Lack of effect of atrial natriuretic peptide and urodilatin on vasopressin-stimulated cyclic AMP production in microdissected rat inner medullary collecting ducts

1994 ◽  
Vol 12 (2) ◽  
pp. 149-154
Author(s):  
W J Burgess ◽  
M N Perrott ◽  
R J Balment

ABSTRACT It is unclear whether the diuretic effects of atrial natriuretic peptide (ANP) result, in part, from an inhibition of the renal actions of vasopressin. Moreover, accruing evidence suggests that the kidneys themselves may produce an ANP-like peptide, urodilatin, which shares many of the renal actions of ANP. The mechanism underlying the diuretic action of urodilatin has not yet been examined. Accordingly, we have investigated the potential modulatory actions of both ANP and urodilatin on vasopressin-stimulated cyclic AMP (cAMP) production in microdissected inner medullary collecting duct (IMCD) segments of rat kidney. ANP and urodilatin alone (at 10−8 or 10−6 m) had no demonstrable effect on cAMP accumulation in IMCD segments. Moreover, neither ANP nor urodilatin (each at 10−6 m) significantly altered either the profile or the absolute magnitude of the cAMP response stimulated by vasopressin. These findings indicate that neither ANP nor urodilatin interacts with the vasopressin-sensitive adenylate cyclase site in the rat IMCD to contribute to its diuretic actions.

2009 ◽  
Vol 297 (3) ◽  
pp. F693-F703 ◽  
Author(s):  
Jens Klokkers ◽  
Patrik Langehanenberg ◽  
Björn Kemper ◽  
Sebastian Kosmeier ◽  
Gert von Bally ◽  
...  

AVP and atrial natriuretic peptide (ANP) have opposite effects in the kidney. AVP induces antidiuresis by insertion of aquaporin-2 (AQP2) water channels into the plasma membrane of collecting duct principal cells. ANP acts as a diuretic factor. An ANP- and nitric oxide (NO)/soluble guanylate cyclase (sGC)-induced insertion of AQP2 into the plasma membrane is reported from different models. However, functional data on the insertion of AQP2 is missing. We used primary cultured inner medullary collecting duct (IMCD) cells and digital holographic microscopy, calcein-quenching measurements, and immunofluorescence and Western blotting to analyze the effects of ANP and NO donors on AQP2 phosphorylation, membrane expression, and water permeability. While AVP led to acceleration in osmotically induced swelling, ANP had no effect. However, in AVP-pretreated cells ANP significantly decreased the kinetics of cell swelling. This effect was mimicked by 8-bromo-cGMP and blunted by PKG inhibition. Stimulation of the NO/sGC pathway or direct activation of sGC with BAY 58-2667 had similar effects to ANP. In cells treated with AVP, AQP2 was predominantly localized in the plasma membrane, and after additional incubation with ANP AQP2 was mostly localized in the cytosol, indicating an increased retrieval of AQP2 from the plasma membrane by ANP. Western blot analysis showed that ANP was able to reduce AVP-induced phosphorylation of AQP2 at position S256. In conclusion, we show that the diuretic action of ANP or NO in the IMCD involves a decreased localization of AQP2 in the plasma membrane which is mediated by cGMP and PKG.


1992 ◽  
Vol 70 (8) ◽  
pp. 1167-1174 ◽  
Author(s):  
Peter Cernacek ◽  
Louis Legault ◽  
Duncan J. Stewart ◽  
Mortimer Levy

The diverse biological actions of endothelins (ET) appear to be mediated by specific cell-surface receptors. Autoradiography and membrane binding studies have shown abundant ET binding sites in the kidney. However, their expression in specific types of renal cells is unclear. We studied the binding of 125I-labelled endothelin-1 in freshly isolated cell suspensions from canine inner medullary collecting duct. Competition binding experiments revealed the presence of specific high-affinity binding sites: unlabelled ET-1 and ET-2 competed with the radioligand with an IC50 of 135 and 83 pM, respectively, while the IC50 of ET-3 and big ET-1 were 2 and 4 orders of magnitude higher, indicating the presence of ETA-type receptor. Angiotensin II, vasopressin, and atrial natriuretic peptide (ANP) did not compete for ET binding even at a concentration of 10−6 M. Saturation binding experiments showed a single class of binding sites of high density (Bmax = 56.7 ± 10.3 fmol/106 cells) and high affinity (Kd = 69.8 ± 10 pM). In contrast, ANP receptors in the same cell preparations appeared as two classes of binding sites with widely different affinity and density. The high-affinity ANP site (Kd = 311 ± 48 pM) was compatible with ANP-B (guanylate cyclase-coupled) receptor. ET-1 did not compete for this receptor. ET-1 (10−7 M) did not alter ANP-induced cGMP generation in these cells (3.8-fold increase at 10−7 M ANP), nor basal levels of cGMP. The expression by the distal tubular epithelium of specific ET-1 binding sites strongly suggests the presence of a functional receptor, which may mediate the inhibition of Na+ transport in these cells. The mechanism and the transduction pathway of this effect appear to be different and independent from those of ANP.Key words: endothelin receptor, distal collecting duct, atrial natriuretic peptide receptor, cGMP generation.


1986 ◽  
Vol 136 (3) ◽  
pp. 947-954 ◽  
Author(s):  
Shigeyuki Takeda ◽  
Eiji Kusano ◽  
Naoki Murayama ◽  
Yasushi Asano ◽  
Saichi Hosoda ◽  
...  

1993 ◽  
Vol 71 (2) ◽  
pp. 157-164 ◽  
Author(s):  
Louis Legault ◽  
Leonard C. Warner ◽  
Wai Ming Leung ◽  
Alexander G. Logan ◽  
Laurence M. Blendis ◽  
...  

The nature of sodium retention in cirrhosis complicated by ascites has been studied for the last 30 years. Resistance to the natriuretic action of atrial natriuretic peptide (ANP) may play a potential role in this sodium retention. To further evaluate this possibility, we studied 12 patients with biopsy-proven cirrhosis and ascites on 2 consecutive days after a 7-day period off diuretics while receiving a 20 mmol/day sodium restricted diet. Following a crossover design, patients underwent head-out water immersion (HWI) for 3 h and were infused with a α-human ANP for 2 h on 2 consecutive days. Blood and urine samples were collected hourly. Five patients displayed a natriuretic response to HWI, sufficient to achieve negative sodium balance, and these patients were termed responders. Each of these five patients also displayed a natriuretic response to ANP infusion. In contrast, the other seven patients (nonresponders) consistently failed to develop a natriuretic response to either maneuver. The two groups had similar elevations in plasma ANP concentrations, but at baseline differed in terms of plasma sodium, plasma renin activity, and serum aldosterone. Despite higher serum aldosterone concentrations, nonresponders excreted less potassium than responders during the peak effect of the interventions, suggesting greater sodium delivery to the aldosterone-sensitive nephron segment in responders. We conclude that the inability to mount an adequate sodium excretory response to HWI in patients with cirrhosis may be conveyed through increased antinatriuretic factors that decrease the sodium delivery to the medullary collecting duct and inhibit the natriuretic effect of ANP at that site.Key words: atrial natriuretic peptide, cirrhosis, ascites, sodium.


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