Functional and molecular aspects of prostaglandin E receptors in the cortical collecting duct

1995 ◽  
Vol 73 (2) ◽  
pp. 172-179 ◽  
Author(s):  
Richard L. Hébert ◽  
Richard M. Breyer ◽  
Harry R. Jacobson ◽  
Matthew D. Breyer
Keyword(s):  
In Situ Hybridization ◽  
Cyclic Amp ◽  
Water Transport ◽  
Collecting Duct ◽  
Prostaglandin E ◽  
Receptor Subtypes ◽  
Cortical Collecting Duct ◽  
Endogenous Prostaglandin ◽  
Ep Receptor

Endogenous prostaglandin (PG) E2 production potently modulates salt and water transport in the kidney. Multiple direct effects of PGE2 on epithelial water and sodium transport have been demonstrated in the rabbit cortical collecting duct (CCD). Both functional and molecular studies now suggest that these disparate effects of PGE2 on CCD function are mediated by different EP receptors. When added in the presence of vasopressin, PGE2 inhibits cyclic AMP generation and water absorption. These effects are mediated via an inhibitory G-protein (Gi). In situ hybridization demonstrates high levels of expression of the Gi-coupled EP3 receptor in the rabbit collecting duct. However, by itself, PGE2 also stimulates cyclic AMP generation and water permeability. These effects appear to be mediated via a distinct EP receptor (possibly an EP4 receptor). PGE2 also increases intracellular Ca2+ in the CCD and inhibits Na+ absorption via a Ca2+-dependent mechanism. The EP1 receptor is postulated to be responsible for this action of PGE2. We suggest receptor-selective prostaglandin analogs may be used to selectively modulate sodium and water transport in the kidney.Key words: EP receptor subtypes, G-proteins, in situ hybridization, prostaglandin E2, phosphatidylinositol biphosphate hydrolysis.

Differential localization of prostaglandin E receptor subtypes in human kidney

1996 ◽  
Vol 270 (5) ◽  
pp. F912-F918 ◽  
Author(s):  
M. D. Breyer ◽  
L. Davis ◽  
H. R. Jacobson ◽  
R. M. Breyer
Keyword(s):  
In Situ Hybridization ◽  
Collecting Duct ◽  
Human Kidney ◽  
Prostaglandin E ◽  
Receptor Subtypes ◽  
Ep Receptors ◽  
Inner Medullary Collecting Duct ◽  
Ep Receptor ◽  
Medullary Collecting Duct

Four prostaglandin E2 (PGE2) receptors designated EP1, EP2, EP3, and EP4 have been pharmacologically identified, cloned, and sequenced. The present studies determined the intrarenal distribution of these EP-receptor subtypes in human kidney using in situ hybridization with riboprobes for the human EP receptors. mRNA for the phosphatidylinositol hydrolysis-coupled EP receptor was highly expressed in cortical, outer medullary, and inner medullary collecting duct. RNA for the Gi-coupled EP3 receptor was primarily expressed in the cortical and outer medullary collecting duct, as well as in the medullary thick ascending limb; however, it was absent from the inner medullary collecting duct. Expression of mRNA for EP1 and EP3 in connecting segment could not be excluded. There was no expression of the GS-coupled EP2 receptor mRNA detected in human kidney by in situ hybridization; however, mRNA for the GS-coupled EP4 receptor was highly expressed in the glomerulus. These studies demonstrate distinct regions of intrarenal expression for the different EP receptors and suggest that each receptor subtype may modulate different aspects of renal function in humans.

scholarly journals Collecting duct PGE2 responses reduce water loss with empagliflozin in mice with type 2 diabetes mellitus

2021 ◽  
Vol 5 (1) ◽  
pp. 023-030
Author(s):  
Nasrallah R ◽  
Zimpelmann J ◽  
Cheff V ◽  
Thibodeau JF ◽  
Burns KD ◽  
...  
Keyword(s):  
Water Transport ◽  
Water Loss ◽  
Collecting Duct ◽  
Quantitative Polymerase Chain Reaction ◽  
Receptor Subtypes ◽  
Diabetic Mice ◽  
Water Reabsorption ◽  
Receptor System ◽  
Ep Receptor

Introduction: Sodium-glucose cotransporter 2 inhibitors such as empagliflozin (EMPA) protect against diabetic kidney disease. Prostaglandin E2 (PGE2) the main renal product of cyclooxygenase-2, inhibits vasopressin (AVP)-water reabsorption in the collecting duct (CD). The novelty of this study is that for the first time, we examined if EMPA affects the renal PGE2/EP receptor system and determined if CD responses to EMPA prevent water loss. Methods: Four groups of adult male mice were studied after 6 weeks of treatment: control (db/m), db/m+EMPA (10 mg/kg/day in chow), type 2 diabetic diabetic/dyslipidemia (db/db), and db/db+EMPA. Tubules were microdissected for quantitative polymerase chain reaction (qPCR) and CD water transport was measured in response to AVP, with or without PGE2. Results: Hyperglycemia and albuminuria were attenuated by EMPA. Renal mRNA expression for COX, PGE synthase, PGE2 (EP) receptor subtypes, CD AVP V2 receptors and aquaporin-2 was elevated in db/db mice, but unchanged by EMPA. Urine PGE2 levels increased in db/db but were unchanged by EMPA. AVP-water reabsorption was comparable in db/m and db/m+EMPA, and equally attenuated to 50% by PGE2. In db/db mice, AVP-water reabsorption was reduced by 50% compared to non-diabetic mice, and this reduction was unaffected by EMPA. In db/db mice, AVP-stimulated water transport was more significantly attenuated with PGE2 (62%), compared to non-diabetic mice, but this attenuation was reduced in response to EMPA, to 28%. Conclusion: In summary, expression of renal PGE2/EP receptors is increased in db/db mice, and this expression is unaffected by EMPA. However, in diabetic CD, PGE2 caused a greater attenuation in AVP-stimulated water reabsorption, and this attenuation is reduced by EMPA. This suggests that EMPA attenuates diabetes-induced excess CD water loss.

Localization of epithelial sodium channel subunit mRNAs in adult rat lung by in situ hybridization

1996 ◽  
Vol 271 (2) ◽  
pp. L332-L339 ◽  
Author(s):  
K. Matsushita ◽  
P. B. McCray ◽  
R. D. Sigmund ◽  
M. J. Welsh ◽  
J. B. Stokes
Keyword(s):  
In Situ Hybridization ◽  
Collecting Duct ◽  
Cortical Collecting Duct ◽  
Rat Lung ◽  
Pulmonary Epithelium ◽  
Adult Rat ◽  
Alveolar Level ◽  
Alpha Beta ◽  
Single Transcript

The transport of Na+ through amiloride-sensitive sodium channels (ENaC) plays a major role in the absorption of fluid across the pulmonary epithelium. The proteins forming the ENaC channel are encoded by three genes in the rat (alpha-, beta-, and gamma-rENaC). According to Northern blot, all three subunit mRNAs were expressed in adult rat lung. Each subunit was expressed as a single transcript of approximately 3.7, 2.2, and 3.2 kb for alpha-, beta-, and gamma-rENaC, respectively. To localize the alpha-, beta-, and gamma-rENaC subunit mRNAs, we used in situ hybridization. Frozen and paraffin-embedded tissues were hybridized with sense and antisense 35S-labeled riboprobes. The alpha-rENaC mRNA was most abundant and was expressed diffusely in epithelia of the trachea, bronchi, bronchioles, and alveoli. At the alveolar level, alpha-rENaC was expressed in type II cells. The beta- and gamma-rENaC mRNAs were most abundant in the bronchial and bronchiolar epithelia. All three subunits were expressed in the renal cortical collecting duct in a pattern similar to that previously reported by other investigators. Thus the rENaC subunit mRNAs are expressed in regions of the lung where functional Na+ absorption is found. These results are consistent with an important role for ENaC in the absorption of Na+ and fluid across the pulmonary epithelium in all regions of the lung.

Urinary concentrating function in mice lacking EP3 receptors for prostaglandin E2

1998 ◽  
Vol 275 (6) ◽  
pp. F955-F961 ◽  
Author(s):  
Eric F. Fleming ◽  
Krairek Athirakul ◽  
Michael I. Oliverio ◽  
Mikelle Key ◽  
Jennifer Goulet ◽  
...  
Keyword(s):  
Collecting Duct ◽  
Renal Medulla ◽  
Urine Osmolality ◽  
Receptor Subtypes ◽  
Cortical Collecting Duct ◽  
Prostanoid Production ◽  
Organ Systems ◽  
Ep Receptor ◽  
The Individual

The actions of prostaglandin (PG) E2 are mediated by four distinct classes of PGE2E-prostanoid (EP) receptors (EP1through EP4). However, the in vivo functions of the individual EP receptor subtypes have not been delineated. To study the functions of one of these subtypes, the EP3 receptor, we generated EP3-deficient (−/−) mice by gene targeting. EP3 −/− animals survived in expected numbers, reproduced, and had no obvious abnormalities in their major organ systems. Because the EP3 receptor is expressed at high levels in the renal medulla and cortical collecting duct, and because previous studies have suggested that the EP3 receptor might antagonize the effects of vasopressin in the distal nephron, we examined urinary concentrating functions in EP3−/− mice. Basal urine osmolality (UOsm) was similar in groups of EP3 −/− and wild-type (EP3 +/+) mice. However, after inhibition of endogenous PGE2 production by indomethacin, UOsm increased significantly in EP3 +/+ but not in EP3 −/− mice. Despite this insensitivity to acute inhibition of prostanoid production, EP3 −/− mice concentrated and diluted their urine normally in response to a series of physiological stimuli. This suggests that PGE2 acts through the EP3 receptor to modulate urinary concentrating mechanisms in the kidney, but these effects are not essential for normal regulation of urinary osmolality.

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.

Cortical collecting duct Na-K pump in obstructive nephropathy

1990 ◽  
Vol 258 (5) ◽  
pp. F1320-F1327 ◽  
Author(s):  
H. Kimura ◽  
S. K. Mujais
Keyword(s):  
Ureteral Obstruction ◽  
Turnover Rate ◽  
Collecting Duct ◽  
Obstructive Nephropathy ◽  
Cortical Collecting Duct ◽  
Sprague Dawley ◽  
Irreversible Damage ◽  
Sprague Dawley Rats ◽  
Collecting Tubule

The present study examined the alterations in the cortical collecting tubule (CCT) Na-K pump that occur after unilateral ureteral obstruction and their consequences on electrolyte excretion. In male Sprague-Dawley rats, unilateral ureteral ligation led to a progressive decrease in intact CCT Na-K pump in situ turnover worsening with the duration of the obstruction: control, 20.1 +/- 0.4; obstructed kidney: 3 h, 14.6 +/- 0.3; 12 h, 12.7 +/- 0.6; 24 h, 12.8 +/- 0.5; 48 h, 11.6 +/- 0.5; and 96 h, 10.6 +/- 0.4 pmol Rb.mm-1.min-1 (all P less than 0.001 vs. control). CCT diameter increased with the duration of obstruction. Release of ureteral obstruction was associated with restitution of pump turnover rate. With 3 h of obstruction, recovery of pump in situ turnover was complete (19.7 +/- 0.4 pmol Rb.mm-1.min-1) by 24 h after release. With more prolonged obstruction (24 h) recovery was partial by 24 h postrelease (16.2 +/- 0.5 pmol Rb.mm-1.min-1) and complete (19.8 +/- 0.7 pmol Rb.mm-1.min-1) by 48 h, suggesting a delay in recovery without the occurrence of irreversible damage. The impairment in Na-K pump in situ turnover was paralleled by an impairment in the ability of the obstructed kidney to excrete an acute potassium load. This parallelism of functional and biochemical studies favors the notion that impairment of CCT Na-K pump in situ turnover contributes significantly to the abnormal potassium excretion that accompanies obstructive damage.

Functional characterization of basolateral and luminal dopamine receptors in rabbit CCD

2001 ◽  
Vol 281 (1) ◽  
pp. F114-F122 ◽  
Author(s):  
Osamu Saito ◽  
Yasuhiro Ando ◽  
Eiji Kusano ◽  
Yasushi Asano
Keyword(s):  
Receptor Agonist ◽  
Collecting Duct ◽  
Functional Characterization ◽  
Receptor Subtypes ◽  
Cortical Collecting Duct ◽  
Basolateral Side ◽  
Skf 81297 ◽  
Transepithelial Voltage ◽  
Specific Antagonist

Previous studies reported the existence of both D1- and D2-like receptors in the cortical collecting duct (CCD). However, especially with regard to natriuresis, it remains controversial. In the present study, rabbit CCD was perfused to characterize the receptor subtypes responsible for the tubular actions. Basolateral dopamine (DA) induced a dose-dependent depolarization of transepithelial voltage. Basolateral domperidone, a D2-like receptor antagonist, abolished depolarization, whereas SKF-81297, a D1-like receptor agonist, showed no significant change. In addition, bromocriptine, a D2-like receptor agonist, also caused depolarization, whereas SKF-81297, a D1-like receptor agonist, did not depolarize significantly. Moreover, RBI-257, a D4-specific antagonist, reversed the basolateral DA-induced depolarization. In contrast to the basolateral side, luminal DA caused depolarization via a D1-like receptor; however the change was less than that for basolateral DA. For further evaluation, 22Na+ flux ( J Na) was measured to confirm the effect of DA on Na+ transport. Basolateral DA also caused a suppression of J Na, and this reaction was abolished by domperidone. These results suggested that the basolateral D2-like receptor is mainly responsible for the natriuretic action of DA in rabbit CCD.

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