Concerted regulation of renal plasma flow and glomerular filtration rate by renal dopamine and NOS I in rats on high salt intake.

Under high sodium intake renal dopamine (DA) increases while NOS I expression in macula densa cells (MD) decreases. To explore whether renal DA and NOS I, linked to natriuresis and to the stability of the tubuloglomerular feedback, respectively, act in concert to regulate renal plasma flow (RPF) and glomerular filtration rate (GFR). Male Wistar rats were studied under a normal sodium intake (NS, NaCl 0.24%) or a high sodium intake (HS, NaCl 1% in drinking water) during the 5 days of the study. For the last two days, the specific D1-like receptor antagonist SCH 23390 (1 mg kg bwt-1 day-1, sc) or a vehicle was administered. HS intake increased natriuresis, diuresis, and urinary DA while it decreased cortical NOS I expression (P < 0.05 vs. NS), Nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) activity in MD (P < 0.001 vs. NS) and cortical nitrates+nitrites (NOx) production (NS 2.04 ± 0.22 vs. HS 1.28 ± 0.10 nmol mg protein-1, P < 0.01). Treatment with SCH 23390 to rats on HS sharply decreased hydroelectrolyte excretion (P < 0.001 vs. HS) while NOS I expression, NADPH-d activity and NOx production increased (P < 0.05 vs. HS for NOS I and P < 0.001 vs. HS for NADPH-d and NOx). SCH 23390 increased RPF and GFR in HS rats (P < 0.01 HS+SCH vs. HS). It did not cause variations in NS rats. Results indicate that when NS intake is shifted to a prolonged high sodium intake, renal DA through the D1R, and NOS I in MD cells act in concert to regulate RPF and GFR to stabilize the delivery of NaCl to the distal nephron.

Chronic Nicotine Exposure Abolishes Maternal Systemic and Renal Adaptations to Pregnancy in Rats.

Pregnancy is characterized by maternal systemic and intrarenal vasodilation, leading to increases in the renal plasma flow (RPF) and glomerular filtration rate (GFR). These responses are mainly mediated by nitric oxide (NO) and relaxin. The impact of cigarette smoking on the maternal adaptations to pregnancy is unclear. Here we evaluated the effects of chronic exposure to nicotine on systemic and intrarenal parameters in virgin (V) and 14-day pregnant (P) Wistar rats. V and P groups received saline or nicotine (6 mg·kg(-1)·day(-1)) respectively, via osmotic minipumps for 28 days, starting 14 days before pregnancy induction. Nicotine induced a 10% increase in blood pressure in the V group and minimized the characteristic pregnancy-induced hypotension. Renal sympathetic nerve activity (rSNA) and baroreflex sensitivity were impaired by nicotine mainly in the P group, indicating that the effect of nicotine on blood pressure was not mediated by nervous system stimulation. Nicotine had no effect on GFR in the V rats but reduced GFR of the P group by 30%. Renal expression of sodium and water transporters was downregulated by nicotine, resulting in increased fractional sodium excretion mainly in the P group, suggesting that nicotine compromised the sodium and water retention required for normal gestation. There was a reduction in the expression of inducible NO synthase (iNOS) in both the kidney tissue and renal artery, as well as in the expression of the relaxin receptor (LGR7). These results clearly show that nicotine induced deleterious effects in both virgin and pregnant animals, and abolished the maternal capacity to adapt to pregnancy.

Ovariectomy causes overexpression of renal Na(+),K(+)-ATPase and sodium-sensitive hypertension in adult Wistar rats.

We investigated the effect of ovariectomy(oVx) on renal and systemic hemodynamic, electrolyte excretion and total and dephosphorylated Na(+),K(+)-ATPase α1 subunit (t-d-NKA) in normotensive Wistar rats under a normal sodium (NS, 0.24%) or high sodium (HS, 1%) intake versus intact female (IF). On NS intake, t-d-NKA was higher in oVx rats and overexpressed in the thick ascending limbs (P < .01 vs. IF) and renal plasma flow was increased. On HS intake, oVx rats maintained a greater dephosphorylated NKA, excreted less sodium, and developed arterial hypertension (134 ± 4 vs. IF 112 ± 5 mm Hg, P < .05). Sodium load caused salt-sensitive hypertension in oVx Wistar rats.

Magnésio urinário, plasmático e eritrocitário: validação do método de análise por espectrofotometria de absorção atômica com chama / Magnesium contents in urine, plasma and erythrocyte samples: validation of analytical methodology using flame atomic absorption spectrophotometry

Neste estudo foi validada a metodologia de análise de magnésio urinário, plasmático e eritrocitário por espectrofotometria de absorção atômica com chama. As análises foram realizadas em pools de amostras de urina, de plasma e de eritrócitos de humanos. Para a validação, foram considerados os parâmetros de linearidade da curva-padrão, faixa de trabalho, limite de detecção (LD), limite de quantificação (LQ), precisão e exatidão da medição. Os LD e LQ da curva foram, respectivamente, de 0,006 e 0,021 μg/mLde Mg para urina e plasma, e de 0,003 e 0,010 μg/mL de Mg para eritrócitos. A faixa linear de trabalho para determinação de Mg foi entre 0,05 e 0,5 μg/mL de Mg, e as curvas-padrão apresentaram coeficientes de correlação maiores do que 0,99, que demonstram a linearidade da metodologia. As precisões intra e interensaio superiores a 90 por cento foram consideradas adequadas. As recuperações obtidas, usando-se materiais de referência certificados, foram de 101 por cento e de 97 por cento, respectivamente, em urina e plasma. As médias de recuperação por adição de padrão foram de 87 por cento para urina e eritrócitos e de 91 por cento para plasma. A metodologia avaliada foi linear, sensível, seletiva, precisa e exata; portanto, são confiáveis os resultados obtidos.

Treatment with pyrrolidine dithiocarbamate improves proteinuria, oxidative stress, and glomerular hypertension in overload proteinuria.

We evaluated whether the blockade of the proinflammatory transcription factor NF-kappaB would modify the oxidative stress, inflammation, and structural and hemodynamic alterations found in the kidney as a result of massive proteinuria. Twenty male Sprague-Dawley rats were injected with 2 g of BSA intraperitoneally daily for 2 wk. Ten of them received in addition the inhibitor of NF-kappaB activation pyrrolidine dithiocarbamate (PDTC; 200 mg.kg(-1).day(-1) sc) and the rest received vehicle. Seven rats that received intraperitoneal saline were used as controls. Glomerular hemodynamics were studied after 14 days. Markers of oxidative stress (NF-kappaB subunit p65+ cells, 3-nitrotyrosine, and 4-hydroxynonenal), inflammation (cortical CD68+ cells and NOS-II), and afferent arteriole damage were assessed by immunohistochemistry and morphometry. Activity of antioxidant enzymes superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase was evaluated in renal cortex and medulla. Albumin overload induced massive proteinuria, oxidative stress with reduced activity of antioxidant enzymes, NF-kappaB activation, inflammatory cell infiltration, a significant presence of proteinaceous casts, systemic and glomerular hypertension, as well as arteriolar remodeling. Treatment with PDTC prevented or improved all of these findings. In this model of nephrotic syndrome, we demonstrate a key role for oxidative stress and inflammation in causing systemic and glomerular hypertension and proteinuria. Oxidative stress and inflammation may have a key role in accelerating renal injury associated with intense proteinuria.

Renal function and cardiopulmonary bypass in pediatric cardiac surgical patients.

We studied prospectively the perioperative changes of renal function in nine children undergoing cardiac surgery with cardiopulmonary bypass (CPB). Glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) were measured with inulin and (131)I-hippuran clearances before CPB, during hypo and normothermic CPB, following sternal closure and 1 h postoperatively. Urinary alpha glutathione S-transferase (alpha GS-T) was measured pre- and postoperatively as a marker for tubular cellular damage. Plasma and urine creatinine and electrolytes were measured. Free water, osmolal and creatinine clearances, as well as fractional excretion of sodium (FeNa) and potassium transtubular gradient (TTKG) were calculated. GFR was normal before and after surgery. ERPF was low before and after surgery; it increased significantly immediately after CPB. Filtration fraction (FF) was abnormally elevated before and after surgery; however, a significant decrease during normothermic CPB and sternal closure was found. Alpha GS-T presented a moderate, but nonsignificant increase postoperatively. FeNa also increased in this period, but not significantly. Creatinine, osmolal, free water clearances, as well as TTKG, were normal in all patients pre- and postoperatively. We conclude that there is no evidence of clinically significant deterioration of renal function in children undergoing repair of cardiac lesions under CPB. Minor increases of alpha GS-T in urine postoperatively did not confirm cellular tubular damage. There was no tubular dysfunction at that time.

Vascular and renal effects of dopamine during extracellular volume expansion: Role of nitric oxide pathway.

OBJECTIVE: The aim of the study was to determine the possible role of NO-system activation in vascular and renal effects of the dopaminergic system and the probable interaction between both systems during acute volume expansion in rats. DESIGN AND METHODS: Expanded (10% bw) and non-expanded anaesthetized male Wistar rats were treated with haloperidol, a DA receptor antagonist (3 mg/kg bw, ip). Mean arterial pressure, diuresis, natriuresis, renal plasma flow, glomerular filtration rate, nitrites and nitrates excretion (NOx) were determined. NADPH diaphorase activity was measured using a histochemistry technique in kidney, aorta and renal arteries. NOS activity in kidney and aorta from expanded and non-expanded animals was determined with L-[U14C]-arginine substrate, in basal conditions and after DA (1 microM) administration. RESULTS: The hypotensive effect of L-arg and hypertension induced by L-NAME were not modified by haloperidol. This blocker reverted the increase in diuresis, natriuresis and RPF induced by L-arg in both groups. Dopaminergic blockade induced a decrease in NOx excretion and in NADPH-diaphorase activity in glomeruli, proximal tubule and medullar collecting duct and in endothelium and vascular smooth muscle of renal arteries. DA induced an increase in NOS activity in renal medulla and cortex in both groups, but no changes in the aorta were observed. CONCLUSIONS: Our results suggest that renal DA would be associated with the renal response induced by NO during extracellular volume expansion. NO-system activation would be one of the mechanisms involved in renal DA activity during saline load, but NO appears not to be involved in DA vascular effects.

Long-term effects of maternal diabetes on vascular reactivity and renal function in rat male offspring.

Fetal growth impairment can occur in pregnancy complicated by diabetes. Although several studies have focused the effects of nutritional status on intrauterine development, the long-term impact of maternal diabetes on vascular and renal function in the offspring is poorly investigated. In the present study, blood pressure profiles and renal function parameters were investigated in the offspring of diabetic rats (DO). Female rats were made diabetic throughout gestation with a single dose of streptozotocyn (STZ) 10 d before mating. After weaning, the offspring had free access to food and water. Arterial pressure was evaluated every 15 d. Functional and morphometric kidney studies were performed in newborn, 3, 6 and 12-mo-old male rats in DO and in controls, C. Although maternal diabetes did not affect nephron number in the young adult rat, glomerular hypertrophy developed from 3 mo on. Glomerular Filtration Rate and Renal Plasma Flow were observed to be significantly decreased in DO when compared with C, from 3 mo on. In DO, hypertension was observed from 8 wk on and persisted elevated throughout the experimental period (12 mo). Vascular reactivity, evaluated in mesenteric arterial bed showed a decreased endothelium-dependent vasodilatation in 12-mo-old DO animals, while preserved response to sodium nitroprusside was demonstrated. Our data show that exposure to intrauterine diabetes induced by STZ does not affect nephron number in the young offspring but can cause permanent changes in Nitric Oxide (NO)-related vascular response, which, in turn may accelerate the natural age-related nephron loss.

Effects of creatine supplementation on body composition and renal function in rats.

BACKGROUND: The aim of the present study was to evaluate the long-term effects of oral creatine supplementation on renal function and body composition (fat and lean mass) in an experimental model. METHODS: Male Wistar rats were supplemented with creatine (2 g.kg(-1) of food) for 10 wk in combination with treadmill exercise, 12 m.min(-1), 1 h.d(-1) (CREAT + EX, N = 12) or not (CREAT, N = 10), and compared with exercised animals without creatine supplementation (EX, N = 7) and CONTROL animals, N = 7. Body composition and bone mineral density (BMD) were determined by dual x-ray absorptiometry and glomerular filtration rate (GFR) and renal plasma flow (RPF) were measured by inulin and paraaminohippurate clearance, respectively. RESULTS: At the end of the study (post), CREAT+EX presented higher lean mass and lower fat mass than CREAT, EX or CONTROL (349.7 +/- 19.7 vs 313.3 +/- 20.3, 311.9 +/- 30.8, 312.4 +/- 21.0 g and 5.7 +/- 2.3 vs 10.0 +/- 3.3, 9.8 +/- 1.5, 10.0 +/- 3.5%, P < 0.05, respectively). Post lean/fat mass ratio was higher than baseline only in CREAT + EX (18.9 +/- 7.2 vs 8.6 +/- 1.8, P < 0.05). Post BMD was significantly higher than baseline in all groups. GFR and RPF were lower in CREAT versus CONTROL (0.5 +/- 0.1 vs 1.0 +/- 0.1 and 1.5 +/- 0.2 vs 2.4 +/- 0.5 mL.min(-1), P < 0.05, respectively). CONCLUSION: Creatine supplement in combination with exercise increased the proportion of lean mass more than EX or CREAT alone. The use of creatine alone induced an important and significant reduction of both RPF and GFR.

Effect of unilateral nephrectomy on renal function of diabetic rats.

Glomerular alterations of experimental diabetes mellitus are observed in animals submitted to a reduction in renal mass, suggesting that some mechanisms responsible for the progression of renal disease are common. The aim of this study was to investigate the effect of nephrectomy on the renal function and morphology of diabetic rats. Male Wistar rats were divided into 4 groups: control (C), n=8; diabetic (DM), n=8; non-diabetic nephrectomized (Nx), n=8; (DMNx), n=9. DM was induced by streptozotocin (65 mg/Kg), and animals were treated with insulin. After 12 weeks, the glomerular filtration rate (GFR), renal plasma flow (RPF) and mean arterial pressure (MAP) were evaluated in unanaesthetized animals. Glomerular volume (GV), glomerular sclerosis index (GSI), mesangial volume density (Vvmes) and glomerular capillary surface density (Svcap) were also evaluated. Results show that kidney weight increased in Nx groups, being higher in DMNx. GFR was higher in Nx groups as was RPF, being higher in DMNx. RVR was lower in Nx groups, especially in DMNx. MAP was not different among the groups. RPF and GFR showed a high correlation for the DMNx group (r=0.95, p=0.02). The DMNx group showed a correlation between RVR and GFR (r=-0.96, p=0.005). The GV increased in Nx groups, and the GSI was higher in DMNx. Vvmes and Svcap increased in DMNx group. In summary, Nx groups developed similar degrees of glomerular hypertrophy, but only DMNx showed an increased value for GSI. The present data suggest that the acceleration of glomerular lesions in DMNx animals was more closely associated to hemodynamic adaptations than to glomerular hypertrophy.

Effect of strenuous maternal exercise before and during pregnancy on rat progeny renal function.

The effects of strenuous exercise before and during pregnancy on the renal function and morphological alterations of the progeny were determined in a study on female Wistar rats. This research was done based on a previous study carried out in our laboratory, which showed morphological alterations in rats submitted to this kind of exercise. As the form is related to the function, the physiological relevance of submitting a pregnant female to a high-intensity exercise training regimen could be explained by the fact that morphological alterations can influence kidney function. The animals were assigned to one of two groups: control animals that did not exercise during pregnancy and trained animals that swam for 120 min 5 days a week for 8 weeks before pregnancy and daily for 60 min over a period of 8 weeks starting on the second day of pregnancy. Seven rats of each group were analyzed for morphological alterations and for renal function. The progeny of the rats used for morphological evaluation were born by cesarean section and the progeny of the animals used to evaluate renal function were born normally. The progeny were two months old when renal function was evaluated. Fertility and morbidity were the same for both groups. Strenuous maternal exercise had no significant influence on glomerular filtration rate (GFR) but renal plasma flow was lower in the progeny of the trained group (mean +/- SD, 16.65 +/- 3.77 ml min(-1) kg(-1)) compared to the progeny of the control group (33.42 +/- 2.56 ml min(-1) kg(-1)). Antidiuretic and antinatriuretic effects on the progeny of the trained group were observed, since urine flow as percentage of GFR and the fraction of urinary sodium excretion were lower in this group (1.38 +/- 0.10 and 0.60 +/- 0.04%, respectively) compared to the progeny of the control group (2.36 +/- 0.11 and 1.55 +/- 0.20%, respectively). Moreover, in this exercise program, fetuses from trained animals were small-sized (2.45 +/- 0.19 vs 4.66 +/- 2.45 g for control animals) and showed lower differentiation compared to fetuses from the control group. These effects were probably caused by caloric restriction, hypoxia and reduction of umbilical cord length.

Effect of strenuous maternal exercise before and during pregnancy on rat progeny renal function

The effects of strenuous exercise before and during pregnancy on the renal function and morphological alterations of the progeny were determined in a study on female Wistar rats. This research was done based on a previous study carried out in our laboratory, which showed morphological alterations in rats submitted to this kind of exercise. As the form is related to the function, the physiological relevance of submitting a pregnant female to a high-intensity exercise training regimen could be explained by the fact that morphological alterations can influence kidney function. The animals were assigned to one of two groups: control animals that did not exercise during pregnancy and trained animals that swam for 120 min 5 days a week for 8 weeks before pregnancy and daily for 60 min over a period of 8 weeks starting on the second day of pregnancy. Seven rats of each group were analyzed for morphological alterations and for renal function. The progeny of the rats used for morphological evaluation were born by cesarean section and the progeny of the animals used to evaluate renal function were born normally. The progeny were two months old when renal function was evaluated. Fertility and morbidity were the same for both groups. Strenuous maternal exercise had no significant influence on glomerular filtration rate (GFR) but renal plasma flow was lower in the progeny of the trained group (mean ñ SD, 16.65 ñ 3.77 ml min-1 kg-1) compared to the progeny of the control group (33.42 ñ 2.56 ml min-1 kg-1). Antidiuretic and antinatriuretic effects on the progeny of the trained group were observed, since urine flow as percentage of GFR and the fraction of urinary sodium excretion were lower in this group (1.38 ñ 0.10 and 0.60 ñ 0.04 percent, respectively) compared to the progeny of the control group (2.36 ñ 0.11 and 1.55 ñ 0.20 percent, respectively). Moreover, in this exercise program, fetuses from trained animals were small-sized (2.45 ñ 0.19 vs 4.66 ñ 2.45 g for control animals) and showed lower differentiation compared to fetuses from the control group. These effects were probably caused by caloric restriction, hypoxia and reduction of umbilical cord length.

Compensation increase in organic anion excretion in rats with acute biliary obstruction: role of the renal organic anion transporter 1.

The purpose of the present study was to examine in rats the effects of acute bile duct ligation on the expression of the organic anion transporter 1 in the kidney and the consequences of these effects on the systemic clearance of organic anions, particularly on P-aminohippurate (PAH) clearance, since it has been viewed as the prototypic organic anion. Male Wistar rats underwent bile duct ligation (BDL rats). Pair-fed sham-operated rats served as controls. All studies were carried out 21 h after surgery. Our data revealed that BDL rats had a higher expression of organic transporter 1 protein in kidney cortex homogenates. Accordingly, systemic clearance of PAH and urinary excretion of PAH were both higher in BDL rats. These findings suggest that impairment of the liver function after BDL is followed by a distinct and statistically significant increase in renal excretion of PAH, indicating a possible compensation mechanism.

Reposiçäo volêmica no choque hemorrágico: a soluçäo empregada faz diferença em relaçäo aos efeitos hemodinâmicos e renais? / Hemorrhagic shock volume replacement: does the solution make a difference in hemodynamic and renal effects?

Justificativa e objetivos - O emprego de pequenos volumes de soluçäo hipertônica (SH) isoladamente ou em associaçäo à soluçäo de dextran 70 a 6 por cento (SHD), abre novas perpectivas no manuseio da reposiçäo volêmica durante o choque hipovolêmico, em relaçäo ao emprego de soluçöes cristalóides. A pesquisa experimental tem como objetivo verificar se o tipo de soluçäo empregada na reposiçäo do choque hemorrágico apresenta alguma diferença em relaçäo aos efeitos hemodinâmicos e renais. Método - Foram utilizados 24 cäes anestesiadoscom pentobarbital sódico. Após retirada de 40 por cento do volume sanguíneo, os cäes foram distribuídos de forma aleatória em grupos de 8 animais, de acordo com a soluçäo empregada para a reposiçäo volêmica: G1 - SH a 7,5 por cento em volume de 4ml.kg-1; G2 - soluçäo de Ringer com lactato (RL) na proporçäo 2:1 em relaçäo ao volume de sangue retirado; e G3 - SHD em volume de 4ml.kg-1. Foram estudados os seguintes atributos: frequência cardíaca (FC), pressäo arterial média (PAM), pressäo venosa central (PVC), fluxo sanguíneo aortico (FAo), resistência vascular aórtica (RvAo), fluxo plasmático renal (FPR), ritmo de filtraçäo glomerular (RFG), fluxo sanguíneo renal, débito urinário (DU), resistência vascular renal, excreçäo urinária de sódio (EFNa), depuraçäo osmolar (Dosm) e depuraçäo de água livre (DH2O). Os atributos PAM, PVC, FAo foram estudados nos momentos: M1 (controle); M2 - após a retirada dos 40 por cento da volemia; M3, M4 e M5 - imediatamente e após 15 e 60 min da reposiçäo volêmica, respectivamente. Os demais atributos estudados nos momentos: M1 (controle); M2 e M3-15 e 60 min da reposiçäo volêmica, respectivamente. Resultados - A reposiçäo com RL (G2) aumentou o FAo e a PVC em M3 e M4, em níveis superiores aos determinados pela reposiçäo com pequenos volumes (G1 e G3). Näo houve diferença significante da PAM entre os grupos, que se elevou após a reposiçäo, mas näo retornou aos níveis do controle. O DU aumentou significativamente em G2 (RL), com aumento da DH2O nesse grupo em G3 (SHD). Conclusöes - A reposiçäo com RL determina excessiva expansäo volêmica, enquanto a reposiçäo com SH e SDH determina boa expansäo volêmica, sem diferença significante entre elas. Todas as soluçöes mantêm a hemodinâmica e funçäo renais, com o RL provocando aumento do débito urinário

Effects of dietary lipids on renal function of aged rats.

Normal aging is accompanied by renal functional and morphological deterioration and dietetic manipulation has been used to delay this age-related decline. We examined the effects of chronic administration of diets containing 5% lipid-enriched diet (LD, w/w) on renal function of rats at different ages. Three types of LD were tested: canola oil, fish oil and butter. Mean systemic tail-cuff blood pressure and glycemia remained within the normal range whatever the age and the diet of the animals. Proteinuria began to rise from the 8th month in the groups ingesting LD, while in the control group it increased significantly (above 10 mg/24 h) only after the 10th month. With age, a significant and progressive decline in glomerular filtration rate (GFR) and renal plasma flow was observed in the LD groups but after 6 months of lipid supplementation, the decline in these parameters was more marked in the butter and fish oil groups. By the 18th month, the lowest GFR level was observed in the group ingesting the butter diet (2.93 +/- 0.22 vs 5.01 +/- 0.21 ml min(-1) kg(-1) in control, P<0.05). Net acid excretion, evaluated in 9- and 18-month-old rats, was stimulated in the fish oil group when compared both to control and to the other two LD groups. These results suggest that even low levels of LD in a chronic nutritional regimen can modify the age-related changes in renal function and that the impact of different types of lipid-supplemented diets on renal function depends on the kind of lipid present in the diet.

Effects of dietary lipids on renal function of aged rats

Normal aging is accompanied by renal functional and morphological deterioration and dietetic manipulation has been used to delay this age-related decline. We examined the effects of chronic administration of diets containing 5 percent lipid-enriched diet (LD, w/w) on renal function of rats at different ages. Three types of LD were tested: canola oil, fish oil and butter. Mean systemic tail-cuff blood pressure and glycemia remained within the normal range whatever the age and the diet of the animals. Proteinuria began to rise from the 8th month in the groups ingesting LD, while in the control group it increased significantly (above 10 mg/24 h) only after the 10th month. With age, a significant and progressive decline in glomerular filtration rate (GFR) and renal plasma flow was observed in the LD groups but after 6 months of lipid supplementation, the decline in these parameters was more marked in the butter and fish oil groups. By the 18th month, the lowest GFR level was observed in the group ingesting the butter diet (2.93 + or - 0.22 vs 5.01 + or - 0.21 ml min-1 kg-1 in control, P<0.05). Net acid excretion, evaluated in 9- and 18-month-old rats, was stimulated in the fish oil group when compared both to control and to the other two LD groups. These results suggest that even low levels of LD in a chronic nutritional regimen can modify the age-related changes in renal function and that the impact of different types of lipid-supplemented diets on renal function depends on the kind of lipid present in the diet

Renografía radioisotópica con diurético en la evaluación de los procesos obstructivos del tracto urinario superior en pacientes pediátricos / Diuresis renography in the evaluation of pediatric patients with dilated upper urinary tract

La renografía con diurético es una evaluación no invasiva aceptada para distinguir entre procesos obstructivos y procesos no obstructivos causantes de la dilatación del tracto urinario superior en pacientes pediátricos. La detección de las alteraciones obstructivas como resposables de la dilatación de los sistemas colectores renales es muy importante ya que éstas son causas previsibles de la insuficiencia renal. La utilización conjunta de estudios morfológicos como el ultrasonido, y de evaluaciones funcionales como la gammagrafía, proporcionan información anatomofuncional que nos permite conocer el verdadero estado morfológico y funcional de los riñones de forma objetiva. El 99mTc-MAG 3 es actualmente el radionúclido preferido para la renografía con diurético. En infantes como obstrucción de la unión pieloureteral, el renograma con diurético se manifiesta de formas distintas. Desde el punto de vista clínico, los casos se clasifican en aquellos con evidencia precisa de obstrucción grave y no hay daño renal. Las intervenciones quirúrgicas quedan indicadas en pacientes con obstrucción completa. La gran mayoría de los renogramas con diurético pueden ser correctamente interpretados con el simple análisis visual de las curvas de tiempo/actividad generadas por computadora, sin la ayuda de otros cálculos más complejos

A definite role for the kallikrein-kinin system in the renal hemodynamic response to an oral protein load during the aging process.

The effect of aging on the physiologic responses of renal plasma flow (RPF) and glomerular filtration rate to an acute oral protein load (renal reserve) is a poorly understood process. In this study of 37 healthy human volunteers, distributed among three groups (group 1: n = 13, age range 20-39 years; group 2: n = 13, age range 40-59 years; group 3: n = 11, age range 60-68 years), we evaluated the influence of age on some of the vasoactive systems such as plasma renin activity, urinary kallikrein, plasmatic prokallikrein, plasmatic kallikrein, and plasmatic kininogen on RPF and creatinine clearance (Ccr) in response to an acute oral protein load (1 g/kg body weight). The aging process diminished but did not cease the increments in RPF (group 1: 539.6 vs. 658.9 ml/min/1.73 m(2), p < 0. 001; group 2: 509.0 vs. 570.7 ml/min/ 1.73 m(2), p < 0.001; group 3: 453.9 vs. 506.0 ml/min/ 1.73 m(2), p < 0.001) and Ccr (group 1: 139. 7 vs. 166.5 ml/ min/1.73 m(2), p < 0.001; group 2: 126.6 vs. 142.2 ml/min/1.73 m(2), p < 0.001; group 3: 112.6 vs. 121.4 ml/min/ 1.73 m(2), p < 0.01) after a protein overload. The plasma renin activity did not change after a meat meal. On the other hand, all parameters regarding the kinin system changed significantly in the direction of increased bradykinin formation, despite aging (urinary kallikrein - group 1: 0.25 vs. 0.44 mU/ml, p < 0.005; group 2: 0.25 vs. 0.41 mU/ml, p < 0.005; group 3: 0.33 vs. 0.47 mU/ml, p < 0.005/plasmatic kininogen - group 1: 1.3 vs. 0.9 microg LBK/ml, p < 0.005; group 2: 1.1 vs. 0.7 microg LBK/ml, p < 0.005; group 3: 0.8 vs. 0.7 microg LBK/ml, p < 0.005). These findings indicate that: (1) the aging process narrows but does not cease the increment range in Ccr and RPF after acute oral protein ingestion; (2) increased bradykinin formation plays a definite role in the acute renal vasodilatory response, and (3) contrary to previous clinical studies, our results suggest that the renal reserve is progressively and significantly reduced during the aging process.