Brainstem oxytocinergic modulation of heart rate control in rats: effects of hypertension and exercise training

Oxytocinergic brainstem projections participate in the autonomic control of the circulation. We investigated the effects of hypertension and training on cardiovascular parameters after oxytocin (OT) receptor blockade within the nucleus tractus solitarii (NTS) and NTS OT and OT receptor expression. Male spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats were trained (55% of maximal exercise capacity) or kept sedentary for 3 months and chronically instrumented (NTS and arterial cannulae). Mean arterial blood pressure (MAP) and heart rate (HR) were measured at rest and during an acute bout of exercise after NTS pretreatment with vehicle or OT antagonist (20 pmol of OT antagonist (200 nl of vehicle)-1). Oxytocin and OT receptor were quantified (35S-oligonucleotide probes, in situ hybridization) in other groups of rats. The SHR exhibited high MAP and HR (P < 0.05). Exercise training improved treadmill performance and reduced basal HR (on average -11%) in both groups, but did not change basal MAP. Blockade of NTS OT receptor increased exercise tachycardia only in trained groups, with a larger effect on trained WKY rats (+31 +/- 9 versus +12 +/- 3 beats min-1 in the trained SHR). Hypertension specifically reduced NTS OT receptor mRNA density (-46% versus sedentary WKY rats, P < 0.05); training did not change OT receptor density, but significantly increased OT mRNA expression (+2.5-fold in trained WKY rats and +15% in trained SHR). Concurrent hypertension- and training-induced plastic (peptide/receptor changes) and functional adjustments (HR changes) of oxytocinergic control support both the elevated basal HR in the SHR group and the slowing of the heart rate (rest and exercise) observed in trained WKY rats and SHR.

Development and Application of a Highly Selective Biomimetic Sensor for Detection of Captopril, an Important Ally in Hypertension Control

A biomimetic sensor is proposed as a promising new analytical method for determination of captopril in different classes of samples. The sensor was prepared by modifying a carbon paste electrode with iron (II) phthalocyanine bis(pyridine) [FePe(dipy)] complex. Amperometric measurements in a batch analytical mode were first carried out in order to optimize the sensor response. An applied potential lower than 0.2 V vs Ag vertical bar AgCl in 0.1 mol L(-1) of TRIS buffer at pH 8.0 provided the best response, with a linear range of 2.5 x 10(-5) to 1.7 x 10(-4) mol L(-1). A detailed investigation of the selectivity of the sensor, employing seventeen other drugs, was also performed. Recovery studies were carried out using biological and environment samples in order to evaluate the sensor`s potential for use with these sample classes. Finally, the performance of the biomimetic sensor was optimized in a flow injection (FIA) system using a wall jet electrochemical cell. Under optimized flow conditions, a broad linear response range, from 5.0 x 10(-4) to 2.5 x 10(-2) mol L(-1), was obtained for captopril, with a sensitivity of 210 +/- 1 mu A L mol(-1).

Distribution Of Hydrological Losses For Varying Rainfall And Antecedent Wetness Conditions

Hydrological loss is a vital component in many hydrological models, which are usedin forecasting floods and evaluating water resources for both surface and subsurface flows. Due to the complex and random nature of the rainfall runoff process, hydrological losses are not yet fully understood. Consequently, practitioners often use representative values of the losses for design applications such as rainfall-runoff modelling which has led to inaccurate quantification of water quantities in the resulting applications. The existing hydrological loss models must be revisited and modellers should be encouraged to utilise other available data sets. This study is based on three unregulated catchments situated in Mt. Lofty Ranges of South Australia (SA). The paper focuses on conceptual models for: initial loss (IL), continuing loss (CL) and proportional loss (PL) with rainfall characteristics (total rainfall (TR) and storm duration (D)), and antecedent wetness (AW) conditions. The paper introduces two methods that can be implemented to estimate IL as a function of TR, D and AW. The IL distribution patterns and parameters for the study catchments are determined using multivariate analysis and descriptive statistics. The possibility of generalising the methods and the limitations of this are also discussed. This study will yield improvements to existing loss models and will encourage practitioners to utilise multiple data sets to estimate losses, instead of using hypothetical or representative values to generalise real situations.

Locus de controle e características de personalidade em indivíduos portadores de úlcera e hipertensão: um estudo exploratório

O presente estudo pressupõe que os conceitos de “tensão”, “stress” e “situações geradoras de ansiedade ti, não são suficientes e apropriados, no estágio atual da pesquisa, para explicar em termos de variável antecedente, o aparecimento de distúrbios denominados psicossomáticos. O conceito de Locus de controle, conforme formulado por Rotter é aqui utilizado e investigado, através da Escala Interno-Externo, na medida em que interpretamos situações experimentais, numa série de pesquisas relatadas, como tendo um denomina dor comum: a dificuldade em perceber o controle dos eventos que ocorrem ao sujeito, como dependendo de sua ação. Investigamos também o grau de incidência de distúrbios orgânicos, possíveis diferenças de fatores de personalidade e a associação com a ordem de nascimento. Os dados coletados indicam que portadores de, ulcera e/ou hipertensão tendem a responder mais externamente na Escala I-E, o que reforça nossas interpretações sobre as pesquisas relatadas. Verificou-se ainda que a ordem de nascimento (primogênitos e não primogênitos) está associada com a presença desses distúrbios. Ocorre também, de acordo com nosso instrumento (IDO), uma maior incidência de distúrbios orgânicos nesses' sujeitos. Finalmente, observou-se que, entre os fatores de personalidade investigados somente um distingue sujeitos que são portadores de Úlcera e/ou hipertensão dos que não tem: a tendência ao neuroticismo, que é predominante no grupo experimental.

Effects of hypertension on maternal adaptations to pregnancy: experimental study on spontaneously hypertensive rats

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Combined exercise training in asymptomatic elderly with controlled hypertension: Effects on functional capacity and cardiac diastolic function

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Effect of felodipine on myocardial and renal injury induced by aldosterone-high salt hypertension in uninephrectomized rats

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Doppler Echocardiographic Assessment of Pregnant Women with Chronic Arterial Hypertension

OBJECTIVE: To assess structural and functional cardiac changes in asymptomatic pregnant women with chronic arterial hypertension (CAH). METHODS: One hundred pregnant women with CAH underwent conventional Doppler echocardiography. The Student t test was used to compare them with 29 normotensive pregnant women (NT) in their third gestational trimester. RESULTS: Systolic (SBP; mmHg) and diastolic (DBP; mmHg) blood pressure values were higher (p<0.001) in the CAH pregnant women (SBP: 139±19 and DBP: 92± 18) as compared with those of the NT group (SBP: 112±10 and DBP: 74±9). A significant enlargement of the left atrium (4.10±0.48 cm vs 3.6±0.3 cm; p<0.001) and of the left ventricular normalized mass (59.6±19.7 g/cm2,7 vs 41.9±3.4 g/cm2,7; p<0.001) was observed. Cardiac output (CO, L/min) and systolic volume (SV, mL) were significantly higher in the CAH group (CO: 6.0±1.54 vs 4.9±2.1, p<0.01; SV: 77.3±19.8 vs 56.5±25.8, p<0.001). CONCLUSION: Chronic hypertensive pregnant women have structural and functional cardiac changes that justify routine cardiologic assessment, even in the absence of cardiopulmonary symptoms.

The impact of prior preeclampsia on the risk of superimposed preeclampsia and other adverse pregnancy outcomes in patients with chronic hypertension

OBJECTIVE: We sought to compare the rates of superimposed preeclampsia and adverse outcomes in women with chronic hypertension with or without prior preeclampsia.STUDY DESIGN: We conducted secondary analysis of 369 women with chronic hypertension (104 with prior preeclampsia) enrolled at 12-19 weeks as part of a multisite trial of antioxidants to prevent preeclampsia (no reduction was found). Outcome measures were rates of superimposed preeclampsia and other adverse perinatal outcomes.RESULTS: Prepregnancy body mass index, blood pressure, and smoking status at enrollment were similar between groups. The rates of superimposed preeclampsia (17.3% vs 17.7%), abruptio placentae (1.0% vs 3.1%), perinatal death (6.7% vs 8.7%), and small for gestational age (18.4% vs 14.3%) were similar between groups, but preterm delivery <37 weeks was higher in the prior preeclampsia group (36.9% vs 27.1%; adjusted risk ratio, 1.46; 95% confidence interval, 1.05-2.03; P = .032).CONCLUSION: In women with chronic hypertension, a history of preeclampsia does not increase the rate of superimposed preeclampsia, but is associated with an increased rate of delivery at <37 weeks.

Serum inhibin A and angiogenic factor levels in pregnancies with previous preeclampsia and/or chronic hypertension: are they useful markers for prediction of subsequent preeclampsia?

OBJECTIVE: Our objective was to determine whether measurement of placenta growth factor (PLGF), inhibin A, or soluble fms-like tyrosine kinase-1 (sFlt-1) at 2 times during pregnancy would usefully predict subsequent preeclampsia ( PE) in women at high risk. STUDY DESIGN: We analyzed serum obtained at enrollment (12(0/7) to 19(6/7) weeks) and follow-up (24-28 weeks) from 704 patients with previous PE and/or chronic hypertension (CHTN) enrolled in a randomized trial for the prevention of PE. Logistic regression analysis assessed the association of log-transformed markers with subsequent PE; receiver operating characteristic analysis assessed predictive value. RESULTS: One hundred four developed preeclampsia: 27 at 37 weeks or longer and 77 at less than 37 weeks (9 at less than 27 weeks). None of the markers was associated with PE at 37 weeks or longer. Significant associations were observed between PE at less than 37 weeks and reduced PLGF levels at baseline (P =.022) and follow-up (P <.0001) and elevated inhibin A (P <.0001) and sFlt-1 (P =.0002) levels at follow-up; at 75% specificity, sensitivities ranged from 38% to 52%. Using changes in markers from baseline to follow-up, sensitivities were 52-55%. Associations were observed between baseline markers and PE less than 27 weeks (P <=.0004 for all); sensitivities were 67-89%, but positive predictive values (PPVs) were only 3.4-4.5%. CONCLUSION: Inhibin A and circulating angiogenic factors levels obtained at 12(0/7) to 19(6/7) weeks have significant associations with onset of PE at less than 27 weeks, as do levels obtained at 24-28 weeks with onset of PE at less than 37 weeks. However, because the corresponding sensitivities and/or PPVs were low, these markers might not be clinically useful to predict PE in women with previous PE and/or CHTN.