Fluid homeostasis, blood pressure and redox balance in the kidney are regulated by an intricate interaction between local and systemic anti-natriuretic and natriuretic systems. Intrarenal dopamine plays a central role on this interactive network. By activating specific receptors, dopamine promotes sodium excretion and stimulates anti-oxidant and anti-inflammatory pathways. Different pathological scenarios where renal sodium excretion is dysregulated, as in nephrotic syndrome, hypertension and renal inflammation, can be associated with impaired action of renal dopamine including alteration in biosynthesis, dopamine receptor expression and signal transduction. Given its properties on the regulation of renal blood flow and sodium excretion, exogenous dopamine has been postulated as a potential therapeutic strategy to prevent renal failure in critically ill patients. The aim of this review is to update and discuss on the most recent findings about renal dopaminergic system and its role in several diseases involving the kidneys and the potential use of dopamine as a nephroprotective agent.

J. Neurochem. (2012) 120, 46–55. Abstract As angiotensin (Ang) (1–7) decreases norepinephrine (NE) content in the synaptic cleft, we investigated the effect of Ang‐(1–7) on NE neuronal uptake in spontaneously hypertensive rats. [3H]‐NE neuronal uptake was measured in isolated hypothalami. NE transporter (NET) expression was evaluated in hypothalamic neuronal cultures by western‐blot. Ang‐(1–7) lacked an acute effect on neuronal NE uptake. Conversely, Ang‐(1–7) caused an increase in NET expression after 3 h incubation (40 ± 7%), which was blocked by the Mas receptor antagonist, a PI3‐kinase inhibitor or a MEK1/2 inhibitor suggesting the involvement of Mas receptor and the PI3‐kinase/Akt and MEK1/2‐ERK1/2 pathways in the Ang‐(1–7)‐stimulated NET expression. Ang‐(1–7) through Mas receptors stimulated Akt and ERK1/2 activities in spontaneously hypertensive rat neurons. Cycloheximide attenuated Ang‐(1–7) stimulation of NET expression suggesting that Ang‐(1–7) stimulates NET synthesis. In fact, Ang‐(1–7) increased NET mRNA levels. Thus, we evaluated the long‐term effect of Ang‐(1–7) on neuronal NE uptake after 3 h incubation. Under this condition, Ang‐(1–7) increased neuronal NE uptake by 60 ± 14% which was blocked by cycloheximide and the Mas receptor antagonist. Neuronal NE uptake and NET expression were decreased after 3 h incubation with an anti‐Ang‐(1–7) antibody. Ang‐(1–7) induces a chronic stimulatory effect on NET expression. In this way, Ang‐(1–7) may regulate a pre‐synaptic mechanism in maintaining appropriate synaptic NE levels during hypertensive conditions.

1.-- In the rat, a fructose-enriched diet induces hyperglycaemia, hypertriglyceridaemia, insulin resistance and hypertension; a model which resembles the human metabolic syndrome. 2.-- Prostanoids, metabolites of arachidonic acid, include vasoactive substances synthesized and released from the vascular wall that have been implicated in the increase of peripheral resistance, one of the mechanisms involved in the fructose-induced hypertension. 3.-- The aim of the present study was to: (i) analyse the effects of the in vitro incubation with fructose on the production and release of prostanoids in rat thoracic aorta and in rat mesenteric bed and (ii) compare the effects of incubation with those of the in vivo acute and chronic treatment of rats with fructose and with the combination of both in vivo and in vitro procedures. 4.-- Blood pressure, glycaemia and triglyceridaemia were significantly elevated in both 4- and 22-week fructose-treated groups. Meanwhile, body and heart weight as well as insulinaemia were similar between experimental animals and controls. 5.-- In aortae, 4 weeks of Fructose treatment did not modify the prostanoid pattern release, but in vitro incubation decreased prostacyclin (PGI(2)) production. However, after 22 weeks, fructose treatment and incubation exerted the same effect. 6.-- In mesenteric bed, after 4 weeks, the incubation and the combination of both procedures reduced the release of the vasodilators PGI(2) and PGE(2), while fructose treatment only diminished the PGE(2) release. On the contrary, the production of the vasoconstrictor thromboxane A(2) (TXA(2)) was enhanced by incubation and both the procedures. After 22 weeks, fructose treatment increased PGI(2) release, while it was reduced by incubation. The combination of both did not modify this peripheral resistance when compared with controls. Finally, incubation of tissues from treated rats increased the release of the vasoconstrictors, PGF(2alpha) and TXA(2). 7.-- In conclusion, the mesenteric bed, a resistance vascular bed, seems to be more sensitive than the aorta, a conductance vessel, to the effects of fructose on prostanoid production. This difference could be related to a more relevant role of resistance vessels in the regulation of peripheral resistance and consequently of blood pressure. The observed effects should contribute to a shift in the balance of the release of prostanoid in favour of vasoconstrictor metabolites. This phenomenon could be related to an increase in the peripheral resistance and the mild hypertension observed in the fructose-treated rats.