Cai ◽  
Matthew R. McReynolds ◽  
Maggie Keck ◽  
Kevin A. Greer ◽  
James B. Hoying ◽  
...  
Keyword(s):  
Cyclin D1 ◽  
Collecting Duct ◽  
Renal Medulla ◽  
Nuclear Antigen ◽  
Receptor Subtype ◽  
Protein Abundance ◽  
Activating Transcription Factor 3 ◽  
Collecting Ducts ◽  
Growth Changes ◽  
Activating Transcription Factor

Aquaporin (AQP) 1 null mice have a defect in the renal concentrating gradient because of their inability to generate a hyperosmotic medullary interstitium. To determine the effect of vasopressin on renal medullary gene expression, in the absence of high local osmolarity, we infused 1-deamino-8-d-arginine vasopressin (dDAVP), a V2 receptor (V2R)-specific agonist, in AQP1 null mice for 7 days. cDNA microarray analysis was performed on the renal medullary tissue, and 5,140 genes of the possible 12,000 genes on the array were included in the analysis. In the renal medulla of AQP1 null mice, 245 transcripts were identified as increased by dDAVP infusion and 200 transcripts as decreased (1.5-fold or more). Quantitative real-time PCR measurements confirmed the increases seen for cyclin D1, early growth response gene 1, and activating transcription factor 3, genes associated with changes in cell cycle/growth. Changes in mRNA expression were correlated with changes in protein expression by semiquantitative immunoblotting; cyclin D1 and ATF3 were increased significantly in abundance following dDAVP infusion in the renal medulla of AQP1 null mice (161 and 461%, respectively). A significant increase in proliferation of medullary collecting ducts cells, following V2R activation, was identified by proliferating cell nuclear antigen immunohistochemistry; colocalization studies with AQP2 indicated that the increase in proliferation was primarily observed in principal cells of the inner medullary collecting duct (IMCD). V2R activation, via dDAVP, increased AQP2 and AQP3 protein abundance in the cortical collecting ducts of AQP1 null mice. However, V2R activation did not increase AQP2 protein abundance in the IMCD of AQP1 null mice.

Regulation of AQP6 mRNA and protein expression in rats in response to altered acid-base or water balance

2000 ◽  
Vol 279 (6) ◽  
pp. F1014-F1026 ◽  
Author(s):  
Dominique Promeneur ◽  
Tae-Hwan Kwon ◽  
Masato Yasui ◽  
Gheun-Ho Kim ◽  
Jørgen Frøkiær ◽  
...  
Keyword(s):  
Water Balance ◽  
Mrna Expression ◽  
Water Intake ◽  
Collecting Duct ◽  
Free Access ◽  
Protein Abundance ◽  
Acid Base ◽  
Urine Ph ◽  
Daily Water Intake ◽  
Acid Load

In the rat, aquaporin-6 (AQP6) is mainly localized in intercalated cells (ICs) in collecting ducts, where it is exclusively associated with intracellular vesicles. In this study, we examined whether AQP6 protein and mRNA expression were regulated in the inner medulla or inner stripe of the outer medulla. Rats treated with dietary alkali or acid load for 7 days with a fixed daily water intake revealed appropriate changes in urine pH but unchanged urine output. AQP6 protein and mRNA abundance were increased in alkali-loaded rats (187 ± 18 and 151 ± 17% of control, respectively), whereas no changes were observed in acid-loaded rats. Immunohistochemistry revealed increased IC AQP6 labeling in alkali-loaded rats but not in acid-loaded rats. In contrast, administration of NH4Cl in the drinking water for 2 wk (free access to water) revealed a significant increase in AQP6 protein abundance (194 ± 9% of control), but this was associated with increased water intake. Combined, this suggests that AQP6 expression was not affected by acid loading per se but rather was in response to changes in water intake. Consistent with this, water loading for 48 h was associated with increased AQP6 protein abundance, compared with thirsted rats. Moreover, rats with lithium-induced nephrogenic diabetes insipidus had a threefold increase in both AQP6 protein and mRNA expression. Overall, these results suggest that AQP6 expression in collecting duct ICs is regulated by altered acid/alkali load or water balance. Thus AQP6 may contribute to maintenance of acid-base homeostasis and water balance.

scholarly journals Dynamin activates NO production in rat renal inner medullary collecting ducts via protein-protein interaction with NOS1

2011 ◽  
Vol 301 (1) ◽  
pp. F118-F124 ◽  
Author(s):  
Kelly A. Hyndman ◽  
Jacqueline B. Musall ◽  
Jing Xue ◽  
Jennifer S. Pollock
Keyword(s):  
Collecting Duct ◽  
Renal Medulla ◽  
Dominant Negative ◽  
No Production ◽  
Sprague Dawley ◽  
Salt Diet ◽  
Protein Protein Interaction ◽  
Nitrite Production ◽  
Sprague Dawley Rats ◽  
Nos Isoforms

We hypothesized that nitric oxide synthase (NOS) isoforms may be regulated by dynamin (DNM) in the inner medullary collecting duct (IMCD). The aims of this study were to determine which DNM isoforms (DNM1, DNM2, DNM3) are expressed in renal IMCDs, whether DNM interacts with NOS, whether a high-salt diet alters the interaction of DNM and NOS, and whether DNM activates NO production. DNM2 and DNM3 are highly expressed in the rat IMCD, while DNM1 is localized outside of the IMCD. We found that DNM1 interacts with NOS1α, NOS1β, and NOS3 in the inner medulla of male Sprague-Dawley rats on a 0.4% salt diet. DNM2 interacts with NOS1α, while DNM3 interacts with both NOS1α and NOS1β. DNM2 and DNM3 do not interact with NOS3 in the rat inner medulla. We did not observe any change in the DNM/NOS interactions with rats on a 4% salt diet after 7 days. Furthermore, NOS1α interacts with DNM2 in mIMCD3 and COS7 cells transfected with NOS1α and DNM2-GFP constructs and the NOS1 reductase domain is necessary for the interaction. Finally, COS7 cells expressing NOS1α or NOS1α/DNM2-GFP had significantly higher nitrite production compared with DNM2-GFP only. Nitrite production was blocked by the DNM inhibitor dynasore or the dominant negative DNM2K44A. Ionomycin stimulation further increased nitrite production in the NOS1α/DNM2-GFP cells compared with NOS1α only. In conclusion, DNM and NOS1 interact in the rat renal IMCD and this interaction leads to increased NO production, which may influence NO production in the renal medulla.

scholarly journals Persistence of 1,25D-induced hypercalciuria in alendronate-treated genetic hypercalciuric stone-forming rats fed a low-calcium diet

2014 ◽  
Vol 306 (9) ◽  
pp. F1081-F1087 ◽  
Author(s):  
Kevin K. Frick ◽  
John R. Asplin ◽  
Christopher D. Culbertson ◽  
Ignacio Granja ◽  
Nancy S. Krieger ◽  
...  
Keyword(s):  
Vitamin D ◽  
Bone Density ◽  
Bone Resorption ◽  
Mrna Expression ◽  
Kidney Stones ◽  
Sprague Dawley ◽  
Vitamin D Receptors ◽  
Low Calcium Diet ◽  
Renal Tubular ◽  
Intestinal Ca Absorption

Genetic hypercalciuric stone-forming (GHS) rats demonstrate increased intestinal Ca absorption, increased bone resorption, and reduced renal tubular Ca reabsorption leading to hypercalciuria and all form kidney stones. GHS have increased vitamin D receptors (VDR) at these sites of Ca transport. Injection of 1,25(OH)2D3 (1,25D) leads to a greater increase in urine (u)Ca in GHS than in control Sprague-Dawley (SD), possibly due to the additional VDR. In GHS the increased uCa persists on a low-Ca diet (LCD) suggesting enhanced bone resorption. We tested the hypothesis that LCD, coupled to inhibition of bone resorption by alendronate (alen), would eliminate the enhanced 1,25D-induced hypercalciuria in GHS. SD and GHS were fed LCD and half were injected daily with 1,25D. After 8 days all were also given alen until euthanasia at day 16. At 8 days, 1,25D increased uCa in SD and to a greater extent in GHS. At 16 days, alen eliminated the 1,25D-induced increase in uCa in SD. However, in GHS alen decreased, but did not eliminate, the 1,25D-induced hypercalciuria, suggesting maximal alen cannot completely prevent the 1,25D-induced bone resorption in GHS, perhaps due to increased VDR. There was no consistent effect on mRNA expression of renal transcellular or paracellular Ca transporters. Urine CaP and CaOx supersaturation (SS) increased with 1,25D alone in both SD and GHS. Alen eliminated the increase in CaP SS in SD but not in GHS. If these results are confirmed in humans with IH, the use of bisphosphonates, such as alen, may not prevent the decreased bone density observed in these patients.

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