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- Brismar, Hjalmar, et al.
(författare)
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beta-Adrenoceptor agonist sensitizes the dopamine-1 receptor in renal tubular cells
- 2002
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Ingår i: Acta Physiologica Scandinavica. - 0001-6772 .- 1365-201X. ; 175:4, s. 333-340
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Tidskriftsartikel (refereegranskat)abstract
- The renal effects of dopamine are mainly mediated via the dopamine-1 receptor (D1 receptor). This receptor is recruited from intracellular compartments to the plasma membrane by dopamine and atrial natriuretic peptide (ANP), via adenylyl cyclase activation. We have studied whether isoproterenol, a beta -adrenoceptor (beta -AR) agonist that may interact with dopamine in the regulation of rat renal Na+, K+ -adenosine triphosphatase (ATPase) activity, can recruit D1 receptors to the plasma membrane. The spatial regulation of D1 receptors was examined using confocal microscopy techniques in LLCPK cells and the functional interaction between dopamine and isoproterenol was examined by studying their effects on Na+, K+ -ATPase activity in microdissected single proximal tubular segments from rat. Isoproterenol was found to translocate the D1 receptors from the interior of the cell towards the plasma membrane. The recruitment of dopamine 1 receptors was found to be cyclic adenosine phosphate (cAMP) dependent, while protein kinase C (PKC) activation was not involved. The functional studies on Na+, K+ -ATPase activity showed that the effect of isoproterenol was abolished by a D1-like receptor antagonist (SCH 23390), and mediated via protein kinase A (PKA) and PKC dependent pathways. The results provide an explanation for the interaction between G protein-coupled receptors. The effects of isoproterenol on Na+, K+ -ATPase activity can be explained by a heterologous recruitment of D1 receptors to the plasma membrane.
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- Brismar, Hjalmar, et al.
(författare)
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Mechanisms by which intrarenal dopamine and ANP interact to regulate sodium metabolism
- 2000
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Ingår i: Clinical and experimental hypertension (1993, Print). - 1064-1963 .- 1525-6006. ; 22:3, s. 303-307
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Tidskriftsartikel (refereegranskat)abstract
- Maintenance of a normal blood pressure requires a precise and fine-tuned regulation of salt metabolism. This is accomplished by a bidirectional regulation of renal tubular sodium transporters by natriuretic and antinatriuretic hormones. Dopamine, produced in the renal proximal tubular cells, plays an important role in this interactive system. Dopamine inhibits the activity of Na+,K(+)ATPase as well as of many important sodium influx pathways in the nephron. These effects of dopamine are particularly pronounced in situation of sodium loading. There is an abundance of evidence suggesting that the natriuretic effects of ANP are to a large extent mediated via renal dopamine 1 like receptors. The renal tubular dopamine 1 like receptors are, under basal conditions, mainly located intracellularly. ANP and its second messenger, cGMP, cause a rapid translocation of the dopamine 1 like receptors to the plasma membrane. This phenomenon may explain how ANP and dopamine act in concert to regulate sodium metabolism Regulation of sodium metabolism and blood pressure is critically dependent on a normal function of the renal dopamine system. Hence, abnormalities in the interaction between dopamine and ANP may predispose to hypertension.
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- Brismar, Hjalmar, et al.
(författare)
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The role of endocytosis in renal dopamine D1 receptor signaling
- 2006
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Ingår i: Pflügers Archiv. - : Springer Science and Business Media LLC. - 0031-6768 .- 1432-2013. ; 451:6, s. 793-802
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Tidskriftsartikel (refereegranskat)abstract
- Desensitization of G-protein-coupled receptors (GPCR) includes receptor endocytosis. This phenomenon is suggested, at least for some receptors, to be associated with receptor resensitization. Here, we examined the role of receptor endocytosis for two different GPCR, the dopamine-1 (D1) receptor and the beta 1-adrenoceptor (beta(1)-AR) in renal tissue. The functional role of receptor endocytosis was examined on Na+, K+-ATPase activity in microdissected proximal tubules from rat kidney. The spatial regulation of endogenous D1 receptors and beta(1)-AR was examined by confocal microscopy techniques in LLCPK cells. Phenylarsine oxide (PAO) an endocytosis inhibitor, attenuated isoproterenol-induced decrease in Na+, K+-ATPase activity but had no such effect on dopamine-induced decrease in Na+, K+-ATPase activity. We have previously shown that isoproterenol sensitizes the renal dopamine system, by recruiting silent D1 receptors from the interior of the cell towards the plasma membrane. This effect was attenuated by PAO as well as by cytochalasin D while these substances had no effect on dopamine-induced D1 receptor recruitment. The beta(1)-AR was localized to the plasma membrane in control cells. Isoproterenol induced a rapid internalization of the beta(1)-AR; which was prevented by PAO. The results suggest that endocytosis of beta(1)-AR in renal proximal tubular cells is an important step in signal generation, while endocytosis of proximal tubular D1 receptor is not.
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- Crambert, S, et al.
(författare)
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Prolactin and dopamine 1-like receptor interaction in renal proximal tubular cells
- 2010
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Ingår i: American journal of physiology. Renal physiology. - : American Physiological Society. - 1522-1466 .- 1931-857X. ; 299:1, s. F49-F54
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Tidskriftsartikel (refereegranskat)abstract
- Prolactin is a natriuretic hormone and acts by inhibiting the activity of renal tubular Na+-K+-ATPase activity. These effects require an intact renal dopamine system. Here, we have studied by which mechanism prolactin and dopamine interact in Sprague-Dawley rat renal tissue. Na+-K+-ATPase activity was measured as ouabain-sensitive ATP hydrolysis in microdissected renal proximal tubular segments. Intracellular signaling pathways were studied by a variety of different techniques, including Western blotting using phosphospecific antibodies, immunoprecipitation, and biotinylation assays. We found that dopamine and prolactin regulated Na+-K+-ATPase activity via similar signaling pathways, including protein kinase A, protein kinase C, and phosphoinositide 3-kinase activation. The cross talk between prolactin and dopamine 1-like receptors was explained by a heterologous recruitment of dopamine 1-like receptors to the plasma membrane in renal proximal tubular cells. Prolactin had no effect on Na+-K+-ATPase activity in spontaneously hypertensive rats, a rat strain with a blunted response to dopamine. These results further emphasize the central role of the renal dopamine system in the interactive regulation of renal tubular salt balance.
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- Holtback, U., et al.
(författare)
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Intrarenal dopamine coordinates the effect of antinatriuretic and natriuretic factors
- 2000
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Ingår i: Acta Physiologica Scandinavica. - : Wiley. - 0001-6772 .- 1365-201X. ; 168:1, s. 215-218
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Tidskriftsartikel (refereegranskat)abstract
- The precision by which sodium balance is regulated suggests an intricate interaction between modulatory factors released from intra- and extrarenal sources. Intrarenally produced dopamine has a central role in this interactive network. Dopamine, produced in renal tubular cells acts as an autocrine and paracrine factor to inhibit the activity of Na+,K+-ATPase as well as of a number of sodium influx pathways. The natriuretic effect of dopamine is most prominent under high salt diet. The antinatriuretic effects of noradrenaline, acting on alpha-adrenoceptors and angiotensin II are opposed by dopamine as well as by atrial natriuretic peptide (ANP). Several lines of evidence have suggested that ANP acts via the renal dopamine system and recent studies from our laboratory have shown that this effect is attributed to recruitment of silent D1 receptors from the interior of the cell towards the plasma membrane. Taken together, the observations suggest that dopamine coordinates the effects of antinatriuretic and natriuretic factors and indicate that an intact renal dopamine system is of major importance for the maintenance of sodium homeostasis and normal blood pressure.
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- Khan, F, et al.
(författare)
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Negative reciprocity between angiotensin II type 1 and dopamine D1 receptors in rat renal proximal tubule cells
- 2008
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Ingår i: American journal of physiology. Renal physiology. - : American Physiological Society. - 1931-857X .- 1522-1466. ; 295:4, s. F1110-F1116
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Tidskriftsartikel (refereegranskat)abstract
- Sodium excretion is bidirectionally regulated by dopamine, acting on D1-like receptors (D1R) and angiotensin II, acting on AT1 receptors (AT1R). Since sodium excretion has to be regulated with great precision within a short frame of time, we tested the short-term effects of agonist binding on the function of the reciprocal receptor within the D1R-AT1R complex in renal proximal tubule cells. Exposure of rat renal proximal tubule cells to a D1 agonist was found to result in a rapid partial internalization of AT1R and complete abolishment of AT1R signaling. Similarly, exposure of rat proximal tubule cells and renal tissue to angiotensin II resulted in a rapid partial internalization of D1R and abolishment of D1R signaling. D1R and AT1R were, by use of coimmunoprecipitation studies and glutathione- S-transferase pull-down assays, shown to be partners in a multiprotein complex. Na+-K+-ATPase, the target for both receptors, was included in this complex, and a region in the COOH-terminal tail of D1R (residues 397-416) was found to interact with both AT1R and Na+-K+-ATPase. Results indicate that AT1R and D1R function as a unit of opposites, which should provide a highly versatile and sensitive system for short-term regulation of sodium excretion.
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| 22. |
- Kruse, M. S., et al.
(författare)
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Recruitment of renal dopamine 1 receptors requires an intact microtubulin network
- 2003
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Ingår i: Pflügers Archiv. - : Springer Science and Business Media LLC. - 0031-6768 .- 1432-2013. ; 445:5, s. 534-539
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Tidskriftsartikel (refereegranskat)abstract
- Renal dopamine1 receptor (D1R) can be recruited from intracellular compartments to the plasma membrane by D1R agonists and endogenous dopamine. This study examines the role of the cytoskeleton for renal D1R recruitment. The studies were performed in LLCPK-1 cells that have the capacity to form dopamine from L-dopa. In approximately 50% of the cells treated with L-dopa the D1R was found to be translocated from intracellular compartments towards the plasma membrane. Disruption of the microtubulin network by noco-dazole significantly prevented translocation. In contrast, depolymerization of actin had no effect. In control cells D1R colocalized with NBD-C-6-ceramide, a trans-Golgi fluorescent marker. This colocalization was disrupted in L-dopa-treated cells. Tetanus toxin, an inhibitor of exocytosis, prevented L-dopa-induced receptor recruitment. L-Dopa treatment resulted in activation of protein kinase C (PKC). To test the functional effect of D1R recruitment, the capacity of D1R agonists to activate PKC was studied. Activation of D1R significantly translocated PKC-alpha from intracellular compartments to the plasma membrane. Disruption of microtubules abolished D1R-mediated - but not phorbol-ester-mediated - translocation of PKC. We conclude that renal D1R recruitment requires an intact microtubulin network and occurs via Golgi-derived vesicles. These newly recruited receptors couple to the PKC signaling pathway.
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