Postprandial glycemia in healthy subjects: Which probiotic dairy food is more adequate?

The consumption of probiotic-enriched dairy products has been associated with many health benefits, including anti-hyperglycemic activity. The effect on health is dependent on the type of probiotic culture used and the dairy product consumed. This study evaluated the effect of different probiotic-enriched dairy matrices (Minas Frescal cheese, Prato cheese, and whey dairy beverage) containing Lactobacillus casei on in vitro and in vivo anti-hyperglycemic activity. For this purpose, in vitro anti-hyperglycemic activity was determined by the inhibition of α-glucosidase and α-amylase activities, and a human study was performed with healthy individuals (n = 15, consumption of bread as a control; bread + Minas Frescal cheese; bread + Prato cheese; bread + dairy beverage) to assess the effects of different probiotic foods on postprandial glycemia. In vitro data showed that Prato cheese presented the highest lipid (36.9 g/100 g) and protein (26.5 g/100 g) contents as well as the highest α-amylase (60.7%) and α-glucosidase (52.6%) inhibition. The consumption of Prato cheese resulted in a lesser increase in blood glucose level (13 mg/dL) compared with the consumption of bread alone (19 mg/dL), Minas Frescal cheese (20 mg/dL), and whey dairy beverage (30 mg/dL), with glycemic indices similar to that observed for the control. The present results demonstrated a good correlation between in vitro and in vivo data, in which the type of dairy matrix affects the anti-hyperglycemic activity. It is concluded that the consumption of probiotic Prato cheese can contribute to the reduction of postprandial glycemia in healthy individuals.

Longitudinal association of adiposity and high-sensitivity C-reactive protein from adolescence into early adulthood.

BACKGROUND AND AIMS: Longitudinal studies relating adiposity with low-grade inflammation are scarce. We aimed to examine the longitudinal association between the cumulative exposure to adiposity and low-grade inflammation from adolescence into early adulthood. METHODS AND RESULTS: Data from a population-based cohort (EPITeen) (n = 1147) was analyzed. Body mass index (BMI), body fat percentage (BF%), waist circumference (WC), and waist-to-height ratio (WHtR) and high-sensitivity C-reactive protein (hsCRP) were ascertained at 13, 17 and 21 years of age and standardized for each wave. Generalized least squares models with a compound symmetry correlation structure were fitted to estimate the longitudinal effect of adiposity on hsCRP and results were presented as linear regression coefficients and 95% confidence intervals [ß (95%CI)].The final model estimated the association between the difference in adiposity between two consecutive evaluations (13-17 and 17 to 21-years-old), adjusted for previous adiposity and hsCRP levels, sex, parental education, leisure-time physical activity and fruits and vegetables intake. A positive association between the cumulative exposure to adiposity and final hsCRP was observed, in which the difference between adiposity indicators of two consecutive study waves was independently associated with hsCRP: 0.382 (0.299; 0.465) for BMI, 0.234 (0.164; 0.304) for WC, 0.395 (0.314; 0.477) for BF% and 0.195 (0.133; 0.258) for WHtR. CONCLUSION: A significant longitudinal effect of the accumulation of adiposity on low-grade inflammation was observed. The change in adiposity from consecutive study waves was shown to have a stronger effect on final hsCRP concentrations than both previous adiposity and hsCRP levels.

Novel milk-juice beverage with fermented sheep milk and strawberry (Fragaria × ananassa): Nutritional and functional characterization.

This study was aimed at developing a new functional fermented beverage manufactured with semi-skimmed sheep milk and strawberry pulp (Fragaria × ananassa Duch.) and commercial prebiotic ingredients. We also compared the performance of the yogurt starter cultures and a Lactobacillus plantarum strain (CECT_8328) with potential probiotic properties. We assessed the nutritional profile, bioactivity compounds, viability of lactic acid bacteria during storage, and survival of L. plantarum after in vitro simulated digestion during the storage period. The lactic acid bacteria were viable throughout the storage period, but only L. plantarum maintained good viability after simulated digestion. Nevertheless, neither inulin nor potato starch increased bacterial viability. The fermented semi-skimmed sheep milk strawberry beverages we developed are good sources of minerals and proteins.

Fermented whey dairy beverage offers protection against Salmonella enterica ssp. enterica serovar Typhimurium infection in mice.

Fermented whey dairy beverages are dairy products obtained by fermentation from a mixture of milk and whey. These beverages have important health benefits, which could be improved with the addition of probiotic cultures. This study assessed the protective effect of the cosupplementation of a probiotic culture (Lactobacillus casei 01) with a fermented whey dairy beverage against infection by Salmonella enterica ssp. enterica serovar Typhimurium in a murine model. Two fermented whey dairy beverages were prepared: conventional (FWB; starter culture) and probiotic (PFWB; starter and probiotic cultures). In the first set of experiments, Balb/C female mice were treated with FWB or PFWB, challenged with Salmonella Typhimurium, and analyzed for clinical signs, weight loss, and mortality for 20 d postinfection. In the second set of experiments, mice were treated with FWB or PFWB, challenged with Salmonella Typhimurium, and killed on d 10 postinfection. The liver, colon, and ileum were used for myeloperoxidase, eosinophil peroxidase, and histological analysis and translocation to the liver. The contents from the small intestine were used for secretory IgA determination. The FWB treatment showed a better effect on animal survival (70%), translocation of the pathogen to the liver (2 out of 10), histopathology (fewer lesions), and inflammation than PFWB, which presented 50% animal survival, translocation in 5 out of 10 animals, and higher lesions. The control group presented 40% animal survival, translocation in 6 out of 10 animals, and severe lesions. Therefore, FWB was deemed to have a greater protective effect against Salmonella Typhimurium infection in the murine model compared with PFWB.

Developmental trajectories of adiposity from birth until early adulthood and association with cardiometabolic risk factors.

OBJECTIVE: To identify developmental trajectories of adiposity from birth until early adulthood, and to investigate how they relate with cardiometabolic risk factors at 21 years of age. METHODS: Participants' weight and height measurements were obtained using the EPITeen cohort protocol at 13, 17 and 21 years of age, and extracted from child health books as recorded during health routine evaluations since birth. Blood pressure, triglycerides, cholesterol and insulin resistance (HOMA-IR) were assessed at 21 years. Trajectories were defined using 719 participants contributing 11 459 measurements. The individual growth curves were modelled using mixed-effects fractional polynomial, and the trajectories were estimated using normal mixture modelling for model-based clustering. Differences in cardiometabolic risk factors at 21 years according to adiposity trajectories were estimated through analysis of covariance (ANCOVA), and adjusted means are presented. RESULTS: Two trajectories-'Average body mass index (BMI) growth' (80.7%) and 'Higher BMI growth' (19.3%)-were identified. Compared with those in 'Average BMI growth', 'Higher BMI growth' participants were more frequently delivered by caesarean section, mothers were younger and had higher BMI, and parental education was lower; and at 21 years showed higher adjusted mean systolic (111.6 vs 108.3 mm Hg, P<0.001) and diastolic blood pressure (71.9 vs 68.4 mm Hg, P<0.001), and lower high-density lipoprotein cholesterol (53.3 vs 57.0 mg dl(-1), P=0.001). As there was a significant interaction between trajectories and sex, triglycerides and HOMA-IR were stratified by sex and we found significantly higher triglycerides, in males, and higher HOMA-IR in both sexes in 'Higher BMI growth' trajectory. All the differences were attenuated after adjustment for BMI at 21 years. CONCLUSIONS: In this long-term follow-up, we were able to identify two adiposity trajectories, statistically related to the BMI and cardiometabolic profile in adulthood. Our results also suggest that the impact of the adiposity trajectory on cardiometabolic profile is mediated by current BMI.

The lymphocyte-to-monocyte ratio: an added value for death prediction in heart failure.

BACKGROUND AND AIM: Leukocytes and their subpopulation have been long implicated in the progression of the syndrome of heart failure (HF), especially heart infiltration cells. Previous reports have suggested that they can predict worse outcome in patients with HF, and can also affect the function of other cells and myocardial extracellular matrix remodeling process. However, the lymphocyte-to-monocyte ratio (LMR) and its possible value as prognostic marker have not been evaluated. METHODS AND RESULTS: A total of 390 patients with acute HF were recruited and followed for 6 months. Their total blood count with leukocyte differential was obtained. Two groups were formed according to the endpoints of HF death and optimal cut-off value of LMR, and were compared. A multivariate Cox-regression model was used to establish the prognostic value with the endpoints of HF and all-cause mortality. Median age of the patients was 78 years and 48.5% of them were men. No major difference was observed between the clinical characteristics of the two groups. Patients who died of HF had significantly higher values of B-type natriuretic peptide and lower values of LMR. Leukocyte and monocyte counts revealed a multivariate-adjusted risk for both endpoints, whereas relative lymphocyte counts had only significant value for all-cause mortality. The multivariate-adjusted hazard ratios for the 6-month HF and all-cause mortality in patients with LMR values < 2.0 were, respectively, 2.28 (95% CI: 1.25-4.15) and 2.39 (95% CI: 1.39-4.10). CONCLUSION: Our results show that, upon discharge from hospital after an episode of acute HF, a lower value of LMR is independently associated with a higher risk of mortality within 6 months.

Increased circulating platelet microparticles as a potential biomarker in asthma.

BACKGROUND: Endothelial (EMPs) and platelet microparticles (PMPs) have been studied as biomarkers in several inflammatory diseases and as central players in intercellular communication. METHODS: In this cross-sectional study, we aimed to assess microparticle levels in asthma. Circulating microparticles and inflammatory and angiogenic markers were assessed by clinical and laboratorial evaluation, flow cytometry, and immunoassays, in a group of 20 asthmatic and 15 nonasthmatic subjects. RESULTS: Circulating levels of PMPs (either CD31+/42b+ or CD31+/42b+/AnV+) were significantly increased in asthmatics (P = 0.021) even after adjustment for confounders. Apoptotic EMPs (CD31+/42b--/AnV+) were significantly increased before (P = 0.005) but not after adjustments (P = 0.117). CONCLUSIONS: We propose that PMPs may be putative asthma biomarkers, playing a role in asthma pathophysiology.

Substance P antagonist improves both obesity and asthma in a mouse model.

BACKGROUND: Evidence suggests a causal relationship between obesity and asthma; however, the underlying mechanisms remain unknown. Substance P (SP), involved in neurogenic inflammation by acting through its receptor NK1-R, seems to participate in obese-asthma phenotype in mice. OBJECTIVES: To evaluate the effect of a selective substance P receptor antagonist on a mouse model of diet-induced obesity and asthma. METHODS: Diet-induced obese Balb/c mice were sensitized and challenged with ovalbumin (OVA) and treated with a selective NK1-R antagonist or placebo. Serum glucose, insulin, IL-6, resistin, and OVA-specific IgE levels were quantified. A score for peribronchial inflammation in lung histology was used. Cells were counted in bronchoalveolar lavage fluid. Adipocyte sizes were measured. RESULTS: Ovalbumin-obese mice treated with NK1-R antagonist had lower weight (P = 0.0002), reduced daily food intake (P = 0.0021), reduced daily energy intake (P = 0.0021), reduced surface adipocyte areas (P < 0.0001), lower serum glucose (P = 0.04), lower serum insulin (P = 0.03), lower serum IL-(P = 0.0022), lower serum resistin (P = 0.0043), lower serum OVA-specific IgE (P = 0.035), and lower peribronchial inflammation score (P < 0.0001) than nontreated OVA-obese mice. We observed an interaction between obesity, allergen sensitization, and treatment with NK1-R antagonist for metabolic and systemic biomarkers, and for allergen sensitization and bronchial inflammation, showing a synergy between these variables. CONCLUSION & CLINICAL RELEVANCE: In an experimental model of obesity and asthma in mice, NK1-R blockade improved metabolic and systemic biomarkers, as well as allergen sensitization and bronchial inflammation. These positive effects support a common pathway in the obese-asthma phenotype and highlight SP as a target with potential clinical interest in the obese-asthma epidemics.

Predictors and outcomes of disseminated tuberculosis in an intermediate burden setting.

SETTING: University-affiliated hospital located in Porto, North Portugal, an area with a low to intermediate incidence of tuberculosis (TB). OBJECTIVE: To identify predictors and outcomes of disseminated TB (dTB). DESIGN: A cohort of patients diagnosed with TB between 2007 and 2013 was retrospectively analysed. Patients with dTB criteria were characterized and compared to single organ TB cases. Factors independently associated with dTB were determined by multivariate logistic regression analysis. RESULTS: A total of 744 patients were analysed, including 145 with dTB. Independent risk factors for dTB were pharmacological immunosuppression (OR 5.6, 95% CI 2.8-11.3), HIV infection (OR 5.1, 95% CI 3.1-8.3), chronic liver failure or cirrhosis (OR 2.3, 95% CI 1.4-4.1) and duration of symptoms (OR 2.3, 95% CI 1.4-3.8). Compared to single organ TB, the clinical presentation of dTB patients differed by the absence of haemoptysis (OR 3.2, 95% CI 1.3-8.4) and of dyspnoea (OR 1.9, 95% CI 1.2-3.1), presence of weight loss (OR 1.8, 95% CI 1.1-2.9), night sweats (OR 1.7, 95% CI 1.1-2.7) and bilateral lung involvement (OR 4.4, 95% CI 2.8-7.1). Mortality and time until culture conversion were higher for dTB patients, although not reaching statistical significance. CONCLUSION: Immunosuppressive conditions and chronic liver failure or cirrhosis were associated with increased risk of dTB. The haematogenous spread may be dependent on longer symptomatic disease and usually progresses with bilateral lung involvement.

Energy restriction, exercise and atorvastatin treatment improve endothelial dysfunction and inhibit miRNA-155 in the erectile tissue of the aged rat.

BACKGROUND: Endothelial dysfunction underlies cardiovascular disease that frequently affects aged individuals. Characterized by local decrease in nitric oxide, it results from down-regulation of endothelial nitric oxide synthase (eNOS) expression/activity. Aiming to elucidate the molecular mechanisms involved in age-related endothelial dysfunction and to unveil potential therapeutic targets, we tested how diet pattern, exercise and atorvastatin modulate the expression of eNOS, inducible NOS (iNOS), endothelin-1, sirtuins (SIRT) and microRNA-155 in the erectile tissue of high-fat fed aged rats. METHODS: Sprague-Dawley male rats fed with high-fat diet until they completed 12 months were grouped and subjected to energy restriction (ER), ER and atorvastatin, or, ER, atorvastatin and physical exercise. Controls were fed with standard rodent chow. The blood pressure was measured using the tail-cuff method before sacrifice at 18 months. Glucose, total cholesterol, HDL, triglyceride and CRP were assessed in blood and eNOS, endothelin-1, iNOS and sirtuins were detected by immunofluorescence in the penis sections; eNOS, endothelin-1, iNOS, SIRT2-4 and SIRT6-7 were semi-quantified by western blotting in tissue homogenates. MicroRNA-155 was quantified using RT-PCR in formalin-fixed paraffin embedded sections. To compare the studied variables, two-tail student t test was used. RESULTS: Atorvastatin promotes eNOS expression and is more efficient than ER or exercise in the control of hyperlipidemia and inflammation. Among the studied sirtuins, detected for the first time in the erectile tissue of the aged rat, SIRT2 aligns with eNOS expression. Both proteins exhibit over-expression in animals with combined exercise, atorvastatin and ER. Analysis of microRNA-155 expression also suggests its intervention in the regulation of eNOS expression. ER, particularly when combined with atorvastatin, was able to reverse the increase of iNOS and endothelin-1 in high-fat fed rats. CONCLUSIONS: The present results indicate that the association of ER, atorvastatin and exercise is more efficient than isolated interventions in the prevention of endothelial dysfunction.

Capilia™ TB-Neo assay: a new tool for rapid distinction between tuberculous and non-tuberculous mycobacteria.

SETTING: The ability to rapidly distinguish between Mycobacterium tuberculosis complex (MTC) and non-tuberculous mycobacteria (NTM) is critical in clinical practice. OBJECTIVE: To evaluate the usefulness of an immunochromatographic (IC) assay to distinguish between MTC and NTM. DESIGN: We analysed a panel of 145 cultures from 128 patients. The routine molecular identification approaches, such as the AccuProbe™ Mycobacterium tuberculosis complex culture identification test and GenoType(®) Mycobacterium assays, were used as reference methods. RESULTS: Of the 101 positive cultures, 98 were correctly identified using the Capilia™ TB-Neo Assay. Of the three discordant isolates, one was identified as M. bovis bacille Calmette-Guérin (BCG) and two as M. tuberculosis. Although we have not performed the sequencing of these strains, some false-negative results have been described due to mutations in the mpb64 gene or with some M. bovis BCG strains. We did not observe false-positive results or any cross-reaction with 22 NTM strains, 12 non-mycobacterial micro-organisms and 10 negative cultures. CONCLUSION: We report good overall performance (sensitivity 97%, specificity 100%, positive predictive value 100% and negative predictive value 96%) of this rapid assay that is easy to perform and interpret and does not require sample preparation, trained technicians or expensive equipment.

Renal dopaminergic system activity in the rat remnant kidney.

BACKGROUND: Renal dopamine exerts natriuretic and diuretic effects by activating D1-like receptors. Uninephrectomy results in increased renal dopaminergic activity and dopamine-sensitive enhanced natriuresis. METHODS: The present study evaluated renal adaptations in sodium handling and the role of dopamine in rats submitted to (3/4) nephrectomy: right nephrectomy and excision of both poles of the left kidney ((3/4)nx rats). RESULTS: Two weeks after surgery the absolute urinary levels of dopamine were markedly reduced in (3/4)nx rats whereas the urinary dopamine excretion per % of residual nephrons was significantly increased in the remnant kidney of (3/4)nx rats. The V(max) values for renal aromatic L-amino acid decarboxylase, the enzyme responsible for the synthesis of renal dopamine, were decreased in (3/4)nx rats. Renal catechol-O-methyltransferase activity, the enzyme responsible for the methylation of dopamine, was increased in (3/4)nx rats whereas the renal activities of monoamine oxidases A and B did not differ between (3/4)nx and Sham animals. Volume expansion (5% body weight) resulted in similar natriuretic responses in (3/4)nx and Sham rats. During D1 antagonist administration (Sch-23390, 30 microg x h(-1) x kg(-1)) the natriuretic response to volume expansion was reduced in (3/4)nx rats more pronouncedly than in Sham animals. CONCLUSION: The decrease in absolute renal dopamine output in (3/4)nx rats is related with reduced renal synthesis and enhanced O-methylation of the amine. However, this is accompanied in (3/4)nx rats by increased renal dopamine excretion per residual nephrons and dopamine-sensitive enhanced natriuresis.

Beyond central adiposity: liver fat and visceral fat area are associated with metabolic syndrome in morbidly obese patients.

BACKGROUND: Despite its widespread clinical use, both body mass index (BMI) and waist circumference have been reported as inaccurate methods to measure abdominal obesity. The main objective of this study was to determine the relation between visceral fat area and fatty liver infiltration with the expression of metabolic syndrome (MS) in morbidly obese patients. METHODS: We recruited a random selection of 100 morbidly obese patients on pre-operative evaluation for bariatric surgery. A pre-operative CT slice at L4-L5 level, was performed to measure visceral fat and at T12 level to measure hepatic attenuation. RESULTS: Patients with MS had lower hepatic attenuation values (median 49.9 vs 55.5HU; p = .018) and had more VAT (242 vs 172 cm(2);p = .001). Conventional measures (BMI: p = .729 and waist circumference: p = .356), were not useful in discriminating morbidly obese patients with MS. By multivariable logistic regression, fatty liver infiltration (OR = 5.3; p = .03) and age (OR = 1.08; p = .04) were the only factors independently related to the presence of MS. MS prevalence was 100%, 71% and 55%, respectively for patients with both fatty liver and visceral adiposity; one; or none of this findings (AUC - .715; p = .016). CONCLUSION: CT scan seems to measure 2 important markers of MS: visceral adiposity and hepatic fatty infiltration. In morbidly obese patients, both visceral adiposity and hepatic fatty infiltration increase the risk for the presence of MS.

Role of physical exercise on hepatic insulin, glucocorticoid and inflammatory signaling pathways in an animal model of non-alcoholic steatohepatitis.

AIMS: Pro-inflammatory mediators, glucocorticoids and transforming growth factor (TGF)-ß are implicated in the pathogenesis of non-alcoholic steatohepatitis (NASH)-related insulin resistance. As physical activity is beneficial against NASH, we analyzed the voluntary physical activity (VPA) and endurance training (ET) (preventive and therapeutic strategies) effects on hepatic insulin, pro-inflammatory and glucocorticoid signaling regulators/mediators in high-fat (Lieber-DeCarli) diet (HFD)-induced NASH. MAIN METHODS: Adult male Sprague-Dawley rats were divided in standard diet (SD) or HFD, with sedentary, VPA and ET animals in both diet regimens. Plasma glucose and insulin concentrations were analyzed; plasma insulin sensitivity index (ISI) was calculated. Hepatic insulin, pro-inflammatory and glucocorticoid signaling regulators/mediators were evaluated by Western blot or reverse transcriptase-PCR. KEY FINDINGS: ET improved ISI in both diet regimens. HFD-feeding increased interleukin-1ß and induced a similar pattern on interleukin-6 and TGF-ß, which were globally reduced by physical exercise. ET decreased HFD leukemia inhibitory factor level, SD+VPA animals presenting higher values than HFD+VPA animals. HFD increased the ratio of IRS-1(Ser307)/total IRS-1, which was completely mitigated by physical exercise. Physical exercise reduced total ERK and JNK (total and activated) expression in HFD. In SD vs. HFD, VPA presented higher activated JNK and ET presented higher total JNK. Generally, in HFD, the ratio (activated/total) of AKT, and each separately, decreased with exercise and also for activated AKT in SD. Overall, in both diets, exercise reduced 11ß-hydroxysteroid dehydrogenase type 1. ET increased glucocorticoid receptor and reduced PTP1B in HFD. SIGNIFICANCE: Physical exercise mitigates the expression of pro-inflammatory mediators and positively modulates insulin and glucocorticoid signaling in NASH.

Opossum kidney (OK) cells in culture synthesize and degrade the natriuretic hormone dopamine: a comparison with rat renal tubular cells.

To explore further the usefulness of opossum kidney (OK) cells in the study of renal dopaminergic physiology, we have undertaken the study of aromatic L-amino acid decarboxylase (AAAD), catechol-O-methyltransferase (COMT) and type A and B monoamine oxidase (MAO-A and MAO-B), the main enzymes involved in the synthesis and degradation of dopamine. The Vmax values for AAAD, using L-DOPA as the substrate, in rat renal tubular cells were found to be significantly (P < 0.01) higher (120-fold) than in OK cells. However, K(m) values in OK cells (1.1 mM [0.3, 1.9]) were similar to those observed in rat renal tubular cells (K(m) = 1.0 mM [0.8, 1.2]). The Vmax values for COMT (in nmol/mg protein/30 min) in OK cells (2.1 +/- 0.2) were similar to those in the rat renal tubular cells (1.6 +/- 0.1), whereas K(m) values in OK cells (2.3 microM [0.1, 4.5]) differ considerably (4.8-fold, P < 0.01) from those in rat renal tubular cells (11.2 microM [9.2, 13.1]). The Vmax values (in nmol/mg protein/20 min) for deamination of [3H]-5-hydroxytryptamine, the specific MAO-A substrate, was similar in rat renal tubular cells (12.4 +/- 1.0) and OK cells (12.9 +/- 1.1); K(m) values also did not differ between these two preparations. In contrast to rat renal tubular cells, deamination of [14C]-beta-phenylethylamine, the substrate for MAO-B, in OK cells was found to be non-saturable and to represent less than 10% of that observed in homogenates of rat tubular cells. In conclusion, OK cells in culture are endowed with the synthetic and metabolic machinery needed to form and degrade dopamine. The amounts of the enzymes AAAD, COMT and MAO-A found in this cell line are likely to be sufficient to reproduce, under in vitro conditions, the environment in which the renal dopaminergic system normally operates.

Aging, high salt intake, and renal dopaminergic activity in Fischer 344 rats.

The present study examined renal dopaminergic activity and its response to high salt (HS) intake in adult (6-month-old) and old (24-month-old) Fischer 344 rats. Daily urinary excretion of L-3, 4-dihydroxyphenylalanine (L-DOPA), dopamine, and its metabolites 3, 4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid was similar in adult and old rats; by contrast, daily urinary excretion of norepinephrine in old rats was almost twice that in adult animals. HS intake (1% NaCl) over a period of 24 hours resulted in a 2-fold increase in the urinary excretion of dopamine, DOPAC, and norepinephrine in adult animals but not in old animals. Norepinephrine and L-DOPA plasma levels did not change during HS intake and were similar in both groups of rats. The natriuretic response to an HS intake in old rats (from 4.7+/-0.4 to 10.7+/-2.0 nmol. kg(-1). d(-1); Delta=6.0+/-0.9 nmol. kg(-1). d(-1)) was less than in adult rats (from 5.2+/-0.4 to 13.5+/-2.5 nmol. kg(-1). d(-1); Delta=8.3+/-0.8 nmol. kg(-1). d(-1)). A diuretic response to HS intake was observed in adult rats (from 20.9+/-2.3 to 37.6+/-2.8 mL. kg(-1). d(-1)) but not in old rats (from 37.7+/-5.7 to 42.3+/-6. 0 mL. kg(-1). d(-1)). Dopamine levels and dopamine/L-DOPA ratios in the renal cortex of old rats were greater than in adult rats. HS intake increased both dopamine levels and dopamine/L-DOPA ratios in the renal cortex of adult rats but not in old rats. Aromatic L-amino acid decarboxylase activity was higher in old rats than in adult rats; HS intake increased L-amino acid decarboxylase activity (nmol. mg protein(-1). l5 min(-1)) in adult rats (from 67+/-1 to 93+/-1) but not in old rats (from 86+/-2 to 87+/-2). Dopamine inhibited Na(+),K(+)-ATPase activity in proximal tubules obtained from adult rats, but it failed to exert such an inhibitory effect in old rats. It is concluded that renal dopaminergic tonus in old rats is higher than in adult rats but fails to respond to HS intake as observed in adult rats. This may be due in part to the inability of dopamine to inhibit Na(+),K(+)-ATPase activity in old rats.

Influence of maturation and ageing on the biotransformation of noradrenaline in the rat.

The present investigation was undertaken to study the influence of maturation and ageing on the disposition of noradrenaline by the aorta, heart (ventricle), liver and kidney of the rat. Slices of these tissues taken from rats aged less than 18 h, 2.5-3 months or 18-24 months were incubated with 0.1 mumol.l-1 3H-amine during 30 min. At the end of this period, the accumulation of the intact amine in the tissue, as well as the 3H-metabolites formed (3,4-dihydroxyphenylethylglycol, 3,4-dihydroxymandelic acid, normetanephrine and O-methylated deaminated metabolites) were determined by scintillation counting. The results obtained show that in the rat: 1) at any age, noradrenaline is preferentially deaminated; 2) while the capacity of the sympathetic nerve terminals in accumulating noradrenaline is rather well developed at birth, the metabolic system for its degradation is still immature; 3) aldehyde dehydrogenase activity or that of its co-factor (or both) of the heart is apparently missing at birth; 4) removal of noradrenaline by the liver and the kidney did not change with ageing, while that by the aorta decreased and that by the heart increased.

Alpha 1- and alpha 2-adrenoceptors at different levels of the canine saphenous vein.

Presynaptic alpha2- and postsynaptic alpha1-adrenoceptors were compared at the distal and proximal parts of the dog saphenous vein. The results obtained show that: (1) yohimbine is more effective against postsynaptic responses to phenylephrine distally than proximally. On the contrary, WB-4101 is more effective proximally; (2) phenylephrine increases inositol monophosphate production at both levels, but the increase is more pronounced distally; (3) UK-14, 304 and adrenaline reduce and yohimbine and phentolamine increase the release of 3H-noradrenaline caused by electrical stimulation at both levels. However, while adrenaline as well as the antagonists are equipotent at the two levels, UK-14,304 is more potent distally than proximally. In conclusion, we suggest that: more alpha 1A-adrenoceptors exist distally than proximally; imidazoline sites can exist at the distal level which contribute to the higher potency of UK-14,304 distally.

The activity of MAO A and B in rat renal cells and tubules.

The present study reports on the presence of type A and B monoamine oxidase (MAO) activity and their sensitivity to selective MAO-A and MAO-B inhibition by Ro 41-1049 and lazabemide, respectively, in homogenates of isolated rat renal tubules. Non-linear analysis of the saturation curve of H-5-hydroxytryptamine (3H-5-HT ) deamination revealed a Km of 351+/-71 microM (n=4) and a Vmax of 25+/-2 nmol mg protein(-1) h(-1). Deamination of 14C-beta-phenylethylamine (14C-beta-PEA) was also a saturable process yielding Km values of 58+/-12 microM and Vmax values of 24+/-2 nmol mg protein(-1) h(-1). Ro 41-1049 produced a concentration-dependent inhibition of 3H-5-HT deamination with a Ki of 24 nM. Deamination of 14C-beta-PEA was found to be reduced by lazabemide in a concentration-dependent manner with a Ki value of 17 nM. The effect of these selective MAO inhibitors on dopamine fate and DOPAC formation in isolated tubular epithelial cells was also studied. In these studies a clear inhibition of DOPAC formation was observed with Ro 41-1049 (250 nM), while 250 nM lazabemide was found not to increase the accumulation of newly-formed DA in those tubular epithelial cells loaded with 50 microM L-DOPA. In conclusion, the results presented here confirm the presence of both MAO-A and MAO-B activity in renal tubular epithelial cells, that MAO-A is the predominant enzyme involved in the deamination of the natriuretic hormone dopamine and that the deamination of newly-formed dopamine is a time-dependent process which occurs early after the decarboxylation of L-DOPA.

Differential substrate specificity of monoamine oxidase in the rat heart and renal cortex.

Although it is known that substrate specificities differ with species and within each species with the tissues, in the rat heart no natural substrate was found for MAO-B. beta-phenylethylamine (beta-PEA) has always been considered the "endogenous" substrate of MAO B. We thought worthwide to evaluate the effect of Ro 41-1049 and lazabemide, both members of a class of highly selective, mechanism-based and reversible inhibitors for MAO-A and MAO B, respectively on the metabolization of beta-PEA by the rat heart. Also the lack of molecular data on rat heart MAOs, prompted us to better characterize rat heart MAOs, both kinetically and using molecular biology techniques. K(m) values for deamination of beta-PEA in the rat heart were 13-fold those in the kidney, by contrast, K(m) values for deamination of 5-HT were quite similar in both tissues. Unexpectedly, the selective MAO-A inhibitor Ro 41-1049 was by far the most potent inhibitor of beta-PEA (20 microM) deamination in the rat heart, while clorgyline, another MAO A inhibitor, and lazabemide, a MAO B inhibitor, had intermediate efficacy; selegiline was found unable to inhibit deamination of beta-PEA. In the rat renal cortex lazabemide and selegiline both inhibited beta-PEA deamination. The reduction of beta-PEA concentration to just 200 nM, the use of heart membranes instead of tissue homogenates or the use of heart membranes pre-treated with 1% digitonine failed to change this pattern of inhibition. Semicarbazide was found not to alter deamination of beta-PEA. Western blot showed the presence of both isoforms (55 kd and 61 kd) in the renal cortex. In the heart there was a predominance of the A form, the B form being undetected. The RT-PCR products for both MAO-A and MAO-B, were found to have the expected sizes. In conclusion, we found mRNA for MAO-B but were unable to detect the protein itself or its activity when using beta-PEA as the substrate.