Fixed-dose combination of nifedipine gastrointestinal therapeutic system and candesartan cilexetil in patients with moderate-to-severe essential hypertension: an open-label, long-term safety and efficacy study.

WHAT IS KNOWN AND OBJECTIVE: The nifedipine gastrointestinal therapeutic system (GITS)/candesartan cilexetil (N/C) combination was demonstrated to be an effective, well-tolerated antihypertensive therapy in a short-term study. The current study investigated the long-term safety and efficacy of a fixed-dose combination (FDC) of N/C therapy in moderate-to-severe essential hypertension. METHODS: A multinational, 70-centre, open-label study of N/C treatment for 28 or 52 weeks at a target dose of N60 mg/C32 mg. The primary assessment included the incidence of treatment-emergent adverse events (TEAEs). Efficacy assessments included change from baseline in systolic and diastolic blood pressure (BP). RESULTS AND DISCUSSION: A total of 508 patients were enrolled, with 417 (82·1%) completing week 28 of treatment. Of these, 200 patients continued treatment, as planned, to week 52, with 193 (96·5%) completing this period. At least one TEAE or drug-related TEAE were reported in 76·8% and 45·3% patients up to week 28, and in 80·7% and 46·9% up to week 52/end of study. Most TEAEs and drug-related TEAEs to week 52 (93·9% and 95·4%, respectively) were mild or moderate in intensity. Rates of drug-related serious AEs were low (0·6%). TEAE-related discontinuations occurred in 10% patients before week 28 and in no additional patients thereafter. N/C provided substantial, sustained reductions in mean systolic and diastolic BP from baseline: 30·1 ± 18·4 and 12·8 ± 10·7 mmHg, respectively, at week 52. WHAT IS NEW AND CONCLUSIONS: Nifedipine GITS/candesartan cilexetil FDC at the target dose of 60 mg/32 mg was well tolerated for a study duration up to 52 weeks and provided sustained reductions in systolic and diastolic BP.

Structural and electro-anatomical characterization of the equine pulmonary veins: implications for atrial fibrillation.

INTRODUCTION/OBJECTIVES: Spontaneous pulmonary vein (PV) activity triggers atrial fibrillation (AF) in humans. Although AF frequently occurs in horses, the origin remains unknown. This study investigated the structural and electro-anatomical properties of equine PVs to determine the potential presence of an arrhythmogenic substrate. ANIMALS, MATERIALS AND METHODS: Endocardial three-dimensional electro-anatomical mapping (EnSite Precision) using high-density (HD) catheters was performed in 13 sedated horses in sinus rhythm. Left atrium (LA) access was obtained retrogradely through the carotid artery. Post-mortem, tissue was harvested from the LA, right atrium (RA), and PVs for histological characterization and quantification of ion channel expression using immunohistochemical analysis. RESULTS: Geometry, activation maps, and voltage maps of the PVs were created and a median of four ostia were identified. Areas of reduced conduction were found at the veno-atrial junction. The mean myocardial sleeve length varied from 28 ± 13 to 49 ± 22 mm. The PV voltage was 1.2 ± 1.4 mV and lower than the LA (3.4 ± 0.9 mV, P < 0.001). The fibrosis percentage was higher in PV myocardium (26.1 ± 6.6%) than LA (14.5 ± 5.0%, P = 0.003). L-type calcium channel (CaV1.2) expression was higher in PVs than LA (P = 0.001). T-type calcium channels (CaV3.3), connexin-43, ryanodine receptor-2, and small conductance calcium-activated potassium channel-3 was expressed in PVs. CONCLUSIONS: The veno-atrial junction had lower voltages, increased structural heterogeneity and areas of slower conduction. Myocardial sleeves had variable lengths, and a different ion channel expression compared to the atria. Heterogeneous properties of the PVs interacting with the adjacent LA likely provide the milieu for re-entry and AF initiation.

In-treatment HDL cholesterol levels and development of new diabetes mellitus in hypertensive patients: the LIFE Study.

AIMS: Although hypertensive patients with low baseline HDL cholesterol levels have a higher incidence of diabetes mellitus, whether changing levels of HDL over time are more strongly related to the risk of new diabetes in hypertensive patients has not been examined. METHODS: Incident diabetes mellitus was examined in relation to baseline and in-treatment HDL levels in 7485 hypertensive patients with no history of diabetes randomly assigned to losartan- or atenolol-based treatment. RESULTS: During 4.7 ± 1.2 years follow-up, 520 patients (6.9%) developed new diabetes. In univariate Cox analyses, compared with the highest quartile of HDL levels (> 1.78 mmol/l), baseline and in-treatment HDL in the lowest quartile (< 1.21 mmol/l) identified patients with > 5-fold and > 9 fold higher risks of new diabetes, respectively; patients with baseline or in-treatment HDL in the 2nd and 3rd quartiles had intermediate risk of diabetes. In multivariable Cox analyses, adjusting for randomized treatment, age, sex, race, prior anti-hypertensive therapy, baseline uric acid, serum creatinine and glucose entered as standard covariates, and in-treatment non-HDL cholesterol, Cornell product left ventricular hypertrophy, diastolic and systolic pressure, BMI, hydrochlorothiazide and statin use as time-varying covariates, the lowest quartile of in-treatment HDL remained associated with a nearly 9-fold increased risk of new diabetes (hazard ratio 8.7, 95% CI 5.0-15.2), whereas the risk of new diabetes was significantly attenuated for baseline HDL < 1.21 mmol/l (hazard ratio 3.9, 95% CI 2.8-5.4). CONCLUSIONS: Lower in-treatment HDL is more strongly associated with increased risk of new diabetes than baseline HDL level.

Low-grade systolic murmurs in healthy middle-aged individuals: innocent or clinically significant? A 35-year follow-up study of 2014 Norwegian men.

OBJECTIVE: To determine whether a low-grade systolic murmur, found at heart auscultation, in middle-aged healthy men influences the long-term risk of aortic valve replacement (AVR) and death from cardiovascular disease (CVD). Setting and subjects. During 1972-1975, 2014 apparently healthy men aged 40-59 years underwent an examination programme including case history, clinical examination, blood tests and a symptom-limited exercise ECG test. Heart auscultation was performed under standardized conditions, and murmurs were graded on a scale from I to VI. No men were found to have grade V/VI murmurs. Participants were followed for up to 35 years. RESULTS: A total of 1541 men had no systolic murmur; 441 had low-grade murmurs (grade I/II) and 32 had moderate-grade murmurs (grade III/IV). Men with low-grade murmurs had a 4.7-fold [95% confidence interval (CI) 2.1-11.1] increased age-adjusted risk of AVR, but no increase in risk of CVD death. Men with moderate-grade murmurs had an 89.3-fold (95% CI 39.2-211.2) age-adjusted risk of AVR and a 1.5-fold (95% CI 0.8-2.5) age-adjusted increased risk of CVD death. CONCLUSIONS: Low-grade systolic murmur was detected at heart auscultation in 21.9% of apparently healthy middle-aged men. Men with low-grade murmur had an increased risk of AVR, but no increase in risk of CVD death. Only 1.6% of men had moderate-grade murmur; these men had a very high risk of AVR and a 1.5-fold albeit non-significant increase in risk of CVD death.

Clustered metabolic abnormalities blunt regression of hypertensive left ventricular hypertrophy: the LIFE study.

BACKGROUND AND AIMS: Clusters of metabolic abnormalities resembling phenotypes of metabolic syndrome predicted outcome in the LIFE study, independently of single risk markers, including obesity, diabetes and baseline ECG left ventricular hypertrophy (LVH). We examined whether clusters of two or more metabolic abnormalities (MetAb, including obesity, high plasma glucose without diabetes, low HDL-cholesterol) in addition to hypertension were associated to levels of ECG LVH reduction comparable to that obtained in hypertensive subjects without or with only one additional metabolic abnormality (no-MetAb). METHODS AND RESULTS: We studied 5558 non-diabetic participants without MetAb (2920 women) and 1235 with MetAb (751 women) from the LIFE-study cohort. MetAb was defined by reported LIFE criteria, using partition values from the ATPIII recommendations. Time-trends of Cornell voltage-duration product (CP) over 5 years was assessed using a quadratic polynomial contrast, adjusting for age, sex, prevalent cardiovascular disease and treatment arm (losartan or atenolol). At baseline, despite similar blood pressures, CP was greater in the presence than in the absence of MetAb (p<0.0001). During follow-up, despite similar reduction of blood pressure, CP decreased less in patients with than in those without MetAb, even after adjustment for the respective baseline values (both p<0.002). Losartan was more effective than atenolol in reducing CP independently of MetAb. CONCLUSIONS: Clusters of metabolic abnormalities resembling phenotypes of metabolic syndrome are related to greater initial ECG LVH in hypertensive patients with value of blood pressure similar to individuals without metabolic abnormalities, and are associated with less reduction of ECG LVH during antihypertensive therapy, potentially contributing to the reported adverse prognosis of metabolic syndrome.

Predictors of new-onset diabetes mellitus in hypertensive patients: the VALUE trial.

Diabetes mellitus often develops in patients with hypertension. We investigated predictors of diabetes mellitus development in hypertensives at risk of developing the disease in the VALUE trial population. Among the 9995 non-diabetic hypertensive patients at baseline, 1298 patients developed diabetes mellitus during the average follow-up of 4.2 years. New-onset diabetes mellitus was defined from adverse event reports, information about new antidiabetic medication and/or a fasting glucose >or=7.0 mmol l(-1) at the end of trial. Twenty-five potential baseline predictors of new-onset diabetes mellitus were analysed by univariate logistic regression and 14 of 25 predictors were found to be statistically significant with a P-value <0.05. The predictors were in order of decreasing significance; glucose, body mass index (BMI), age, uric acid, non-Caucasian race, haemoglobin, heart rate, randomized study treatment, history of coronary heart disease (CHD), gender, total cholesterol, proteinuria, potassium and creatinine. Multivariate stepwise logistic regression analyses were used and potential baseline predictors of new-onset diabetes mellitus were considered significant by four different models (P-value <0.001). The final multivariate model selected included all patients, but not treatment group as a potential predictor, and the six significant predictors identified from this model were glucose, BMI, non-Caucasian race, age, heart rate and history of CHD. In conclusion, glucose and BMI were the most important predictors of new-onset diabetes mellitus in hypertensive patients at high cardiovascular risk, and easily accessible clinical characteristics strongly predict patients at risk of developing diabetes mellitus.

Achieving blood pressure goals globally: five core actions for health-care professionals. A worldwide call to action.

The prevalence of hypertension continues to rise across the world, and most patients who receive medical intervention are not adequately treated to goal. A Working Group including representatives of nine international health-care organizations was convened to review the barriers to more effective blood pressure control and propose actions to address them. The group concluded that tackling the global challenge of hypertension will require partnerships among multiple constituencies, including patients, health-care professionals, industry, media, health-care educators, health planners and governments. Additionally, health-care professionals will need to act locally with renewed impetus to improve blood pressure goal rates. The Working Group identified five core actions, which should be rigorously implemented by practitioners and targeted by health systems throughout the world: (1) detect and prevent high blood pressure; (2) assess total cardiovascular risk; (3) form an active partnership with the patient; (4) treat hypertension to goal and (5) create a supportive environment. These actions should be pursued with vigour in accordance with current clinical guidelines, with the details of implementation adapted to the economic and cultural setting.

Tissue Doppler imaging describes diastolic function in men prone to develop hypertension over twenty years.

AIMS: Hypertension is one of several risk factors of cardiovascular disease and is associated with left ventricular (LV) systolic and diastolic dysfunction. A method for reliably detecting the onset of LV dysfunction before transition to irreversible damage of the myocardium would be of crucial importance in subjects with essential hypertension. METHODS AND RESULTS: Subjects with clear differences in BP level, development and duration of the hypertensive disease were examined at the age of 60 yrs: normotensives (n = 17), new hypertensives who developed hypertension over a 20 year period (n = 15) and hypertensives (n = 19). Relationships between conventional echocardiographic and tissue velocities imaging (TVI) parameters compared to LV parameters, and TVI as an estimate of LV function were explored. E'(Lat) (TVI peak early diastolic velocity) (P = 0.006) and E/E'(Lat) (P = 0.002) demonstrated differences in diastolic function between the groups. There were no significant differences regarding systolic myocardial velocities. E'(Lat) correlated to S'(Lat) (TDI peak systolic velocity) (r = 0.32, P = 0.026) and was independently predicted by S'(Lat) (R(2) = 0.24, P = 0.025) in multivariate analysis. E'(Lat) correlated negatively to LV mass index (r = -0.34, P = 0.012), also in multivariate regression analysis (R(2) = 0.12, P = 0.032). CONCLUSIONS: Myocardial diastolic velocities and mitral flow to annulus velocity ratio differentiated LV function between the hypertensive and normotensive groups. The parameters probably reflect changes in relaxation, recoil and contraction and parallel changes in LV mass index.

Risk of diabetes in a real-world setting among patients initiating antihypertensive therapy with valsartan or amlodipine.

In the Valsartan Antihypertensive Long-Term Use Evaluation (VALUE) trial, the risk of new-onset diabetes was reported to be 23% lower among patients initiating therapy with valsartan versus amlodipine. The objective of our study was to examine whether this finding is generalizable to 'real-world' clinical practice. A retrospective cohort design and a large US health insurance database were employed for analyses. Study subjects included all hypertensive patients, aged >or=35 years, who were free from diabetes and who initiated treatment with valsartan (n=9999) or amlodipine (n=18 698) between January 1999 and March 2005. Unadjusted absolute risks of diabetes were 21.4 (95% confidence interval (CI) 18.9-24.3) and 26.3 (95% CI 24.3-28.3) per 1000 patient-years for valsartan and amlodipine, respectively; the corresponding relative risk (RR) for valsartan was 0.82 (95% CI 0.70-0.94). Multivariate analyses - controlling for age, sex, presence of hypercholesterolemia, cardiovascular disease and kidney disease, and pretreatment medical care expenditures - yielded similar results (RR=0.79, 95% CI 0.68-0.92). Our study thus corroborates the finding from VALUE that diabetes risk is lower for patients who receive valsartan versus amlodipine, and extends this finding to a 'real-world' setting.

Clusters of metabolic risk factors predict cardiovascular events in hypertension with target-organ damage: the LIFE study.

The relation of metabolic syndrome (MetS) with cardiovascular outcome may be less evident when preclinical cardiovascular disease is present. We explored, in a post hoc analysis, whether MetS predicts cardiovascular events in hypertensive patients with electrocardiographic left ventricular hypertrophy (ECG-LVH) in the Losartan Intervention For Endpoint (LIFE) reduction in hypertension study. MetS was defined by >or=2 risk factors plus hypertension: body mass index >or=30 kg/m(2), high-density lipoprotein (HDL)-cholesterol <1.0/1.3 mmol/l (<40/50 mg/dl) (men/women), glucose >or=6.1 mmol/l (>or=110 mg/dl) fasting or >or=7.8 mmol/l (>or=140 mg/dl) nonfasting or diabetes. Cardiovascular death and the primary composite end point (CEP) of cardiovascular death, stroke and myocardial infarction were examined. In MetS (1,591 (19.3%) of 8,243 eligible patients), low HDL-cholesterol (72%), obesity (77%) and impaired glucose (73%) were similarly prevalent, with higher blood pressure, serum creatinine and Cornell product, but lower Sokolow-Lyon voltage (all P<0.001). After adjusting for baseline covariates, hazard ratios for CEPs and cardiovascular death (4.8+/-1.1 years follow-up) were 1.47 (95% confidence interval (CI), 1.27-1.71)- and 1.73 (95% CI, 1.38-2.17)-fold higher with MetS (both P<0.0001), and were only marginally reduced when further adjusted for diabetes, obesity, low HDL-cholesterol, non-HDL-cholesterol, pulse pressure and in-treatment systolic blood pressure and heart rate. Thus, MetS is associated with increased cardiovascular events in hypertensive patients with ECG-LVH, independently of single cardiovascular risk factors.

Blood pressure-lowering effects of nifedipine/candesartan combinations in high-risk individuals: subgroup analysis of the DISTINCT randomised trial.

The DISTINCT study (reDefining Intervention with Studies Testing Innovative Nifedipine GITS-Candesartan Therapy) investigated the efficacy and safety of nifedipine GITS/candesartan cilexetil combinations vs respective monotherapies and placebo in patients with hypertension. This descriptive sub-analysis examined blood pressure (BP)-lowering effects in high-risk participants, including those with renal impairment (estimated glomerular filtration rate<90 ml min-1, n=422), type 2 diabetes mellitus (n=202), hypercholesterolaemia (n=206) and cardiovascular (CV) risk factors (n=971), as well as the impact of gender, age and body mass index (BMI). Participants with grade I/II hypertension were randomised to treatment with nifedipine GITS (N) 20, 30, 60 mg and/or candesartan cilexetil (C) 4, 8, 16, 32 mg or placebo for 8 weeks. Mean systolic BP and diastolic BP reductions after treatment in high-risk participants were greater, overall, with N/C combinations vs respective monotherapies or placebo, with indicators of a dose-response effect. Highest rates of BP control (ESH/ESC 2013 guideline criteria) were also achieved with highest doses of N/C combinations in each high-risk subgroup. The benefits of combination therapy vs monotherapy were additionally observed in patient subgroups categorised by gender, age or BMI. All high-risk participants reported fewer vasodilatory adverse events in the pooled N/C combination therapy than the N monotherapy group. In conclusion, consistent with the DISTINCT main study outcomes, high-risk participants showed greater reductions in BP and higher control rates with N/C combinations compared with respective monotherapies and lesser vasodilatory side-effects compared with N monotherapy.

Improved insulin sensitivity with the angiotensin II-receptor blocker losartan in patients with hypertension and other cardiovascular risk factors.

We aimed to compare the effects of two different vasodilating principles, angiotensin II-receptor blockade and calcium channel blockade, on peripheral insulin-mediated glucose uptake in patients with hypertension and other cardiovascular risk factors. Twenty-one hypertensive patients (11 women and 10 men) with mean age 58.6 years (range 46-75 years), body mass index 29.2 +/- 1.0 kg/m(2) and blood pressure 160 +/- 3/96 +/- 2 mm Hg entered a 4-week run-in period with open-label amlodipine 5 mg. Thereafter they were randomized double-blindly to additional treatment with amlodipine 5 mg or losartan 100 mg. After 8 weeks of treatment, all patients underwent clinical examination and laboratory testing, and 17 of them underwent a hyperinsulinaemic isoglycaemic glucose clamp. After a 4-week open-label wash-out phase, the participants crossed over to the opposite treatment regimen and final examinations with hyperinsulinaemic isoglycaemic glucose clamp after another 8 weeks. Blood pressure was lowered to the same level in both treatment periods. The glucose disposal rate was significantly higher after treatment with losartan 100 mg + amlodipine 5 mg compared to amlodipine 10 mg (4.9 +/- 0.4 vs 4.2 +/- 0.5 mg/kg/min, P = 0.039). Thus our data suggest that angiotensin II-receptor blockade with losartan improves glucose metabolism at the cellular level beyond what can be expected by the vasodilatation and blood pressure reduction alone.

Relationship of the electrocardiographic strain pattern to left ventricular structure and function in hypertensive patients: the LIFE study. Losartan Intervention For End point.

OBJECTIVES: This study was designed to assess the relation of electrocardiographic (ECG) strain to increased left ventricular (LV) mass, independent of its relation to coronary heart disease (CHD). BACKGROUND: The classic ECG strain pattern, ST depression and T-wave inversion, is a marker for left ventricular hypertrophy (LVH) and adverse prognosis. However, the independence of the relation of strain to increased LV mass from its relation to CHD has not been extensively examined. METHODS: Electrocardiograms and echocardiograms were examined at study baseline in 886 hypertensive patients with ECG LVH by Cornell voltage-duration product and/or Sokolow-Lyon voltage enrolled in the Losartan Intervention For End point (LIFE) echocardiographic substudy. Strain was defined as a downsloping convex ST segment with inverted asymmetrical T-wave opposite to the QRS axis in leads V5 and/or V6. RESULTS: Strain occurred in 15% of patients, more commonly in patients with than without evident CHD (29%, 51/175 vs. 11%, 81/711, p < 0.001). When differences in gender, race, diabetes, systolic pressure, serum creatinine and high density lipoprotein cholesterol were controlled, strain on baseline ECG was associated with greater indexed LV mass in patients with (152 +/- 33 vs. 131 +/- 32 g/m2, p < 0.001) or without CHD (131 +/- 24 vs. 119 +/- 22 g/m2, p < 0.001). In logistic regression analyses, strain was associated with an increased risk of anatomic LVH in patients with CHD (relative risk 5.14, 95% confidence interval [CI] 1.16 to 22.85, p = 0.0315), without evident CHD (relative risk 2.91, 95% CI 1.50 to 5.65, p = 0.0016), and in the overall population when CHD was taken into account (relative risk 2.98, 95% CI 1.65 to 5.38, p = 0.0003). CONCLUSIONS: When clinical evidence of CHD is accounted for, ECG strain is likely to indicate the presence of anatomic LVH. Greater LV mass and higher prevalence of LVH in patients with strain offer insights into the known association of the strain pattern with adverse outcomes.

Markers of collagen synthesis is related to blood pressure and vascular hypertrophy: a LIFE substudy.

Cardiac fibrosis and high levels of circulating collagen markers has been associated with left ventricular (LV) hypertrophy. However, the relationship to vascular hypertrophy and blood pressure (BP) load is unclear. In 204 patients with essential hypertension and electrocardiographic LV hypertrophy, we measured sitting BP, serum collagen type I carboxy-terminal telopeptide (ICTP) reflecting degradation, procollagen type I carboxy-terminal propeptide (PICP) reflecting synthesis and LV mass by echocardiography after 2 weeks of placebo treatment and after 1 year of antihypertensive treatment with a losartan- or an atenolol-based regimen. Furthermore, we measured intima-media thickness of the common carotid arteries (IMT), minimal forearm vascular resistance (MFVR) by plethysmography and ambulatory 24-h BP in around half of the patients. At baseline, PICP/ICTP was positively related to IMT (r=0.24, P<0.05), MFVR(men) (r=0.35, P<0.01), 24-h systolic BP (r=0.24, P<0.05) and 24-h diastolic BP (r=0.22, P<0.05), but not to LV mass. After 1 year of treatment with reduction in systolic BP (175+/-15 vs 151+/-17 mmHg, P<0.001) and diastolic BP (99+/-8 vs 88+/-9 mmHg, P<0.001), ICTP was unchanged (3.7+/-1.4 vs 3.8+/-1.4 microg/l, NS) while PICP (121+/-39 vs 102+/-29 microg/l, P<0.001) decreased. The reduction in PICP/ICTP was related to the reduction in sitting diastolic BP (r=0.31, P<0.01) and regression of IMT (r=0.37, P<0.05) in patients receiving atenolol and to reduction in heart rate in patients receiving losartan (r=0.30, P<0.01). In conclusion, collagen markers reflecting net synthesis of type I collagen were positively related to vascular hypertrophy and BP load, suggesting that collagen synthesis in the vascular wall is increased in relation to high haemodynamic load in a reversible manner.

Myocardial potassium uptake and catecholamine release during cardiac sympathetic nerve stimulation.

To determine whether sympathetic nerve stimulation induces a significant potassium uptake in the myocardium, the changes in myocardial potassium balance, catecholamine release, lactate uptake, and oxygen consumption were recorded in eight anaesthetised open chest pigs during electrical stimulation of the right intermediate cardiac nerve at 10 Hz. Potassium concentrations were continuously measured by polyvinylchloride valinomycin minielectrodes in arterial and coronary sinus blood. Potassium concentration in coronary sinus blood fell to a nadir 0.42(0.21-0.61) mmol.litre-1 below control values (median and 95% confidence interval) and resulted in a peak potassium uptake of 65(38-102) mumol.min-1 100 g-1 after 2.5(2.0-3.0) min, which correlated (r = 0.94, p less than 0.001) with cardiac noradrenaline release. Accumulated myocardial potassium uptake amounted to 139(82-241) mumol.100 g-1 when a stable potassium concentration difference between arterial and coronary sinus blood was reached after 5.5(4.25-6.50) min. Cardiac contractility (LV dP/dt), myocardial oxygen consumption, and lactate uptake rose from control to peak potassium uptake (p less than 0.001) by 140%, 158%, and 92% respectively. Coronary sinus blood noradrenaline and adrenaline concentrations rose significantly (p less than 0.01) from 58(44-87) pg.ml-1 at control to 2208(1159-5627) pg.ml-1 at peak uptake and from 15(11-19) pg.ml-1 to 85(64-230) pg.ml-1 respectively. Arterial noradrenaline increased from 29(19-41) pg.ml-1 to 374(176-640) pg.ml-1 and arterial adrenaline rose from 15(11-23) pg.ml-1 to 31(24-52) pg.ml-1 (p less than 0.001). It is concluded that sympathetic nerve stimulation induces a substantial myocardial potassium uptake in a dose dependent relation to cardiac noradrenaline release and alters the contractile and metabolic state of the heart substantially with only minor changes in arterial catecholamine concentration.

Insulin sensitivity is related to physical fitness and exercise blood pressure to structural vascular properties in young men.

Insulin resistance is related to physical inactivity, which is a risk factor for cardiovascular disease and death. Moreover, blood pressure responses during the first 6 minutes of an exercise test (600 kilo/pound/meter [kpm] per min) are more predictive for cardiovascular morbidity and mortality than blood pressure at rest, which could reflect that exercise blood pressure correlates more closely to peripheral structural vascular changes than casual blood pressure. We have recently shown a correlation between insulin resistance and minimal forearm vascular resistance (MFVR) in young men recruited from the highest blood pressure percentiles during a military draft session. In the present study, we tested the hypotheses that insulin sensitivity relates to physical fitness and that blood pressure responses during an exercise test relate to peripheral structural vascular changes in these men; we also tested whether these findings were interrelated. We assessed insulin sensitivity and physical fitness in 27 young men randomly selected from the cohort having a blood pressure of 140/90 mm Hg or higher during the compulsory military draft session in Oslo. Insulin sensitivity correlated with physical fitness (r=0.58, P=0.002). Systolic blood pressure after 6 minutes of exercise (600 kpm/min) correlated with MFVR (r=0.46, P=0.015). MFVR and physical fitness independently explained 60% of the variation in insulin sensitivity, and MFVR independently explained 19% of the variation of systolic blood pressure after 6 minutes of exercise. In conclusion, insulin sensitivity is related to physical fitness and exercise blood pressure to structural vascular properties in these young men.

Effect of angiotensin II receptor blockade on fibrinolysis during acute hyperinsulinemia in patients with essential hypertension.

We performed the present study to investigate indirectly the in vivo effects of angiotensin II on fibrinolysis and catecholamines by treatment with losartan, a selective angiotensin II type 1 receptor antagonist. The effects were evaluated in basal conditions as well as in two different models of acute hyperinsulinemia physiologically induced by oral glucose ingestion and by a euglycemic glucose clamp technique. Twenty subjects with moderate hypertension were included in a randomized, double-blind, placebo-controlled crossover study of 4-week treatment periods. Plasma levels of catecholamines, tissue plasminogen activator activity and antigen, and plasminogen activator inhibitor type 1 activity and antigen were unchanged in the basal state after 4 weeks of treatment. During both models of hyperinsulinemia, plasminogen activator inhibitor activity and antigen decreased significantly (both P<.001), and tissue plasminogen activator activity increased significantly (P<.Ol). Norepinephrine did not change during any of the procedures, whereas epinephrine increased significantly after 3 hours of the oral glucose tolerance test. Changes from baseline did not differ between the treatment and placebo regimens during the hyperinsulinemic procedures with regard to either of the fibrinolytic variables or the catecholamines. In conclusion, we could not demonstrate any effects of 4 weeks of treatment with losartan on plasma levels of fibrinolytic variables or catecholamines either in basal conditions or during acute hyperinsulinemia. However, the present findings do not preclude more direct effects of angiotensin II or involvement of other receptor subtypes on fibrinolysis.

Cardiovascular reactivity, coronary risk factors, and sympathetic activity in young men.

We have previously demonstrated that awareness of high blood pressure may increase blood pressure, plasma catecholamine levels, and stress responses. In the present study, three groups of 19-year-old men, all unaware of their blood pressure status, were selected from the first (group-1, 62 +/- 2 mm Hg, [mean +/- SEM], n = 15), 50th (group-50, 90 +/- 4 mm Hg, n = 15), and 99th (group-99, 123 +/- 5 mm Hg, n = 14) percentiles in causal mean blood pressure at a screening. They were studied (blinded examiners) with intra-arterial blood pressure recordings and multiple measurements of arterial plasma epinephrine and norepinephrine during a mental arithmetic challenge and cold pressor test. Despite high mean blood pressure at the screening, group-99 did not differ from group-50 either in intra-arterial mean blood pressure after 30 minutes of supine rest (89 +/- 3 versus 86 +/- 2 mm Hg) or in serum lipids and resting plasma epinephrine and norepinephrine. However, in group-99 resting plasma epinephrine showed a positive hyperbolic relation to resting diastolic blood pressure (r = .73, P = .004) and a negative hyperbolic relation to the ratio of high-density lipoprotein cholesterol to total cholesterol (r = -.75, P = .002). None of these correlations were present in the two other groups. Furthermore, the three groups differed in heart rate responses (P < .0005) and systolic (P < .0005) and diastolic (P < .05) blood pressure responses to mental arithmetic challenge, group-99 being hyperreactive compared with the other two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of circulating epinephrine on platelet function and hematocrit.

We investigated the effect of raising arterial plasma epinephrine within the lower pathophysiological concentration range on various indicators of blood platelet function and hematocrit. Epinephrine was raised over 60 minutes by a stepwise increasing intravenous infusion in 40 healthy men aged 20 to 40 years. Platelet count increased progressively with increasing arterial epinephrine to a maximal change of 69 +/- 6 x 10(9)/L in EDTA-anticoagulated blood and a maximal change of 42 +/- 6 x 10(9)/L in acid-citrate-dextrose (ACD)-anticoagulated blood, and the weight of circulating platelets increased by 29% (P < .001). Platelet size increased significantly in EDTA and decreased in ACD, and the difference between EDTA and ACD was significant (P < .0001) for both count and size, suggesting that epinephrine not only recruits platelets into the circulation but also induces some microaggregation in vivo or adhesion ex vivo. Aggregation of platelets in vitro induced by epinephrine decreased (P < .003 for delta optical density and P = .038 for maximal optical density) after epinephrine infusion compared with saline but did not change when stimulated with ADP or collagen. These findings suggest a selective downregulation of the epinephrine-activating mechanisms concomitant with a rise in the platelet content of epinephrine by 81% (P < .001) and no change in the platelet sodium-proton membrane exchange. The release of granular content (beta-thromboglobulin and platelet factor 4) to the circulation in response to epinephrine was not significant. Thus, under acute conditions it seems that the platelets may protect themselves against inappropriate overstimulation by epinephrine. The importance of platelet epinephrine uptake is still unknown, but sodium-proton exchange does not seem to be involved in regulating the effects of circulating epinephrine on platelet function. Epinephrine has a pronounced effect on raising hematocrit (maximal change of 1.74 +/- 0.13 x 10(-2), P < .0001).

The glucose clamp procedure activates the sympathetic nervous system even in the absence of hyperinsulinemia.

There is a well established connection between hyperinsulinemia and hypertension, and activation of the sympathetic nervous system (SNS) by insulin has been proposed as one mechanism. In short term infusion studies, hyperinsulinemia during the euglycemic glucose clamp examination is associated with increased norepinephrine concentration. However, many of the studies lack sufficient control groups. The euglycemic glucose clamp examination could possibly, by discomfort from iv cannulas, the use of heating cuffs, and prolonged immobilization, by itself increase SNS activity. To examine this, we included nine controls, who had saline instead of glucose and insulin infused iv, among other healthy young men (n = 50) who underwent the euglycemic hyperinsulinemic glucose clamp. During hyperinsulinemic clamp, the plasma norepinephrine concentration increased from 0.87 +/- 0.06 to 1.06 +/- 0.05 nmol/L; in the control study, it increased from 0.99 +/- 0.14 to 1.21 +/- 0.11 nmol/L, a significant treatment effect (P < 0.001, by repeated measures analysis of variance), but no group x treatment effect (P = 0.17), i.e. there was no difference between the groups. There were no significant changes in systolic or diastolic blood pressure, heart rate, or plasma epinephrine concentration during the clamps, nor any differences between the groups. We conclude that the increase in plasma norepinephrine concentration observed during an euglycemic glucose clamp examination may be attributed to the procedure itself, and that the inclusion of a control group is mandatory when assessing SNS activity.