Multiparametric magnetic resonance imaging: A robust tool to test pathogenesis and pathophysiology behind nephropathy in humans.

Chronic kidney disease (CKD) is a major population disease. In diabetes as well as hypertension, kidney disease is one of the most serious complications. Recent research has demonstrated that chronic hypoxia is a key actor in the pathogenesis of CKD. In this review, we focus on how functional magnetic resonance imaging (fMRI) techniques can shed light on pathogenetic mechanisms and monitor new treatments aimed at preventing or ameliorating the disease. Multiparametric MRI techniques can measure changes in renal artery flow, tissue perfusion, and oxygenation repetitively over short time periods, enabling high time resolution. Furthermore, renal fibrosis can be quantified noninvasively by MRI diffusion tensor imaging, and techniques are upcoming to measure renal oxygen consumption. These techniques are all radiation and contrast-free. We briefly present data, demonstrating that fMRI techniques can play a major role in future research in CKD, and possibly also in daily clinical practice.

GLP-1 Promotes Cortical and Medullary Perfusion in the Human Kidney and Maintains Renal Oxygenation During NaCl Loading.

Background GLP-1 (glucagon-like peptide-1) receptor agonists exert beneficial long-term effects on cardiovascular and renal outcomes. In humans, the natriuretic effect of GLP-1 depends on GLP-1 receptor interaction, is accompanied by suppression of angiotensin II, and is independent of changes in renal plasma flow. In rodents, angiotensin II constricts vasa recta and lowers medullary perfusion. The current randomized, controlled, crossover study was designed to test the hypothesis that GLP-1 increases renal medullary perfusion in healthy humans. Methods and Results Healthy male participants (n=10, aged 27±4 years) ingested a fixed sodium intake for 4 days and were examined twice during a 1-hour infusion of either GLP-1 (1.5 pmol/kg per minute) or placebo together with infusion of 0.9% NaCl (750 mL/h). Interleaved measurements of renal arterial blood flow, oxygenation (R2*), and perfusion were acquired in the renal cortex and medulla during infusions, using magnetic resonance imaging. GLP-1 infusion increased medullary perfusion (32±7%, P<0.001) and cortical perfusion (13±4%, P<0.001) compared with placebo. Here, NaCl infusion decreased medullary perfusion (-5±2%, P=0.007), whereas cortical perfusion remained unchanged. R2* values increased by 3±2% (P=0.025) in the medulla and 4±1% (P=0.008) in the cortex during placebo, indicative of decreased oxygenation, but remained unchanged during GLP-1. Blood flow in the renal artery was not altered significantly by either intervention. Conclusions GLP-1 increases predominantly medullary but also cortical perfusion in the healthy human kidney and maintains renal oxygenation during NaCl loading. In perspective, suppression of angiotensin II by GLP-1 may account for the increase in regional perfusion. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT04337268.

Capillary transit time heterogeneity inhibits cerebral oxygen metabolism in patients with reduced cerebrovascular reserve capacity from steno-occlusive disease.

The healthy cerebral perfusion demonstrates a homogenous distribution of capillary transit times. A disruption of this homogeneity may inhibit the extraction of oxygen. A high degree of capillary transit time heterogeneity (CTH) describes that some capillaries have very low blood flows, while others have excessively high blood flows and consequently short transit times. Very short transit times could hinder the oxygen extraction due to insufficient time for diffusion of oxygen into the tissue. CTH could be a consequence of cerebral vessel disease. We examined whether patients with cerebral steno-occlusive vessel disease demonstrate high CTH and if elevation of cerebral blood flow (CBF) by administration of acetazolamide (ACZ) increases the cerebral metabolic rate of oxygen (CMRO2), or if some patients demonstrate reduced CMRO2 related to detrimental CTH. Thirty-four patients and thirty-one healthy controls participated. Global CBF and CMRO2 were acquired using phase-contrast MRI. Regional brain maps of CTH were acquired using dynamic contrast-enhanced MRI. Patients with impaired cerebrovascular reserve capacity demonstrated elevated CTH and a significant reduction of CMRO2 after administration of ACZ, which could be related to high CTH. Impaired oxygen extraction from CTH could be a contributing part of the declining brain health observed in patients with cerebral vessel disease.

Renal Artery Stenting in Consecutive High-Risk Patients With Atherosclerotic Renovascular Disease: A Prospective 2-Center Cohort Study.

Background The aim of this study was to prospectively evaluate the effects of renal artery stenting in consecutive patients with severe atherosclerotic renal artery stenosis and high-risk clinical presentations as defined in a national protocol developed in 2015. Methods and Results Since the protocol was initiated, 102 patients have been referred for revascularization according to the following high-risk criteria: severe renal artery stenosis (≥70%) with true resistant hypertension, rapidly declining kidney function, or recurrent heart failure/sudden pulmonary edema. At baseline, the mean 24-hour ambulatory systolic blood pressure was 166.2 mm Hg (95% CI, 162.0-170.4), the defined daily dose of antihypertensive medication was 6.5 (95% CI, 5.8-7.3), and the estimated glomerular filtration rate was 41.1 mL/min per 1.73m2 (95% CI, 36.6-45.6). In 96 patients with available 3-month follow-up data, mean 24-hour ambulatory systolic blood pressure decreased by 19.6 mm Hg (95% CI, 15.4-23.8; P<0.001), the defined daily dose of antihypertensive medication was reduced by 52% (95% CI, 41%-62%; P<0.001), and estimated glomerular filtration rate increased by 7.8 mL/min per 1.73m2 (95% CI, 4.5-11.1; P<0.001). All changes persisted after 24 month follow-up. Among 17 patients with a history of hospitalization for acute decompensated heart failure, 14 patients had no new episodes after successful revascularization. Conclusions In this prospective cohort study, we observed a reduction in blood pressure and antihypertensive medication, an increase in estimated glomerular filtration rate, and a decrease in new hospital admissions attributable to heart failure/sudden pulmonary edema after renal artery stenting. Registration URL: https://clinicaltrials.gov. Identifier: NCT02770066.

Effect of Increased Potassium Intake on Adrenal Cortical and Cardiovascular Responses to Angiotensin II: A Randomized Crossover Study.

Background Increased potassium intake lowers blood pressure in patients with hypertension, but increased potassium intake also elevates plasma concentrations of the blood pressure-raising hormone aldosterone. Besides its well-described renal effects, aldosterone is also believed to have vascular effects, acting through mineralocorticoid receptors present in endothelial and vascular smooth muscle cells, although mineralocorticoid receptors-independent actions are also thought to be involved. Methods and Results To gain further insight into the effect of increased potassium intake and potassium-stimulated hyperaldosteronism on the human cardiovascular system, we conducted a randomized placebo-controlled double-blind crossover study in 25 healthy normotensive men, where 4 weeks treatment with a potassium supplement (90 mmol/day) was compared with 4 weeks on placebo. At the end of each treatment period, we measured potassium and aldosterone in plasma and performed an angiotensin II (AngII) infusion experiment, during which we assessed the aldosterone response in plasma. Hemodynamics were also monitored during the AngII infusion using ECG, impedance cardiography, finger plethysmography (blood pressure-monitoring), and Doppler ultrasound. The study showed that higher potassium intake increased plasma potassium (mean±SD, 4.3±0.2 versus 4.0±0.2 mmol/L; P=0.0002) and aldosterone (median [interquartile range], 440 [336-521] versus 237 [173-386] pmol/L; P<0.0001), and based on a linear mixed model for repeated measurements, increased potassium intake potentiated AngII-stimulated aldosterone secretion (P=0.0020). In contrast, the hemodynamic responses (blood pressure, total peripheral resistance, cardiac output, and renal artery blood flow) to AngII were similar after potassium and placebo. Conclusions Increased potassium intake potentiates AngII-stimulated aldosterone secretion without affecting systemic cardiovascular hemodynamics in healthy normotensive men. Registration EudraCT Number: 2013-004460-66; URL: https://www.ClinicalTrials.gov; Unique identifier: NCT02380157.

Serum B-type natriuretic peptide does not increase with higher systolic blood pressure in obese men despite evidence of blood pressure-related increases in left ventricular mass and filling pressure.

B-type natriuretic peptide (BNP) is a cardiac hormone secreted predominantly from the ventricles in response to increased ventricular pressure. Along this line, hypertensive patients with left ventricular hypertrophy typically have high circulating BNP concentrations. BNP has natriuretic and vasodilatory actions. Obese persons have low circulating BNP concentrations, and a relative lack of this natriuretic and vasodilatory factor could contribute to obesity-related hypertension. The relationship between BNP, BP, left ventricular mass (LVM), and left ventricular filling pressure among obese persons is not clear. To address this issue, we studied 98 healthy obese medication-free men with normal left ventricular ejection fraction. We measured BP using 24 -h ambulatory (A) BP recordings, LVM and E/e', an estimate of left ventricular filling pressure, using echocardiography, and fasting BNP in serum. Mean systolic ABP ± SD was 114 ± 4 mm Hg in 1st and 149 ± 8 mm Hg in 4th systolic ABP quartile, P < 0.001. LVM and E/e' increased across systolic ABP quartiles (mean LVM±SD: 81.5±13.7 g/m2 in 1st and 100.1 ± 26.7 g/m2 in 4th quartile, P = 0.018; mean E/e'±SD: 5.3±1.6 in 1st and 7.0 ± 2.0 in 4th quartile, P = 0.002). In contrast, serum BNP did not increase across systolic ABP quartiles (median (IQR): 6.7 (3.1-12.3) pg/ml in 1st and 5.3 (2.8-9.7) pg/ml in 4th quartile, P = 0.75). Unexpectedly, among healthy obese medication-free men, serum BNP does not increase with higher systolic ABP despite evidence of BP-related increases in LVM and E/e'. This further suggests that a relatively low amount of circulating BNP could contribute to obesity-related hypertension in its early stages.

Effect of increased potassium intake on the renin-angiotensin-aldosterone system and subcutaneous resistance arteries: a randomized crossover study.

BACKGROUND: Increased potassium intake lowers blood pressure (BP) in hypertensive patients. The underlying mechanism is not fully understood but must be complex because increased potassium intake elevates circulating concentrations of the BP-raising hormone aldosterone. METHODS: In a randomized placebo-controlled crossover study in 25 normotensive men, we investigated the effect of 4 weeks of potassium supplement (90 mmol/day) compared with 4 weeks of placebo on the renin-angiotensin-aldosterone system (RAAS), urine composition and 24-h ambulatory BP. Vascular function was also assessed through wire myograph experiments on subcutaneous resistance arteries from gluteal fat biopsies. RESULTS: Higher potassium intake increased urinary potassium excretion (144.7 ± 28.7 versus 67.5 ± 25.5 mmol/24-h; P < 0.0001) and plasma concentrations of potassium (4.3 ± 0.2 versus 4.0 ± 0.2 mmol/L; P = 0.0002), renin {mean 16 [95% confidence interval (CI) 12-23] versus 11 [5-16] mIU/L; P = 0.0047}, angiotensin II [mean 10.0 (95% CI 6.2-13.0) versus 6.1 (4.0-10.0) pmol/L; P = 0.0025] and aldosterone [mean 440 (95% CI 336-521) versus 237 (173-386) pmol/L; P < 0.0001]. Despite RAAS activation, systolic BP (117.6 ± 5.8 versus 118.2 ± 5.2 mmHg; P = 0.48) and diastolic BP (70.8 ± 6.2 versus 70.8 ± 6.3 mmHg; P = 0.97) were unchanged. In the wire myograph experiments, higher potassium intake did not affect endothelial function as assessed by acetylcholine [logarithmically transformed half maximal effective concentration (pEC50): 7.66 ± 0.95 versus 7.59 ± 0.85; P = 0.86] and substance P (pEC50: 8.42 ± 0.77 versus 8.41 ± 0.89; P = 0.97) or vascular smooth muscle cell reactivity as assessed by angiotensin II (pEC50: 9.01 ± 0.86 versus 9.02 ± 0.59; P = 0.93) and sodium nitroprusside (pEC50: 7.85 ± 1.07 versus 8.25 ± 1.32; P = 0.25) but attenuated the vasodilatory response of retigabine (pEC50: 7.47 ± 1.16 versus 8.14 ± 0.90; P = 0.0084), an activator of Kv7 channels. CONCLUSIONS: Four weeks of increased potassium intake activates the RAAS in normotensive men without changing BP and this is not explained by improved vasodilatory responses ex vivo.

A Pilot Study Showing Acute Inhibitory Effect of GLP-1 on the Bone Resorption Marker CTX in Humans.

Bones have been suggested to be a target for glucagon-like peptide -1 (GLP-1); however, studies of the effects on human bones so far have given diverging results. We hypothesized that GLP-1, together with glucagon-like peptide-2 and glucose-dependent insulinotropic polypeptide, plays a role in the gut-bone axis. We examined the acute effect of three GLP-1 receptor ligands [GLP-1 (7-36)amide, GLP-1 (9-36)amide, and exenatide] on markers of bone remodeling. Eight healthy, normal-weight participants, with a mean age of 24.3 years, were studied for 4 days in a double-blinded, randomized clinical trial. Blood was collected before and after s.c. injection of GLP-1 (7-36)amide (1.5 nmol/kg), GLP-1 (9-36)amide (1.5 nmol/kg), exenatide (2.4 nmol/subject), or saline. Plasma was analyzed for bone markers and for osteoprotegerin (OPG), PTH, and IGF-1 levels. All ligands were tested in vitro for their cAMP-inducing activity on the human GLP-1 receptor. GLP-1 (7-36)amide decreased CTX-levels, compared with placebo (area under the curve [AUC] ±SD 0 to 120 min = -2143 ± 1294 % × min versus -883 ± 1557 % × min; p < 0.05). No difference was observed between placebo and GLP-1 (9-36)amide, or between placebo and exenatide, although exenatide had a similar potency as GLP-1 (7-36)amide for cAMP formation in vitro (EC50 of 0.093 and 0.054 nmol/L). However, exenatide reached maximum plasma concentration at 90 min versus 15 min for GLP-1 (7-36)amide, and plasma CTX was significantly decreased during the second hour of the study after exenatide injections compared with placebo (AUC ±SD -463.1 ± 218 % × min and -136 ± 91 % × min; p < 0.05). There was no effect of the injections on bone formation markers (P1NP and osteocalcin) or on OPG, PTH and IGF-1 levels. In conclusion, we show that GLP-1 receptor agonists, but not the primary metabolite GLP-1 (9-36)amide, decrease bone resorption, and suggest that GLP-1 may be part of the gut-bone axis. © 2019 The Authors. JBMR Plus is published by Wiley Periodicals, Inc. on behalf of the American Society for Bone and Mineral Research.

Human renal response to furosemide: Simultaneous oxygenation and perfusion measurements in cortex and medulla.

AIM: Disturbances of renal medullary perfusion and metabolism have been implicated in the pathogenesis of kidney disease and hypertension. Furosemide, a loop diuretic, is widely used to prevent renal medullary hypoxia in acute kidney disease by uncoupling sodium metabolism, but its effects on medullary perfusion in humans are unknown. We performed quantitative imaging of both renal perfusion and oxygenation using Magnetic Resonance Imaging (MRI) before and during furosemide. Based on the literature, we hypothesized that furosemide would increase medullary oxygenation, decrease medullary perfusion, but cause minor changes (<10%) in renal artery flow (RAF). METHODS: Interleaved measurements of RAF, oxygenation (T2 *) and perfusion by arterial spin labelling in the renal cortex and medulla of 9 healthy subjects were acquired before and after an injection of 20 mg furosemide. They were preceded by measurements made during isometric exercise (5 minutes handgrip bouts), which are known to induce changes in renal hemodynamics, that served as a control for the sensitivity of the hemodynamic MRI measurements. Experiments were repeated on a second day to establish that the measurements and the induced changes were reproducible. RESULTS: After furosemide, T2 * values in the medulla increased by 53% (P < 0.01) while RAF and perfusion remained constant. After hand-grip exercise, T2 * values in renal medulla increased by 22% ± 9% despite a drop in medullary perfusion of 7.2% ± 4.7% and a decrease in renal arterial flow of 17.5% ± 1.7% (P < 0.05). Mean coefficients of variation between repeated measurements for all parameters were 7%. CONCLUSION: Furosemide induced the anticipated increase in renal medullary oxygenation, attributable exclusively to a decrease in renal oxygen consumption, since no change of RAF, cortical or medullary perfusion could be demonstrated. All measures and the induced changes were reproducible.

Serum proatrial natriuretic peptide concentrations during oral glucose-induced acute hyperinsulinemia in lean and obese men.

Atrial natriuretic peptide (ANP) is primarily seen as a hormone involved in salt and water homeostasis and blood pressure regulation. Evidence supports a link between metabolism and ANP. Circulating ANP concentrations are low in obese individuals with insulin resistance and hyperinsulinemia. The dynamic relationship between insulin and ANP has been sparsely studied. We therefore measured circulating concentrations of midregional proatrial natriuretic peptide (MR-proANP), a stable marker of ANP secretion, and insulin in lean and obese men during an oral glucose challenge. One hundred and three obese men (body mass index (BMI) ≥30.0 kg/m2) were compared with 27 lean men (BMI = 20.0-24.9 kg/m2). During a 75 g oral glucose challenge, circulating concentrations of MR-proANP and insulin were measured at baseline and every half hour for 2 h. Fasting MR-proANP concentrations were lower in the obese men as compared with the lean men (median (interquartile range): 51.2 (38.7-64.7) pmol/L vs. 69.3 (54.3-82.9) pmol/L, P = 0.002). During the oral glucose challenge, serum MR-proANP concentrations fell steadily in the obese men (P < 0.0001), whereas there was no significant fall in the lean men (P = 0.14). However, the time-course curves of MR-proANP did not display a clear reciprocal relation to the time-course curves of insulin. Adjusted for age, the area under curve (AUC) for MR-proANP was inversely correlated with AUC for insulin (r = -0.38, P < 0.0001). In conclusion, during an oral glucose challenge, serum MR-proANP concentrations drop significantly in obese individuals, but the time-course curves of MR-proANP do not display a reciprocal relationship to the time-course curves of insulin.

Assessment of Perfusion and Oxygenation of the Human Renal Cortex and Medulla by Quantitative MRI during Handgrip Exercise.

BACKGROUND: Renal flow abnormalities are believed to play a central role in the pathogenesis of nephropathy and in primary and secondary hypertension, but are difficult to measure in humans. Handgrip exercise is known to reduce renal arterial flow (RAF) by means of increased renal sympathetic nerve activity. METHODS: To monitor medullary and cortical oxygenation under handgrip exercise-reduced perfusion, we used contrast- and radiation-free magnetic resonance imaging (MRI) to measure regional changes in renal perfusion and blood oxygenation in ten healthy normotensive individuals during handgrip exercise. We used phase-contrast MRI to measure RAF, arterial spin labeling to measure perfusion, and both changes in transverse relaxation time (T2*) and dynamic blood oxygenation level-dependent imaging to measure blood oxygenation. RESULTS: Handgrip exercise induced a significant decrease in RAF. In the renal medulla, this was accompanied by an increase of oxygenation (reflected by an increase in T2*) despite a significant drop in medullary perfusion; the renal cortex showed a significant decrease in both perfusion and oxygenation. We also found a significant correlation (R2=0.8) between resting systolic BP and the decrease in RAF during handgrip exercise. CONCLUSIONS: Renal MRI measurements in response to handgrip exercise were consistent with a sympathetically mediated decrease in RAF. In the renal medulla, oxygenation increased despite a reduction in perfusion, which we interpreted as the result of decreased GFR and a subsequently reduced reabsorptive workload. Our results further indicate that the renal flow response's sensitivity to sympathetic activation is correlated with resting BP, even within a normotensive range.

Obese Hypertensive Men Have Lower Circulating Proatrial Natriuretic Peptide Concentrations Despite Greater Left Atrial Size.

BACKGROUND: Obese persons have lower circulating natriuretic peptide (NP) concentrations. It has been proposed that this natriuretic handicap plays a role in obesity-related hypertension. In contrast, hypertensive patients with left atrial enlargement have higher circulating NP concentrations. On this background, we investigated whether obese hypertensive men could have lower circulating NP concentrations despite evidence of pressure-induced greater left atrial size. METHODS: We examined 98 obese men (body mass index [BMI] ≥ 30.0 kg/m2) and 27 lean normotensive men (BMI 20.0-24.9 kg/m2). All men were healthy, medication free, with normal left ventricular ejection fraction. We measured blood pressure using 24-hour ambulatory blood pressure (ABP) recordings. Hypertension was defined as 24-hour ABP ≥ 130/80 mm Hg, and normotension was defined as 24-hour ABP < 130/80 mm Hg. We determined left atrial size using echocardiography, and we measured fasting serum concentrations of midregional proatrial NP (MR-proANP). RESULTS: Of the 98 obese men, 62 had hypertension and 36 were normotensive. The obese hypertensive men had greater left atrial size (mean ± SD: 28.7 ± 6.0 ml/m2) compared with the lean normotensive men (23.5 ± 4.5 ml/m2) and the obese normotensive men (22.7 ± 5.1 ml/m2), P < 0.01. Nevertheless, despite evidence of pressure-induced greater left atrial size, the obese hypertensive men had lower serum MR-proANP concentrations (median [interquartile range]: 48.5 [37.0-64.7] pmol/l) compared with the lean normotensive men (69.3 [54.3-82.9] pmol/l), P < 0.01, whereas the obese normotensive men had serum MR-proANP concentrations in between the 2 other groups (54.1 [43.6-62.9] pmol/l). CONCLUSIONS: Despite greater left atrial size, obese hypertensive men have lower circulating MR-proANP concentrations compared with lean normotensive men.

Bone Status in Obese, Non-diabetic, Antipsychotic-Treated Patients, and Effects of the Glucagon-Like Peptide-1 Receptor Agonist Exenatide on Bone Turnover Markers and Bone Mineral Density.

Background: Low bone mineral density (BMD) may constitute an underestimated comorbidity in schizophrenia patients undergoing long-term antipsychotic treatment. Glucagon-like peptide 1 (GLP-1) receptor agonists are antidiabetic drugs, which may also affect bone turnover. Methods: In planned secondary analyses of a 3 months, double-blind, randomized, placebo-controlled trial (n = 45), we explored effects of the GLP-1 receptor agonist exenatide 2 mg once-weekly (n = 23), or placebo (n = 22) on bone turnover markers (BTMs) and BMD in chronic, obese, antipsychotic-treated patients with schizophrenia spectrum disorder. Baseline BTMs were compared to sex- and age-adjusted reference values from a Danish population cohort, and T- and Z-scores were calculated for BMD. Results: In women (n = 24), all baseline BTM measurements of procollagen type I N-terminal propeptide (PINP) and C-terminal cross-linking telopeptide of type I collagen (CTX) were within reference values. In men (n = 21), 5% displayed lower PINP and 14% displayed lower CTX. One patient displayed BMD Z-score < -2, and 23% of patients (17% of women and 29% of men) displayed -2.5 < T-scores < -1 indicating osteopenia, but none had osteoporosis. After treatment, PINP decreased at trend level significance (P = 0.05), and body mass index BMD increased for L2-L4 (P = 0.016). No changes in bone markers were significant after correction for mean prolactin levels. Conclusions: Sex- and age-adjusted measures of bone status in chronic, obese, antipsychotic-treated patients appeared comparable to the reference population. Subtle changes in bone markers during 3 months exenatide treatment may suggest beneficial effects of GLP-1 receptor agonists on bone status in antipsychotic-treated patients, and further studies should consider the potential influence of prolactin.

Screening with doppler ultrasound for carotid artery stenosis in patients with stroke or transient ischaemic attack.

INTRODUCTION: Carotid endarterectomy of symptomatic internal carotid artery stenosis in patients with stroke or transient ischaemic attack reduces the risk of recurrent stroke, particularly if performed within 2 weeks from the first event. We evaluated the efficiency of a screening programme based on Doppler ultrasound in patients hospitalized with stroke or transient ischaemic attack in the stroke centre at Rigshospitalet, Glostrup, Denmark, concerning timeliness of referral to the vascular surgeon and performance of carotid endarterectomy according to national recommendations. METHODS: Prospective study of a consecutive cohort of patients with transient ischaemic attack or stroke, referred for carotid Doppler ultrasound over a one-year period. RESULTS: We examined 1390 patients (1048 with stroke, 342 with transient ischaemic attack), 71% within 24 h and 93% within 4 days after admission. Carotid stenosis or occlusion was found in 171 patients (12·3%) and was hemisphere related in 78 patients (5·6%). Among these, 68 (87%) were referred to the vascular department, 94% within 4 days of admission. Carotid endarterectomy was performed in 16 patients, all within 14 days from admission, and was not declined in any patient due to procedural delay. CONCLUSIONS: In a major Danish stroke centre, the national recommended time limit of 4 days in patients with stroke or transient ischaemic attack for screening for carotid stenosis was met in almost all patients. No patients were excluded from surgery as a result of a time limit of 14 days from admission to surgery being exceeded. Of all patients screened, 1·2% underwent carotid endarterectomy.

Epicardial, pericardial and total cardiac fat and cardiovascular disease in type 2 diabetic patients with elevated urinary albumin excretion rate.

Background We evaluated the association of cardiac adipose tissue including epicardial adipose tissue and pericardial adipose tissue with incident cardiovascular disease and mortality, coronary artery calcium, carotid intima media thickness and inflammatory markers. Design A prospective study of 200 patients with type 2 diabetes and elevated urinary albumin excretion rate (UAER). Methods Cardiac adipose tissue was measured from baseline echocardiography. The composite endpoint comprised incident cardiovascular disease and all-cause mortality. Coronary artery calcium, carotid intima media thickness and inflammatory markers were measured at baseline. Cardiac adipose tissue was investigated as continuous and binary variable. Analyses were performed unadjusted (model 1), and adjusted for age, sex (model 2), body mass index, low-density lipoprotein cholesterol, smoking, glycated haemoglobin, and systolic blood pressure (model 3). Results Patients were followed-up after 6.1 years for non-fatal cardiovascular disease ( n = 29) or mortality ( n = 23). Cardiac adipose tissue ( p = 0.049) and epicardial adipose tissue ( p = 0.029) were associated with cardiovascular disease and mortality in model 1. When split by the median, patients with high cardiac adipose tissue had a higher risk of cardiovascular disease and mortality than patients with low cardiac adipose tissue in unadjusted (hazard ratio 1.9, confidence interval: 1.1; 3.4, p = 0.027) and adjusted (hazard ratio 2.0, confidence interval: 1.1; 3.7, p = 0.017) models. Cardiac adipose tissue ( p = 0.033) was associated with baseline coronary artery calcium (model 1) and interleukin-8 (models 1-3, all p < 0.039). Conclusions In type 2 diabetes patients without coronary artery disease, high cardiac adipose tissue levels were associated with increased risk of incident cardiovascular disease or all-cause mortality even after accounting for traditional cardiovascular disease risk factors. High cardiac adipose tissue amounts were associated with subclinical atherosclerosis (coronary artery calcium) and with the pro-atherogenic inflammatory marker interleukin-8.

Acute effects of glucagon-like peptide-1, GLP-19-36 amide, and exenatide on mesenteric blood flow, cardiovascular parameters, and biomarkers in healthy volunteers.

Glucagon-like peptide-1 (GLP-1, GLP-17-36amide) and its sister peptide glucagon-like peptide 2 (GLP-2) influence numerous intestinal functions and GLP-2 greatly increases intestinal blood flow. We hypothesized that GLP-1 also stimulates intestinal blood flow and that this would impact on the overall digestive and cardiovascular effects of the hormone. To investigate the influence of GLP-1 receptor agonism on mesenteric and renal blood flow and cardiovascular parameters, we carried out a double-blinded randomized clinical trial. A total of eight healthy volunteers received high physiological subcutaneous injections of GLP-1, GLP-19-36 amide (bioactive metabolite), exenatide (stable GLP-1 agonist), or saline on four separate days. Blood flow in mesenteric, celiac, and renal arteries was measured by Doppler ultrasound. Blood pressure, heart rate, cardiac output, and stroke volume were measured continuously using an integrated system. Plasma was analyzed for glucose, GLP-1 (intact and total), exenatide and Pancreatic polypeptide (PP), and serum for insulin and C-peptide. Neither GLP-1, GLP-19-36 amide, exenatide nor saline elicited any changes in blood flow parameters in the mesenteric or renal arteries. GLP-1 significantly increased heart rate (two-way ANOVA, injection [P = 0.0162], time [P = 0.0038], and injection × time [P = 0.082]; Tukey post hoc GLP-1 vs. saline and GLP-19-36amide [P < 0.011]), and tended to increase cardiac output and decrease stroke volume compared to GLP-19-36 amide and saline. Blood pressures were not affected. As expected, glucose levels fell and insulin secretion increased after infusion of both GLP-1 and exenatide.

Serum proatrial natriuretic peptide does not increase with higher systolic blood pressure in obese men.

OBJECTIVE: Obese persons have low circulating natriuretic peptide (NP) concentrations. It has been proposed that this 'natriuretic handicap' could play a role in obesity-related hypertension. The normal physiological response of the NP system to an increase in blood pressure (BP) is an increase in NP secretion with concomitant higher circulating NP concentrations. In this study, we investigated whether higher BP would also be related to higher circulating NP concentrations in obese men; furthermore, we verified that BP had affected the hearts of our study participants, by determining left ventricular mass (LVM). METHODS: We examined 103 obese healthy medication-free men. We measured 24-hour ambulatory BP (ABP). LVM was calculated using the Cornell voltage-duration product method. Fasting serum concentrations of midregional proatrial NP (MR-proANP), a surrogate for active ANP, were measured. Linear regression analysis was used to calculate age-adjusted standardised regression coefficients (ß). RESULTS: LVM and BP increased across systolic ABP quartiles (mean LVM±SD: 1599.1±387.2 mm ms in first vs 2188.5±551.3 mm ms in fourth quartile, p<0.001; mean systolic ABP±SD: 114.5±4.2 mm Hg in first vs 149.0±7.7 mm Hg in fourth quartile, p<0.001). Systolic ABP was robustly associated with LVM (ß=0.48, p<0.001). Despite evidence of BP-related increases in LVM, serum MR-proANP was negatively associated with systolic ABP (ß=-0.32, p=0.004) and with diastolic ABP (ß=-0.45, p<0.001). CONCLUSIONS: Contrary to known physiological BP responses, MR-proANP was negatively associated with ABP in our study. This suggests that a low amount of circulating NPs could play a role in the early stage of obesity-related hypertension.