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1.
Mol Psychiatry ; 22(1): 134-141, 2017 01.
Artigo em Inglês | MEDLINE | ID: mdl-27046647

RESUMO

Norepinephrine released from sympathetic nerves is removed from the neuroeffector junction via the action of the norepinephrine transporter (NET). NET impairment is evident in several clinically important conditions including major depressive disorder (MDD), panic disorder (PD), essential hypertension and the postural orthostatic tachycardia syndrome (POTS). We aimed to determine whether a single nucleotide polymorphism (SNP) in the 3' untranslated region (UTR) of the NET gene is associated with NET impairment and to elucidate the mechanisms involved. The analyses were carried out in two cohorts of European ancestry, which included healthy controls and MDD, PD, hypertensive and POTS patients. Compared with controls, cases had significantly higher prevalence of the T allele of rs7194256 (C/T), arterial norepinephrine, depression and anxiety scores, larger left ventricular mass index, higher systolic and diastolic blood pressures, and heart rate. Bioinformatic analysis identified that the microRNA miR-19a-3p could bind preferentially to the sequence created by the presence of the T allele. This was supported by results of luciferase assays. Compared with controls, cases had significantly lower circulating miR-19a-3p, which was associated with pathways related to blood pressure and regulation of neurotransmission. In vitro norepinephrine downregulated miR-19a-3p. In conclusion, the T allele of the rs7194256 SNP in the 3'UTR of the NET gene is more prevalent in diseases where NET impairment is evident. This might be explained by the creation of a binding site for the microRNA miR-19a-3p. A defect in NET function may potentiate the sympathetic neurochemical signal, predisposing individuals with affective diseases to increased risk of cardiovascular disease development.


Assuntos
Proteínas da Membrana Plasmática de Transporte de Norepinefrina/genética , Regiões 3' não Traduzidas/genética , Adulto , Alelos , Sítios de Ligação , Doenças Cardiovasculares , Estudos de Coortes , Biologia Computacional , Transtorno Depressivo Maior/genética , Hipertensão Essencial , Feminino , Frequência Cardíaca , Humanos , Hipertensão/genética , Masculino , MicroRNAs/genética , Pessoa de Meia-Idade , Norepinefrina/metabolismo , Proteínas da Membrana Plasmática de Transporte de Norepinefrina/metabolismo , Transtorno de Pânico/genética , Polimorfismo de Nucleotídeo Único/genética , Síndrome da Taquicardia Postural Ortostática/genética , População Branca/genética
2.
Diabetes Obes Metab ; 17(1): 91-3, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25200854

RESUMO

There is concern that intentional weight loss may generate excessive loss of fat-free mass (FFM). Idealists target minimal loss of FFM, while others consider that FFM loss of up to 25% of weight loss is acceptable. In a cross-sectional study of 275 weight-stable, overweight or obese adults, we used whole-body dual-energy X-ray absorptiometry to measure FFM. A range of models was used to estimate the expected ΔFFM/Δweight ratio required to attain the body composition of a weight-stable individual at a lower body mass index (BMI). Higher BMI was associated linearly with higher FFM in men and women. Proportional ΔFFM/Δweight was influenced by sex, BMI and age. Direct scatter plot analysis, quadratic curve fit modelling and linear FFM-BMI modelling provided similar estimates for each model of ΔFFM/Δweight ratio, with 40% for men and 33% for women. These results show that the 25% rule is inappropriate and our estimates are higher than those generally reported after intentional weight loss indicating favourable preservation of FFM.


Assuntos
Modelos Biológicos , Desenvolvimento Muscular , Atrofia Muscular/prevenção & controle , Obesidade/terapia , Sobrepeso/terapia , Redução de Peso , Absorciometria de Fóton , Adulto , Composição Corporal , Índice de Massa Corporal , Estudos de Coortes , Estudos Transversais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Atrofia Muscular/diagnóstico por imagem , Atrofia Muscular/etnologia , Atrofia Muscular/etiologia , Inquéritos Nutricionais , Obesidade/diagnóstico por imagem , Obesidade/etnologia , Sobrepeso/diagnóstico por imagem , Sobrepeso/etnologia , Caracteres Sexuais , Estados Unidos , Vitória , Redução de Peso/etnologia , População Branca , Imagem Corporal Total
3.
Diabet Med ; 30(4): e127-34, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23278432

RESUMO

AIM: To assess factors influencing glycaemic control following gastric bypass surgery in patients with Type 2 diabetes and BMI< 30 kg/m(2) . METHODS: Prospective longitudinal study of 103 patients with inadequate glycaemic control who underwent gastric bypass surgery at Soonchunhyang University, Seoul, Korea (n = 66) and Min-Sheng General Hospital, Taipei, Taiwan (n = 37). Procedures were performed August 2009 to January 2011. Key outcome measures were excellent glycaemic control of Type 2 diabetes defined as HbA1c < 42 mmol/mol (≤6%); inadequate response defined as HbA1c > 53 mmol/mol (> 7%). Analysis was conducted using binary logistic regression, and cut-points obtained from receiver operator characteristics. RESULTS: Excellent glycaemic control was achieved in 31 (30%) at 1 year. Diabetes duration of < 7 years and BMI > 27 kg/m(2) provided independent predictors and useful cut-points. Likelihood of excellent glycaemic control for an individual could be estimated using loge (Odds) = -6.7 + (0.26 × BMI) + (-1.2 × diabetes duration). Baseline BMI of < 27 kg/m(2) and baseline C-peptide of < 2.0ng/ml, best predicted a poor glycaemic response. In those with favourable baseline characteristics percentage weight loss (%WL) had a dominant influence on glycaemic outcomes. Baseline C-peptide (> 2.4 ng/ml) and subsequent percentage weight loss (> 16%) were associated with excellent glycaemic control. Higher BMI was associated with greater percentage weight loss. CONCLUSION: In patients with Type 2 diabetes and BMI < 30 kg/m(2) , glycaemic response to gastric bypass is predicted by higher baseline BMI, shorter disease duration and higher fasting C-peptide. Post-surgery weight loss has a dominant effect. Baseline BMI and weight loss have a major influence on outcomes.


Assuntos
Diabetes Mellitus Tipo 2/cirurgia , Derivação Gástrica/métodos , Laparoscopia/métodos , Redução de Peso/fisiologia , Adulto , Idoso , Glicemia/metabolismo , Índice de Massa Corporal , Peptídeo C/metabolismo , Diabetes Mellitus Tipo 2/sangue , Jejum/sangue , Feminino , Hemoglobinas Glicadas/metabolismo , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Resultado do Tratamento , Adulto Jovem
4.
Diabetes Obes Metab ; 14(2): 139-48, 2012 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-21923735

RESUMO

AIM: Insulin resistance and visceral adiposity are predisposing factors for fatty liver disease. The main objectives of this study were (i) to compare the effects of caloric restriction (CR) alone or together with moderate-intensity aerobic exercise training (CR+EX) on liver enzymes, a surrogate marker of liver injury, in obese metabolic syndrome (MetS) subjects and (ii) to identify anthropometric, metabolic, cardiovascular and dietary predictors of changes in liver enzymes. METHODS: Sedentary men and women (n = 63), aged 55 ± 6 (s.d.) years with body mass index 32.7 ± 4.1 kg/m(2) and confirmed MetS, were randomized to 12-week CR, CR+EX or no treatment (Control). RESULTS: Weight loss averaged 7.6% in the CR and 9.1% in the CR+EX group (time effect, p < 0.001; group effect, p = 0.11); insulin sensitivity improved by 49 and 45%, respectively (both p < 0.001). Fitness (maximal oxygen consumption) increased by 19% in the CR+EX group only (p < 0.001). Alanine aminotransferase (ALT) levels decreased by 20% in the CR and 24% in the CR+EX group (time effect, both p < 0.001; group effect, p = 0.68); corresponding values for γ-glutamyltransferase (GGT) were -28 and -33%, respectively (time effect, both p < 0.001; group effect, p = 0.28). Reduction in abdominal fat mass (measured by DXA from L1 to L4) independently predicted ΔALT (r = 0.42, p = 0.005) and ΔGGT (r = 0.55, p < 0.001), whereas change in dietary saturated fat intake was independently associated with ΔALT (r = 0.35, p = 0.03). CONCLUSIONS: Reductions in central adiposity and saturated fat intake are key drivers of improvement in liver enzymes during lifestyle interventions. Exercise training did not confer significant incremental benefits in this study.


Assuntos
Alanina Transaminase/metabolismo , Restrição Calórica , Terapia por Exercício , Fígado Gorduroso/enzimologia , Fígado/enzimologia , Síndrome Metabólica/enzimologia , Obesidade/enzimologia , Redução de Peso , Idoso , Análise de Variância , Restrição Calórica/métodos , Tolerância ao Exercício , Feminino , Humanos , Masculino , Síndrome Metabólica/dietoterapia , Síndrome Metabólica/reabilitação , Pessoa de Meia-Idade , Obesidade/dietoterapia , Obesidade/reabilitação , Consumo de Oxigênio , Comportamento Sedentário
5.
Obes Sci Pract ; 2(1): 13-23, 2016 03.
Artigo em Inglês | MEDLINE | ID: mdl-27812376

RESUMO

OBJECTIVE: The objective of this study was to examine the cross-sectional relationship between the expression of norepinephrine transporter (NET), the protein responsible for neuronal uptake-1, and indices of glycaemia and hyperinsulinaemia, in overweight and obese individuals. METHODS: Thirteen non-medicated, non-smoking subjects, aged 58 ± 1 years (mean ± standard error of the mean), body mass index (BMI) 31.4 ± 1.0 kg m-2, with wide-ranging plasma glucose and haemoglobin A1c (HbA1c, range 5.1% to 6.5%) participated. They underwent forearm vein biopsy to access sympathetic nerves for the quantification of NET by Western blot, oral glucose tolerance test (OGTT), euglycaemic hyperinsulinaemic clamp, echocardiography and assessments of whole-body norepinephrine kinetics and muscle sympathetic nerve activity. RESULTS: Norepinephrine transporter expression was inversely associated with fasting plasma glucose (r = -0.62, P = 0.02), glucose area under the curve during OGTT (AUC0-120, r = -0.65, P = 0.02) and HbA1c (r = -0.67, P = 0.01), and positively associated with steady-state glucose utilization during euglycaemic clamp (r = 0.58, P = 0.04). Moreover, NET expression was inversely related to left ventricular posterior wall dimensions (r = -0.64, P = 0.02) and heart rate (r = -0.55, P = 0.05). Indices of hyperinsulinaemia were not associated with NET expression. In stepwise linear regression analysis adjusted for age, body mass index and blood pressure, HbA1c was an independent inverse predictor of NET expression, explaining 45% of its variance. CONCLUSIONS: Hyperglycaemia is associated with reduced peripheral NET expression. Further studies are required to identify the direction of causality.

6.
Hypertension ; 34(4 Pt 1): 580-5, 1999 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-10523330

RESUMO

To examine the relationship between diet, blood pressure, and plasma insulin concentrations, we studied 14 healthy males who were prescribed low-fat and high-fat diets. The low-fat diet contained 25% (of energy intake) fat and 54% carbohydrate; the high-fat diet was 45% fat (predominantly saturated fat) and 36% carbohydrate. The diets were consumed over consecutive 2-week periods in random sequence, separated by a 2-week washout period. Resting supine systolic and diastolic blood pressures decreased significantly by 7 and 3 mm Hg, respectively, and plasma total cholesterol, LDL cholesterol, and HDL cholesterol concentrations all fell (by 21.6%, 25.7%, and 18.0%, respectively; all P<0.001) on the low-fat compared with the high-fat diet. Fasting glucose and the glucose area under the curve during the frequently sampled intravenous glucose tolerance test (300 mg/kg glucose load with blood sampling for 180 minutes) were significantly lower, and the glucose disappearance rate tended to be faster after the low-fat diet. In contrast, fasting insulin concentrations and the insulin response (insulin area under the curve) to glucose challenge were unchanged. Insulin sensitivity (defined as the rate of glucose disappearance per unit of insulin increase during the period 0 to 40 minutes after the glucose load) was significantly higher on the low-fat diet. These results suggest that the hypotensive effects of a low-fat, high-carbohydrate diet, although associated with an improvement in insulin sensitivity, are not mediated by changes in plasma insulin concentration.


Assuntos
Glicemia/efeitos dos fármacos , Pressão Sanguínea/efeitos dos fármacos , Carboidratos da Dieta/farmacologia , Gorduras na Dieta/farmacologia , Insulina/sangue , Adulto , Área Sob a Curva , Colesterol/sangue , Estudos Cross-Over , Carboidratos da Dieta/administração & dosagem , Carboidratos da Dieta/metabolismo , Gorduras na Dieta/administração & dosagem , Gorduras na Dieta/metabolismo , Jejum/metabolismo , Humanos , Masculino
7.
J Hypertens ; 11(4): 427-37, 1993 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-8390511

RESUMO

OBJECTIVES: To examine the effect of dietary lipid modification on 24-h ambulatory blood pressure, cardiovascular reactivity and sympathetic activity in man. DESIGN: Twenty-four normal volunteers consumed either a high-fat or a low-fat diet for 2 weeks in an open, randomized, crossover study of duration 6 weeks. Diets were isocaloric and balanced for sodium and potassium content. METHODS: Cardiovascular reactivity was assessed by measurement of blood pressure responses to incremental infusions of angiotensin II and noradrenaline, and to sympathetic reflex testing. Plasma noradrenaline spillover and clearance rates were estimated using [3H]-noradrenaline infusion. RESULTS: Total plasma cholesterol and low-density lipoprotein-cholesterol levels both fell significantly on the low-fat compared with the high-fat diet, as did heart rate and mean arterial pressure (recorded by 24-h ambulatory monitoring). These changes were accompanied by reductions in blood pressure responses to cold pressor testing and to noradrenaline infusion on the low-fat diet. Plasma noradrenaline spillover and clearance rates did not change. Post hoc analysis showed an association between oral contraceptive use and increased noradrenaline sensitivity on the high-fat diet among the females tested. CONCLUSION: Dietary fat intake alters heart rate, blood pressure and cardiovascular reactivity to noradrenaline in man without changes in basal noradrenaline metabolism.


Assuntos
Pressão Sanguínea/fisiologia , Gorduras na Dieta/administração & dosagem , Sistema Nervoso Simpático/fisiologia , Adulto , Angiotensina II/farmacologia , Pressão Sanguínea/efeitos dos fármacos , Fenômenos Fisiológicos Cardiovasculares , Sistema Cardiovascular/efeitos dos fármacos , Ácidos Graxos/sangue , Feminino , Frequência Cardíaca/efeitos dos fármacos , Frequência Cardíaca/fisiologia , Humanos , Lipídeos/sangue , Masculino , Pessoa de Meia-Idade , Norepinefrina/sangue , Norepinefrina/farmacologia , Reflexo/fisiologia
8.
J Hypertens ; 16(3): 357-68, 1998 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-9557929

RESUMO

OBJECTIVE: To investigate the interactive effects of oral contraceptive pill use and dietary fat intake on cardiovascular haemodynamics and metabolic parameters in young normotensive women. DESIGN: Thirty-two women participated, of whom 16 were taking oral contraceptive pills (ethinyl-oestradiol plus levonorgestrel) and 16 were age-matched and weight-matched controls not taking such pills. Subjects consumed either a high-fat or a low-fat diet for 2 weeks in an open, randomized, crossover study lasting 6 weeks. Investigations were performed at the end of each diet during the luteal phase of the menstrual cycle. METHODS: Blood pressure was measured by 24 h ambulatory recording; cardiovascular reactivity was determined by examining blood pressure responses to systemic infusions of noradrenaline and angiotensin II and to the cold pressor test; and carbohydrate metabolism was investigated by an intravenous glucose-tolerance test. RESULTS: Plasma triglyceride levels were significantly higher in women taking oral contraceptive pills compared with non-users on both diets; however, responses of lipoprotein levels to the two diets did not differ between study groups (total and low-density lipoprotein cholesterol levels decreased by 15 and 17% in oral contraceptive pill users and by 14% each in non-users, on the low-fat compared with the high-fat diet). Fasting plasma insulin levels, the insulin-production response to administration of glucose (insulin area under the curve) and resting clinic and night-time systolic blood pressures were all significantly reduced on the low-fat diet, but only in non-users. Blood pressure responses to noradrenaline and maximal heart rate response to cold were significantly attenuated during the low-fat diet in oral contraceptive pill users. During the low-fat diet, resting systolic, 24 h systolic and diastolic blood pressures and insulin area under the curve were all significantly higher for women taking the oral contraceptive pills. Users of these pills also exhibited a greater systolic sensitivity to administration both of noradrenaline and of angiotensin II and had a higher plasma renin activity irrespective of dietary phase. CONCLUSIONS: These results confirm that oral contraceptive pills have the potential to cause adverse effects on blood pressure, cardiovascular reactivity and the insulin-production response to administration of glucose and suggest that some of the beneficial effects of a low-fat diet on these parameters may be negated in women taking oral contraceptive pills.


PIP: The interactive effects of combined oral contraceptive (OC) use and dietary fat intake on cardiovascular hemodynamics and metabolic parameters were investigated in a comparative study of 16 normotensive OC users from Australia and 16 age- and weight-matched nonuser controls. The 6-week study's crossover design allocated women to consume either a high- or low-fat diet for 2-week periods. Analyses were performed at the end of each diet during the luteal phase of the menstrual cycle. Plasma triglyceride levels were significantly higher in OC users than nonusers in both diet groups; however, responses of lipoprotein levels to the 2 diets did not differ between study groups. Total and low-density lipoprotein cholesterol levels decreased by 15% and 17%, respectively, in OC users, and by 14% each in non-OC users on the low-fat, compared to the high-fat, diet. Fasting plasma insulin levels, the insulin production response to administration of glucose, and resting clinic and night-time systolic blood pressures were all significantly reduced on the low-fat diet, but only in nonusers. In OC users, blood pressure responses to noradrenaline and maximal heart rate response to cold were significantly attenuated by the low-fat diet. During the low-fat diet, resting systolic, 24-hour systolic, and diastolic blood pressures and areas under the curve were significantly higher in the OC group. OC users also demonstrated a greater systolic sensitivity to administration of both noradrenaline and angiotensin II, and had a higher plasma renin activity, regardless of diet. Overall, these findings confirm that OCs can cause adverse effects on blood pressure, cardiovascular reactivity, and the insulin production response to glucose administration, and negate some of the beneficial effects of a low-fat diet.


Assuntos
Glicemia/metabolismo , Pressão Sanguínea/efeitos dos fármacos , Sistema Cardiovascular/efeitos dos fármacos , Anticoncepcionais Orais/efeitos adversos , Gorduras na Dieta/efeitos adversos , Adulto , Estudos Cross-Over , Dieta com Restrição de Gorduras , Gorduras na Dieta/administração & dosagem , Feminino , Teste de Tolerância a Glucose , Frequência Cardíaca , Humanos , Insulina/sangue , Lipídeos/sangue , Norepinefrina/sangue , Renina/sangue , Triglicerídeos/sangue
9.
Am J Cardiol ; 75(8): 582-6, 1995 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-7887382

RESUMO

This study was conducted to examine the effects of short-term cholesterol reduction on cardiovascular reactivity in mildly hypertensive patients. Seven male and 7 female patients, aged 34 to 68 years, received pravastatin (40 mg/day) or matched placebo for 3 weeks in a randomized, double-blind, crossover study. Cardiovascular reactivity was assessed by measurement of blood pressure (BP) responses to incremental infusions of angiotensin II and norepinephrine, by cold pressor testing and isometric exercise. Compared with placebo, pravastatin caused significant reductions in plasma total and low-density lipoprotein cholesterol levels, which averaged 20% and 31%, respectively (both p < 0.0001), and in diastolic BP responses (expressed as the infusion rate required to raise BP by 20 mm Hg) to both angiotensin II (7.3 +/- 3.0 vs 9.7 +/- 4.7 ng/kg/min, p = 0.05) and norepinephrine (0.15 +/- 0.13 vs 0.38 +/- 0.33 micrograms/kg/min, p = 0.03). Systolic BP responses were similar with both treatments. Body weight, resting BP, and maximal BP responses to physical stressors were similar with each treatment.


Assuntos
Angiotensina II/efeitos dos fármacos , Sistema Cardiovascular/efeitos dos fármacos , Hipercolesterolemia/fisiopatologia , Hipertensão/fisiopatologia , Norepinefrina/antagonistas & inibidores , Pravastatina/farmacologia , Adulto , Idoso , Pressão Sanguínea/efeitos dos fármacos , Sistema Cardiovascular/fisiopatologia , Colesterol/sangue , Estudos Cross-Over , Método Duplo-Cego , Feminino , Humanos , Hipercolesterolemia/complicações , Hipercolesterolemia/tratamento farmacológico , Hipertensão/complicações , Masculino , Pessoa de Meia-Idade , Pravastatina/uso terapêutico , Resultado do Tratamento
10.
Acta Physiol (Oxf) ; 212(1): 39-48, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-25041756

RESUMO

AIM: Hypertension is a major clinical complication of obesity. Our previous studies show that abnormal uptake of the nitric oxide precursor L-arginine, via the cationic amino acid transporter-1 (CAT1), contributes to endothelial dysfunction in cardiovascular disease. In this study, we tested the hypothesis that abnormal L-arginine transport may be a key mediator of obesity-induced hypertension. METHODS: Mean arterial pressure (MAP) was monitored by telemetry in conscious wild-type (WT; n = 13) mice, and transgenic mice with endothelial-specific overexpression of CAT1 (CAT+; n = 14) fed a normal or a high fat diet for 20 weeks. Renal angiotensin II (Ang II), CAT1 mRNA and plasma nitrate/nitrite levels were then quantified. In conjunction, plasma nitrate/nitrite levels were assessed in obese normotensive (n = 15) and obese hypertensive subjects (n = 15). RESULTS: Both genotypes of mice developed obesity when fed a high fat diet (P ≤ 0.002). Fat fed WT mice had 13% greater MAP and 78% greater renal Ang II content, 42% lesser renal CAT1 mRNA levels and 42% lesser plasma nitrate/nitrite levels, than WT mice fed a normal fat diet (P ≤ 0.02). In contrast, none of these variables were significantly altered by high fat feeding in CAT+ mice (P ≥ 0.36). Plasma nitrate/nitrite levels were 17% less in obese hypertensives compared with obese normotensives (P = 0.02). CONCLUSION: Collectively, these data indicate that obesity-induced down-regulation of CAT1 expression and subsequent reduced bioavailability of nitric oxide may contribute to the development of obesity-induced hypertension.


Assuntos
Arginina/metabolismo , Canais de Cálcio/metabolismo , Células Endoteliais/metabolismo , Hipertensão/etiologia , Obesidade/complicações , Canais de Cátion TRPV/metabolismo , Idoso , Animais , Dieta Hiperlipídica/efeitos adversos , Feminino , Humanos , Hipertensão/metabolismo , Masculino , Camundongos , Camundongos Transgênicos , Pessoa de Meia-Idade , Óxido Nítrico/metabolismo , Obesidade/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa
11.
Br J Clin Pharmacol ; 44(4): 319-24, 1997 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-9354305

RESUMO

The observation that relatively short periods of cholesterol lowering therapy can reduce the incidence of coronary artery disease events has prompted interest in the short term effects of lipoproteins on cardiovascular responsiveness. Numerous studies in animals and humans have demonstrated that oxidized LDL-cholesterol can impair endothelial dependent vasodilation in coronary arteries and peripheral resistance vessels. Reduction of plasma LDL-cholesterol levels in hypercholesterolaemic patients improves nitric oxide mediated vasodilator responses in the coronary and peripheral circulation. LDL-cholesterol also potentiates responses to vasoconstrictors such as noradrenaline and endothelin-1 in the absence of endothelium, possibly by enhancing calcium influx into vascular smooth muscle cells. Pharmacological reduction of plasma LDL-cholesterol levels has been shown to reduce blood pressure responses to intravenous infusions of pressor hormones and to stress. However, the relative contribution of changes in endothelial dependent vasodilation and vasoconstrictor or inotropic responses remains to be established. Short term changes in LDL-cholesterol produce changes in cardiovascular responsiveness that may influence the development of ischaemic events.


Assuntos
LDL-Colesterol/sangue , Vasos Coronários/fisiopatologia , Hipercolesterolemia/fisiopatologia , Lipoproteínas/fisiologia , Vasoconstrição/fisiologia , Vasodilatação/fisiologia , Animais , Anticolesterolemiantes/uso terapêutico , Ensaios Clínicos como Assunto , Humanos , Hipercolesterolemia/sangue , Hipercolesterolemia/tratamento farmacológico , Pravastatina/uso terapêutico
12.
Blood Press ; 6(2): 96-102, 1997 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-9105648

RESUMO

To examine the effects of short-term dietary lipid modification on alpha- and beta-adrenoceptor-mediated cardiovascular responsiveness, 19 normal volunteers consumed either a high-fat or a low-fat diet for 2 weeks in an open, randomized, crossover study of 6 weeks' duration. Diets were balanced for sodium and potassium content. Adrenoceptor-mediated cardiovascular responsiveness was assessed by measuring blood pressure and heart rate responses to incremental infusions of phenylephrine and isoprenaline. Baroreflexes were studied by examining heart rate responses to phenylephrine and to the Valsalva manoeuvre. Total plasma cholesterol and low-density lipoprotein cholesterol levels both fell significantly (by 22% and 26%, respectively), on the low-fat compared with the high-fat diet, as did resting supine blood pressures and heart rate (by 6 mmHg systolic and 3 mmHg diastolic, and 5 beats/min). These changes were accompanied by a significant reduction in the systolic blood pressure response to isoprenaline. Blood pressure responses to phenylephrine and baroreflex sensitivity did not change. These results suggest that dietary fat intake alters cardiac beta-adrenergic reactivity without significant effects on vascular alpha-adrenoceptor mediated responses or baroreflexes.


Assuntos
Barorreflexo/fisiologia , Fenômenos Fisiológicos Cardiovasculares , Dieta com Restrição de Gorduras , Receptores Adrenérgicos alfa/fisiologia , Receptores Adrenérgicos beta/fisiologia , Adulto , Pressão Sanguínea/efeitos dos fármacos , Peso Corporal , Estudos Cross-Over , Feminino , Frequência Cardíaca/efeitos dos fármacos , Humanos , Isoproterenol/farmacologia , Lipídeos/sangue , Masculino , Fenilefrina/farmacologia , Valores de Referência , Urina/química
13.
Clin Exp Pharmacol Physiol ; 26(8): 656-60, 1999 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-10474783

RESUMO

1. Hypercholesterolaemia has been associated with decreased heart rate variability, a measure of cardiac parasympathetic activity. However, the effect of perturbation of the lipid profile on autonomic function has not been examined systematically. 2. The effects of short-term dietary lipid modification on autonomic function are studied in 25 normotensive, non-smoking, premenopausal women with normal bodyweight. Subjects consumed either a low (L, 25%) or high fat (H, 40%) diet for 2 weeks in an open, randomized, cross-over manner with a 2 week washout. 3. Baroreflex sensitivity was determined by gating beat-to-beat heart period (RR) interval and continuous non-invasive blood pressure recordings. Heart rate variability measures of cardiac parasympathetic nervous system activity were obtained in the time (standard deviation of RR intervals, root mean square of successive differences (rMSSD)) and frequency (high frequency power) domains. All assessments were made at the same timepoint in the menstrual cycle. 4. Both low-density lipoprotein-cholesterol and high-density lipoprotein-cholesterol decreased significantly (P < 0.05) with increased dietary fat intake (H, 2.7 +/- 0.1 vs L, 2.2 +/- 0.1; H, 1.3 +/- 0.1 vs L, 1.1 +/- 0.1 mmol/L, respectively) as did mean arterial pressure (H, 78.1 +/- 1.5 vs L, 74.3 +/- 1.5 mmHg). Weight was unchanged by dietary lipid intake (H, 62.6 +/- 8.5 vs L, 62.3 +/- 8.3 kg, P = NS). 5. There was a significant increase in rMSSD (H, 29.6 +/- 3.4 vs L, 38.8 +/- 6.4 msec, P < 0.05) and natural logarithm of high frequency power following low fat diet (H, 4.4 +/- 0.2 vs L, 4.8 +/- 0.3 msec2, P = 0.01). Baroreflex sensitivity also increased following the low fat diet (H, 13.91 +/- 2.2 vs L, 16.9 +/- 3.2 msec/mmHg, P = 0.23). 6. Short-term dietary lipid modification can significantly increase cardiac parasympathetic nervous system activity in healthy premenopausal women. These changes in autonomic status appear to be independent of changes in bodyweight and may be of clinical relevance considering the prognostic implications of heart rate variability in cardiovascular disease.


Assuntos
Gorduras na Dieta/farmacologia , Sistema Nervoso Parassimpático/efeitos dos fármacos , Adolescente , Adulto , Barorreflexo/efeitos dos fármacos , Pressão Sanguínea/efeitos dos fármacos , Peso Corporal/efeitos dos fármacos , Estudos Cross-Over , Feminino , Humanos , Lipídeos/sangue , Pessoa de Meia-Idade , Sistema Nervoso Parassimpático/fisiologia , Pré-Menopausa , Fatores de Tempo
14.
Blood Press ; 7(5-6): 277-81, 1998 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-10321439

RESUMO

The mean blood pressure (BP) can be accurately estimated from indirect measurements of brachial artery pressure, i.e. mean BP = diastolic BP + 1/3 pulse pressure. Although this equation has been used as a surrogate of mean systemic pressure, it is unknown whether this approximation can be validly applied to distal vascular beds. Therefore we determined the accuracy of this method as an estimate of the mean pressure in distal arteries by measuring finger BP with the Finapres device in 16 normotensive and 12 hypertensive subjects. The "calculated" and measured values of mean BP were compared when subjects were resting and during manoeuvres which aimed to alter the shape of the pulse waveform. Although closely correlated with the measured value, the "calculated" resting mean BP was systematically greater (+2.7+/-0.7 mm Hg, p<0.001). Additionally, the rise in the mean pressure produced by infusion of phenylephrine, an alpha1-adrenoceptor stimulant (16.0+/-1.5 mm Hg) was underestimated by the calculation (13.1+/-1.5 mm Hg, p<0.05). Of even greater concern was that calculating the mean pressure during infusion of isoprenaline (a beta-adrenergic stimulant) suggested the mean pressure had increased by 5.8+/-1.6 mm Hg when it had actually fallen (-2.1+/-2.4 mm Hg, p<0.001 vs. the measured value). Thus, calculating the mean BP from Finapres measurements roughly approximates the measured value when subjects are at rest. However, this estimation becomes inaccurate when pulse wave dimensions are altered, and is probably unsuitable for assessing the acute effects of vasoactive drugs, in particular vasodilators, on BP.


Assuntos
Determinação da Pressão Arterial/métodos , Dedos/irrigação sanguínea , Agonistas Adrenérgicos beta/farmacologia , Braço/irrigação sanguínea , Erros de Diagnóstico , Feminino , Humanos , Isoproterenol/farmacologia , Masculino , Pessoa de Meia-Idade , Fenilefrina/farmacologia , Valores de Referência , Fluxo Sanguíneo Regional/efeitos dos fármacos , Fluxo Sanguíneo Regional/fisiologia , Reprodutibilidade dos Testes , Vasoconstritores/farmacologia
15.
Med J Aust ; 155(10): 691-2, 694, 698-700, 1991 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-1943901

RESUMO

OBJECTIVE: To describe the outcome of the management of cardiovascular risk factors in the hypertension clinic of a teaching hospital over a five-year period. DESIGN: Retrospective analysis of risk factor data (blood pressure, plasma cholesterol level, body weight, smoking and drinking habits) obtained from computerised hypertension clinic progress report forms. SETTING: Public teaching hospital. PATIENTS: One hundred and thirty-one patients referred to the clinic from both general practice and from within the hospital who attended the clinic regularly during the five-year study period. INTERVENTION: Long term management of hypertension and coexisting coronary risk factors by dietary, medical and lifestyle intervention. RESULTS: There was a significant improvement in diastolic blood pressure control in 1990 versus 1986 in both men and women, while systolic blood pressure improved in women only. The number of patients controlled with monotherapy increased from 38% in 1986 to 45% in 1990. Eighty-nine per cent of the men and 85% of women remained above their maximum desirable weight. Reported levels of alcohol consumption were low and the proportion of smokers was below that of the general population. A significant decline in plasma total cholesterol levels was observed in the women. Despite dietary advice and a limited use of lipid lowering drugs, 53.2% of the men and 66.1% of the women continued to have total plasma cholesterol levels above 5.5 mmol/L in 1990. High density lipoprotein levels increased significantly in the women only. CONCLUSION: A high proportion of our clinic patients have well controlled hypertension, but the clinic program produced little evidence of improvement in risk factors in men stabilised by long term therapy. More intensive methods of achieving lifestyle modification and a wider use of lipid lowering drugs may be needed if we are to achieve satisfactory body weights and lipid profiles in hypertensive patients.


Assuntos
Instituições de Assistência Ambulatorial , Doença das Coronárias/prevenção & controle , Hipertensão/tratamento farmacológico , Pressão Sanguínea , Peso Corporal , Colesterol/sangue , Feminino , Humanos , Hipertensão/fisiopatologia , Masculino , Fatores de Risco , Fumar
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