RESUMO
Previous studies have shown that pharmacological stimulation of a region denominated caudal pressor area (CPA), located in the caudal end of the ventrolateral medulla, induces increases in arterial blood pressure (BP). The aim of this study was to compare the responses on renal sympathetic nerve activity (rSNA) and BP responses mediated by stimulation of CPA or rostral ventrolateral medulla (RVLM), in intact or sino-aortic barodenervated rats. Male Wistar rats (300-350 g, n=15) were anesthetized (urethane 1.2 to 1.4 g/kg, i.v.) and artificially ventilated. The mean arterial pressure (MAP) and rSNA were measured during bilateral glutamate microinjection (10 nmo/100 nl) into the CPA or into the RVLM. Glutamatergic stimulation of the RVLM increased MAP (46+/-7 mm Hg) and rSNA (82+/-21%); during CPA stimulation, MAP and rSNA increased 60+/-7 mm Hg and 93+/-9%, respectively. However, despite the similarity of responses mediated by both regions, the duration of rSNA and blood pressure responses mediated by the CPA were significantly longer than the duration of the responses mediated by the RVLM. After barodenervation, there was an increase in the time-course and magnitude of sympathetic response only in response to RVLM stimulation but not in response to CPA. The results suggest a differential baroreceptor modulation on rSNA mediated by the ventrolateral medulla neurons. Glutamatergic activation of CPA neurons can cause large increases in the rSNA and BP with a weaker baroreceptor modulation when compared to responses mediated by the RVLM neurons.
Assuntos
Barorreflexo/fisiologia , Bulbo/citologia , Neurônios/fisiologia , Pressorreceptores/fisiologia , Análise de Variância , Animais , Barorreflexo/efeitos dos fármacos , Pressão Sanguínea/efeitos dos fármacos , Pressão Sanguínea/fisiologia , Ácido Glutâmico/farmacologia , Rim/inervação , Masculino , Bulbo/fisiologia , Microinjeções , Inibição Neural/efeitos dos fármacos , Inibição Neural/fisiologia , Neurônios/efeitos dos fármacos , Pressorreceptores/efeitos dos fármacos , Pressorreceptores/efeitos da radiação , Ratos , Ratos Wistar , Sistema Nervoso Simpático/fisiologia , Fatores de TempoRESUMO
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.
Assuntos
Composição Corporal/efeitos dos fármacos , Creatina/farmacologia , Suplementos Nutricionais , Dopagem Esportivo/métodos , Rim/efeitos dos fármacos , Condicionamento Físico Animal , Animais , Peso Corporal/efeitos dos fármacos , Densidade Óssea/efeitos dos fármacos , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Taxa de Filtração Glomerular/efeitos dos fármacos , Rim/patologia , Masculino , Músculo Esquelético/efeitos dos fármacos , Músculo Esquelético/patologia , Tamanho do Órgão , Ratos , Ratos Wistar , Valores de Referência , Fluxo Plasmático Renal/efeitos dos fármacosRESUMO
Several studies support the hypothesis that chronic diseases in adulthood might be triggered by events that occur during fetal development. This study examined the consequences of perinatal salt intake on blood pressure (BP) and carbohydrate and lipid metabolism in adult offspring of dams on high-salt [HSD; 8% (HSD2) or 4% (HSD1)], normal-salt (NSD; 1.3%), or low-salt (LSD; 0.15% NaCl) diet during pregnancy and lactation. At 12 wk of age, female Wistar rats were matched with adult male rats that were fed NSD. Weekly tail-cuff BP measurements were performed before, during, and after pregnancy. After weaning, the offspring received only NSD and were housed in metabolic cages for 24-h urine collection for sodium and potassium and nitrate and nitrite excretion measurements. At 12 wk of age, intra-arterial mean BP was measured, a euglycemic-hyperinsulinemic clamp was performed, and plasma lipids and nitrate and nitrite concentrations were determined. Tail-cuff BP was higher during pregnancy in HSD2 and HSD1 than in NSD and LSD dams. Mean BP (mm Hg) was also higher in the offspring of HSD2 (110 +/- 5) and HSD1 (107 +/- 5) compared with NSD (100 +/- 2) and LSD (92 +/- 2). Lower glucose uptake and higher plasma cholesterol and triacylglycerols were observed in male offspring from LSD dams (glucose uptake: HSD2 17 +/- 4, HSD1 15 +/- 3, NSD 11 +/- 3, LSD 4 +/- 1 mg . kg(-1) . min(-1); cholesterol: HSD2 62 +/- 6, HSD1 82 +/- 11, NSD 68 +/- 10, LSD 98 +/- 17 mg/dL; triacylglycerols: HSD2 47 +/- 15, HSD1 49 +/- 12, NSD 56 +/- 19, LSD 83 +/- 11 mg/dL). In conclusion, maternal salt intake during pregnancy and lactation has long-term influences on arterial pressure, insulin sensitivity, and plasma lipids of the adult offspring.