Effect of cAMP on prostaglandin E2 production in cultured rat inner medullary collecting tubule cells

1986 ◽  
Vol 251 (4) ◽  
pp. F671-F677 ◽  
Author(s):  
I. Teitelbaum ◽  
J. N. Mansour ◽  
T. Berl
Keyword(s):  
Arachidonic Acid ◽  
Collecting Duct ◽  
Feedback System ◽  
Ionophore A23187 ◽  
Homogeneous Population ◽  
Pge2 Synthesis ◽  
Collecting Tubule ◽  
Collecting Duct Cells ◽  
Medullary Collecting Duct ◽  
Pg E2

Studies were performed to determine whether cAMP impairs prostaglandin (PG) E2 production in a homogeneous population of cultured rat inner medullary collecting duct cells. Three structurally different cAMP analogues were shown to decrease PGE2 synthesis by 48.4% in the basal state and by 49.3% in response to the divalent cation ionophore A23187 (5 microM). Thromboxane B2 production was similarly suppressed. An increase in endogenous cAMP by forskolin also decreased PGE2 synthesis. To determine the locus of the cAMP effect we examined the response to exogenously added arachidonic acid. At a concentration of arachidonic acid (5 micrograms/ml) sufficient to render the phospholipase-dependent fraction negligible (as evidenced by the lack of a mepacrine effect), cAMP had no effect on PGE2 production, suggesting phospholipase as the site of cAMP action. Further evidence for a phospholipase-mediated mechanism derives from studies employing [5,6,8,9,11,12,14,15-3H(N)]arachidonic acid in which cAMP analogues had no effect on the rate of cellular arachidonic acid incorporation, but did impair the release of tritiated arachidonic acid in response to ionophore. These results suggest the existence of a negative feedback system that, by impairing phospholipase activity and PGE2 synthesis, could enhance the action of cAMP in the antidiuretic state.

Effects of prostacyclin on the cAMP system in cultured rat inner medullary collecting duct cells

1990 ◽  
Vol 258 (5) ◽  
pp. F1218-F1223 ◽  
Author(s):  
J. H. Veis ◽  
M. A. Dillingham ◽  
T. Berl
Keyword(s):  
Collecting Duct ◽  
Collecting Tubule ◽  
Collecting Duct Cells ◽  
Medullary Collecting Duct ◽  
Camp System ◽  
Pge2 Receptor ◽  
Collecting Tubules ◽  
Sites Of Action ◽  
Dose Dependent Increase ◽  
Dose Dependent

Rat inner medullary collecting tubule (RIMCT) cells produce arachidonate derivatives including prostacyclin (PGI2). In RIMCT cells, PGI2 causes a dose-dependent increase in adenosine 3',5'-cyclic monophosphate (cAMP; fmol/micrograms protein) from a basal level of 15.6 +/- 1.7 to 32.4 +/- 5.7 at 0.3 microM, 63.3 +/- 8.3 at 3 microM, and 103.5 +/- 9.4 at 30 microM PGI2. At concentrations of arginine vasopressin (AVP) from 10(-7) to 10(-9) M, cAMP was greater in the presence than absence of 3 microM PGI2, suggesting independent sites of action. To assess whether the PGI2 effect is mediated by the prostaglandin E2 (PGE2) receptor, desensitization studies were performed. A 6-h preincubation with 10 microM PGE2 blunted the response to 3 microM PGE2 by 90 +/- 2% but the PGI2 response was decreased by only 31 +/- 5%, P less than 0.001. Carbaprostacyclin (carba-PGI2), a stable analogue of PGI2, blunted the cAMP response to PGI2 by 94 +/- 3% but to PGE2 by only 46 +/- 7%, P less than 0.005. The postreceptor effect of PGI2 on components of the adenylate cyclase was examined. The response to forskolin was markedly potentiated by PGI2. PGI2 (3 microM) caused an increase in cAMP of 67 fmol/micrograms over basal in the absence of forskolin, of 164 fmol/micrograms at 10(-7) M forskolin, of 386 fmol/micrograms at 10(-6) M forskolin, and of 563 fmol/micrograms at 10(-5) M forskolin. The response of PGI2 was likewise potentiated by forskolin. Water permeability alone or in response to AVP in isolated perfused inner medullary collecting tubules was not affected by carba-PGI2.(ABSTRACT TRUNCATED AT 250 WORDS)

Determination of prostaglandin E2 synthesis along rabbit nephron by enzyme immunoassay

1986 ◽  
Vol 251 (2) ◽  
pp. F238-F244 ◽  
Author(s):  
N. Farman ◽  
P. Pradelles ◽  
J. P. Bonvalet
Keyword(s):  
Arachidonic Acid ◽  
Prostaglandin E2 ◽  
Enzyme Immunoassay ◽  
Collecting Duct ◽  
Distal Tubule ◽  
Rabbit Kidney ◽  
Thick Ascending Limb ◽  
Pge2 Synthesis ◽  
Collecting Tubule ◽  
Cortical Collecting Tubule

Prostaglandin E2 (PGE2) content and synthesis have been measured in microdissected segments from the entire nephron of rabbit kidney. PGE2 was determined by an enzyme immunoassay on glomeruli or tubular segments (0.5-5 mm) either immediately after microdissection (PGE2 content) or after incubation for 15 min at 37 degrees C in the presence of arachidonic acid (PGE2 synthesis). We confirmed that collagenase used for microdissection did not modify PGE2 synthesis. A linear correlation was found between the length of tubule used in the assay and PGE2 synthesis, as well as between incubation time with arachidonic acid and PGE2 synthesis. PGE2 synthesis, expressed in picograms per millimeter tubular length per 15 min, was maximum in medullary collecting duct (517 +/- 73). High values were also found in the granular portion of distal tubule (134 +/- 22) and granular or light portion of cortical collecting tubule (199 +/- 24 and 146 +/- 10, respectively). Synthesis was lower in all other segments: 17 +/- 6 and 24 +/- 12, respectively, in convoluted and straight proximal tubule, 67 +/- 12 and 71 +/- 5, respectively, in thin descending and ascending limb, 51 +/- 9 and 23 +/- 4, respectively, in medullary and cortical thick ascending limb of Henle's loop, and 25 +/- 7 in initial distal tubule. Synthesis per glomerulus was 24 +/- 3. When the protein content of each nephron segment is taken into account, this profile was not modified, except for the thin limbs of the loop, which reached values per nanogram protein slightly higher than those of the cortical collecting tubule.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Anti-Malignant Ascites Effect of Total Diterpenoids from Euphorbiae ebracteolatae Radix Is Attributable to Alterations of Aquaporins via Inhibiting PKC Activity in the Kidney

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 942
Author(s):  
Yuanbin Zhang ◽  
Dongfang Liu ◽  
Fan Xue ◽  
Hongli Yu ◽  
Hao Wu ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Antitumor Activity ◽  
Membrane Fraction ◽  
Collecting Duct ◽  
Human Kidney ◽  
Underlying Mechanism ◽  
Malignant Ascites ◽  
Kinase C ◽  
Collecting Duct Cells ◽  
Medullary Collecting Duct

This study evaluated the anti-ascites effect of total diterpenoids extracted from Euphorbiae ebracteolatae Radix (TDEE) on malignant ascitic mice and elucidated its underlying mechanism. TDEE was extracted by dichloromethane and subjected to column chromatography. The purity of six diterpenoids isolated from TDEE was determined to be 77.18% by HPLC. TDEE (3 and 0.6 g raw herbs/kg, p.o.) reduced ascites and increased urine output. Meanwhile, analysis of tumor cell viability, cycle and apoptosis indicated that TDEE had no antitumor activity. In addition, the expression levels of aquaporins (AQPs) and the membrane translocation levels of protein kinase C (PKC) α and PKCβ in kidney and cells were measured. TDEE reduced the levels of AQP1–4, and inhibited PKCβ expression in membrane fraction. Four main diterpenoids, except compound 2, reduced AQP1 level in human kidney-2 cells. Compounds 4 and 5 inhibited AQP2–4 expression in murine inner medullary collecting duct cells. The diterpenoid-induced inhibition of AQP1–4 expression was blocked by phorbol-12-myristate-13-acetate (PMA; agonist of PKC). The diterpenoids from TDEE are the main anti-ascites components. The anti-ascites effect of diterpenoids may be associated with alterations in AQPs in the kidneys to promote diuresis. The inhibition of AQP1–4 expression by TDEE is related to the inhibition of PKCβ activation.

Ultramicrodetermination of vasopressin-regulated urea transporter protein in microdissected renal tubules

1997 ◽  
Vol 272 (4) ◽  
pp. F531-F537 ◽  
Author(s):  
B. K. Kishore ◽  
J. Terris ◽  
P. Fernandez-Llama ◽  
M. A. Knepper
Keyword(s):  
Collecting Duct ◽  
Enzyme Linked Immunosorbent Assay ◽  
Apical Plasma Membrane ◽  
Renal Tubules ◽  
Urea Transport ◽  
Urea Transporter ◽  
Transporter Protein ◽  
Low Protein ◽  
Collecting Duct Cells ◽  
Medullary Collecting Duct

The vasopressin-regulated urea transporter (VRUT) is a 97-kDa protein (also called “UT-1”) responsible for facilitated urea transport across the apical plasma membrane of inner medullary collecting duct (IMCD) cells. To determine the abundance of VRUT protein in collecting duct cells of the rat, we designed a sensitive fluorescence-based enzyme-linked immunosorbent assay capable of detecting <5 fmol of VRUT protein. In collecting duct segments, measurable VRUT was found in microdissected IMCD segments but not in other portions of the collecting duct. In the mid-IMCD, the measured level averaged 5.3 fmol/mm tubule length, corresponding to approximately 5 million copies of VRUT per cell. Thus VRUT is extremely abundant in the IMCD, accounting, in part, for the extremely high urea permeability of this segment. Feeding a low-protein diet (8% protein) markedly decreased urea clearance but did not alter the quantity of VRUT protein in the IMCD. Thus increased urea transport across the collecting duct with dietary protein restriction is not a consequence of increased expression of VRUT. Based on urea fluxes measured in the IMCD and our measurements of the number of copies of VRUT, we estimate a turnover number of > or = 0.3-1 x 10(5) s. In view of the large magnitude of this value and previously reported biophysical properties of urea transport in collecting ducts, we hypothesize that the VRUT may function as a channel rather than a carrier.

Urodilatin: binding properties and stimulation of cGMP generation in rat kidney cells

1993 ◽  
Vol 264 (2) ◽  
pp. F267-F273
Author(s):  
H. Saxenhofer ◽  
W. R. Fitzgibbon ◽  
R. V. Paul
Keyword(s):  
Guanylate Cyclase ◽  
Mesangial Cells ◽  
Collecting Duct ◽  
Rat Kidney ◽  
Binding Characteristics ◽  
Papillary Collecting Duct ◽  
Collecting Duct Cells ◽  
Medullary Collecting Duct ◽  
Anp Receptors

Urodilatin (URO) [ANP-(95-126)] is an analogue of atrial natriuretic peptide (alpha-ANP) [ANP-(99-126)] that was first isolated from human urine. In rat mesangial cells, URO competed with high affinity for non-guanylate cyclase-coupled ANPR-C receptors [concentration at which 50% labeled ligand is displaced (IC50) approximately 70 pM], but with lesser affinity to the guanylate cyclase-linked ANPR-A receptors (IC50 approximately 800 pM). alpha-ANP bound to both receptors with similar affinity [dissociation constant (Kd) approximately 150 pM]. In papillary collecting duct homogenates, which possess only ANPR-A receptors, the apparent Kd value averaged 229 pM for alpha-ANP and 2.7 nM for URO. Intravenous URO was at least as potent and effective as alpha-ANP in inducing diuresis and natriuresis in anesthetized rats, but URO was approximately 10-fold less potent in stimulating guanosine 3',5'-cyclic monophosphate generation in mesangial and inner medullary collecting duct cells. We conclude that URO has a lesser affinity than alpha-ANP for guanylate cyclase-coupled ANP receptors in the kidney and that the relative natriuretic potency of URO in vivo cannot be directly attributed to its binding characteristics with ANPR-A receptors.

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