Plasma adiponectin concentration is associated with ambulatory daytime systolic blood pressure but not with the dipping status

Obesity in Hypertensive Patients Is Characterized by a Dawn Phenomenon in Systolic Blood Pressure Values and Variability

One of the causes of hypertension is excess weight gain, which can also affect the course of this disease. Both the diagnosis and management of hypertension commonly use ambulatory blood pressure monitoring; the results of which correlate more strongly with cardiovascular diseases and cardiovascular death than office blood pressure monitoring. We evaluated blood pressure values and their variability from hour to hour to see if and when they differed between hypertensive patients with and without obesity. The study included 1345 patients who underwent 24 h ambulatory blood pressure monitoring and then were divided into groups according to body mass index and waist circumference. The obtained data were analyzed according to the subjects' wake-up time, and short-term blood pressure variability parameters were calculated as the mean of the absolute values of the differences between consecutive measurements. The systolic blood pressure in obese subjects was significantly higher between 1 and 5 h before waking than in normal-weighted individuals. In turn, the variability in systolic and diastolic blood pressure was higher with increasing body mass index. The difference in systolic blood pressure values and blood pressure variability was most prominent in the last 5 h of sleep in obese patients.

The effect of antenatal factors and postnatal growth on serum adiponectin levels in children

Low levels of serum adiponectin (i.e. hypoadiponectinaemia) are a marker of cardiometabolic risk in overweight children. It is not clear whether early-life factors may play a role in the development of hypoadiponectinaemia. We investigated whether antenatal factors and postnatal growth are associated with childhood adiponectin levels. This was an observational study in a birth cohort (Vulnerable Windows Cohort Study). Anthropometry was measured at birth, at 6 weeks, every 3 months up to 2 years and then every 6 months. Fasting glucose, insulin, lipids and adiponectin were measured at a mean age 11.5 years. Data on 323 children were analysed with age- and sex-adjusted multivariate analyses. The sizes of mother, placenta, fetus and newborn were not significantly associated with adiponectin levels. Current weight, body mass index (BMI), fat mass, waist circumference, glucose, insulin resistance [homeostasis model assessment of insulin resistance (HOMA-IR)], triglycerides and systolic blood pressure were inversely related to adiponectin (P < 0.05). Faster growth in BMI during late infancy and childhood was associated with lower adiponectin levels (P < 0.05). After adjusting for current waist circumference, faster growth in BMI during early infancy was positively associated with adiponectin (P < 0.01). Faster growth in BMI during childhood was inversely associated (P < 0.001). These associations were similar after adjusting for HOMA-IR. We concluded that antenatal factors are not determinants of childhood adiponectin levels. Faster growth in BMI during infancy is associated with higher levels, whereas faster rates during childhood are associated with hypoadiponectinaemia. Hypoadiponectinaemia is a marker of a more adverse cardiometabolic profile in Afro-Caribbean children.

Sympathetic nervous system in obesity-related hypertension: mechanisms and clinical implications

Obesity markedly increases the risk of hypertension and cardiovascular disease, which may be related to activation of the sympathetic nervous system (SNS). Sympathetic overactivity directly and indirectly contributes to blood pressure (BP) elevation in obesity, including stimulation of the renin-angiotensin-aldosterone system (RAAS). The adipocyte-derived peptide leptin suppresses appetite, increases thermogenesis, but also raises SNS activity and BP. Obese individuals exhibit hyperleptinemia but are resistant to its appetite-suppressing actions. Interestingly, animal models of obesity exhibit preserved sympathoexcitatory and pressor actions of leptin, despite resistance to its anorexic and metabolic actions, suggesting selective leptin resistance. Disturbance of intracellular signaling at specific hypothalamic neural networks appears to underlie selective leptin resistance. Delineation of these pathways should lead to novel approaches to treatment. In the meantime, treatment of obesity-hypertension has relied on antihypertensive drugs. Although sympathetic blockade is mechanistically attractive in obesity-hypertension, in practice its effects are disappointing because of adverse metabolic effects and inferior outcomes. On the basis of subgroup analyses of obese patients in large randomized clinical trials, drugs such as diuretics and RAAS blockers appear superior in preventing cardiovascular events in obesity--hypertension. An underused alternative approach to obesity-hypertension is induction of weight loss, which reduces circulating leptin and insulin, partially reverses resistance to these hormones, decreases sympathetic activation and improves BP and other risk factors. Though weight loss induced by lifestyle is often modest and transient, carefully selected pharmacological weight loss therapies can produce substantial and sustained antihypertensive effects additive to lifestyle interventions.