RESUMO
BACKGROUND: Considering long-term changes in renal sodium handling and blood pressure in maternal protein-restricted (LP) offspring, we assumed that the development of LP hypertension results from abnormal dorsal root ganglia (DRG) neurokinin expression associated with impaired responsiveness of renal sensory receptors, promoting a reduced urinary excretion of sodium. The present study investigates whether increased blood pressure in protein-restricted offspring would be associated with changes in the DRG cells and in renal pelvic wall expression of NK1R, SP and CGRP when compared to NP offspring. In addition, we assessed the tubular sodium handling, estimated by creatinine and lithium clearances before and after bilateral renal denervation in conscious LP offspring relative to age-matched NP counterparts. METHODS: Dams received a normal (NP) or low-protein diet (LP) during their entire pregnancy period. Male NP or LP offspring underwent bilateral surgical renal denervation before the 8-week renal functional test and blood pressure measurements. Immunofluorescence staining in DRG cells was assessed in optical sections by confocal laser scanning microscope. RESULTS: The current data demonstrated a sustained rise in blood pressure associated with a decrease in fractional excretion of sodium (FENa) by reducing post-proximal tubule sodium rejection in 16-wk old LP rats relative to age-matched NP counterparts. According to this study, bilateral renal denervation attenuated blood pressure and increased FENa in LP offspring. Furthermore, an immunohistochemical analysis showed a reduced expression of SP and CGRP in DRGs of LP when compared with NP rats. Renal pelvis of LP rats did not show a strong CGRP expression related to NP rats, whereas there was no change in SP immunostaining. CONCLUSIONS: These observations raise the possibility that impaired DRG and pelvic neurokinin expression associated with responsiveness of renal sensory receptors in 16-wk old LP offspring are conducive to excess renal reabsorption of sodium and development of hypertension in this programmed model.
Assuntos
Pressão Sanguínea/fisiologia , Dieta com Restrição de Proteínas , Gânglios Espinais/metabolismo , Pelve Renal/metabolismo , Neurocinina A/metabolismo , Sódio/metabolismo , Animais , Peptídeo Relacionado com Gene de Calcitonina/genética , Peptídeo Relacionado com Gene de Calcitonina/metabolismo , Catecolaminas/análise , Creatinina/metabolismo , Feminino , Rim/fisiologia , Lítio/análise , Lítio/metabolismo , Masculino , Microscopia de Fluorescência , Neurocinina A/genética , Potássio/análise , Ratos , Ratos Wistar , Sódio/análise , Substância P/genética , Substância P/metabolismoRESUMO
Phospholipid content and metabolism were studied in rat renal papillary, medullary and cortical slices. The highest concentration of phospholipids was found in cortex and the lowest in papilla samples (ratio cortex/medulla, 1.3; cortex/papilla, 3.7). The profile of the various phospholipids was different depending on the zone. The most important difference was the relative concentrations of sphingomyelin (CerPCho) and phosphatidylinositol (PtdIns) with ratios for PtdIns/CerPCho of 5.0, 3.3 and 2.5 in papilla, medulla, and cortex, respectively. In the three zones, PtdIns showed the highest specific activity for [2-14C]glycerol and [1-14C]arachidonic acid incorporation. By contrast, a higher amount of [1-14C]palmitic acid was incorporated into phosphatidylcholine than into any other phospholipid. The various radioactive precursors were only poorly incorporated into phosphatidylethanolamine. No radioactivity was associated with phosphatidylserine. The papilla possesses the most active phospholipid metabolism of all the pathways studied.
Assuntos
Ácidos Graxos/metabolismo , Rim/metabolismo , Fosfolipídeos/metabolismo , Animais , Ácido Araquidônico/metabolismo , Técnicas In Vitro , Rim/química , Córtex Renal/química , Córtex Renal/metabolismo , Medula Renal/química , Medula Renal/metabolismo , Pelve Renal/química , Pelve Renal/metabolismo , Masculino , Ácido Palmítico , Ácidos Palmíticos/metabolismo , Fosfolipídeos/análise , Ratos , Ratos Endogâmicos , Distribuição TecidualRESUMO
In order to study the role of the renal pelvis on urea sparing in sheep fed low protein diets, the pelvis was perfused through the ureter with 1M and 3M urea solutions. Eight ewes were used: four on a regular diet (total nitrogen 188.7 g.kg-1 dry matter) and the other four on a low protein diet (total nitrogen 109.4 g.kg-1 dry matter). On each animal, perfusions were performed on one kidney; the other one was kept as a control. Fractional excretion of urea (TEu) and urea (Cu), inulin, para-aminohippurate and osmolar clearances, were determined during five experimental periods of 30 min each (T = control, 1M = perfusion with 1M urea solution, R1 = first period of recovery, 3M = perfusion with 3M urea solution, R2 = second period of recovery). 1. During control periods sheep on low protein diet have a greater capacity of urea retention than sheep on regular diet, under antidiuretic conditions (inulin U/P = 200). The following data (means +/- S.D.) are all reduced in animals on low protein diet: TEu by 36% (0.38 +/- 0.19 vs. 0.59 +/- 0.28 for normal protein sheep, p less than 0.05), Cu by 55% (0.50 +/- 0.19 vs. 1.15 +/- 0.49 ml.min-1.kg-1 for normal sheep, p less than 0.01) and amount of urea excreted by 80% (2.1 +/- 0.7 vs. 10.4 +/- 2.7 mg.min-1 for normal sheep, p less than 0.01). 2. The linear regression analysis of the relationship between tubular reabsorption of urea and its filtered amount shows that the capacity of urea retention is significantly higher in low protein sheep and that the difference between the two groups is greater as the filtered amount increases. Following 1M and 3M perfusions, the capacity of urea reabsorption by the perfused kidneys is significantly decreased in low protein animals whereas there is no change in the normal ones. The result is that perfused kidneys of the low protein sheep increase the amount of urea excreted during these periods: urine concentration of urea (Uu) increases by 55% during R1 and by 144% during R2, TEu increases by 60% during R1 and by 147% during R2 and Cu increases by 40% during R1 and by 95% during R2, without any variation of urine flow rate. These changes could be understood, provided that an important transfer of the perfused urea to the renal medulla in the low protein sheep would reduce the concentration gradients which enhance urea passive reabsorption from the collecting ducts.(ABSTRACT TRUNCATED AT 250 WORDS)