Hypertension
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Questions remain as to whether pediatric sleep disordered breathing increases the risk for elevated blood pressure and blood pressure-dependent cardiac remodeling. We tested the hypothesis that activity-adjusted morning blood pressure surge, blood pressure load, and diurnal and nocturnal blood pressure are significantly higher in children with sleep disordered breathing than in healthy controls and that these blood pressure parameters relate to left ventricular remodeling. 24-hour ambulatory blood pressure parameters were compared between groups. The associations between blood pressure and left ventricular relative wall thickness and mass were measured. 140 children met the inclusion criteria. ⋯ Diurnal and nocturnal systolic blood pressure, diastolic blood pressure, and mean arterial blood pressure predicted the changes in left ventricular relative wall thickness. Therefore, sleep disordered breathing in children who are otherwise healthy is independently associated with an increase in morning blood pressure surge, blood pressure load, and 24-hour ambulatory blood pressure. The association between left ventricular remodeling and 24-hour blood pressure highlights the role of sleep disordered breathing in increasing cardiovascular morbidity.
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Angiotensin II type-1 receptor blockers are widely used with the expectation of prevention of stroke, potential effects to ameliorate of type-2 diabetes, which seems to be closely associated with the impairment of cognitive function in humans. Recently, we have reported that an angiotensin II type-1 receptor blocker prevented cognitive impairment in mice after focal cerebral ischemia, at least partly through an angiotensin II type-2 receptor-mediated increase in a neuroprotective factor, methyl methanesulfonate sensitive-2. Here, we examined the possibility that an angiotensin II type-1 receptor blocker could improve cognitive function in a type-2 diabetic mouse model, KK-A(y). ⋯ Treatment with candesartan markedly increased mRNA expression of angiotensin II type-2 receptor and methyl methanesulfonate sensitive-2 in the brain in KK-A(y) mice, determined by quantitative RT-PCR. In KK-A(y) mice treated with candesartan, age-dependent increases in blood glucose and insulin were significantly suppressed. Our results suggest that candesartan ameliorates the impaired cognitive function in type-2 diabetes mice, at least because of an increased expression of methyl methanesulfonate sensitive-2, a neuroprotective factor, in addition to improvement of glucose intolerance.
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Increased production of organic acid can result in an elevated serum anion gap and may play a role in the development of hypertension. We studied the cross-sectional associations between anion gap and blood pressure and between serum bicarbonate and blood pressure in the 1999-2000 and 2001-2002 National Health and Nutrition Examination Surveys. We included 5043 adult participants who were not taking antihypertensive medications or diuretics and who denied hypertension, cardiovascular disease, diabetes, and other diseases. ⋯ The results were unchanged after excluding participants with estimated glomerular filtration rate <60 cc/min per 1.73 m(2). The anion gap is independently associated with higher blood pressure. Further research is needed to elucidate the relation between organic acid and hypertension.
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Review Meta Analysis
Effect of nocturnal nasal continuous positive airway pressure on blood pressure in obstructive sleep apnea.
Obstructive sleep apnea (OSA) is a very common risk factor for hypertension, and continuous positive airway pressure (CPAP) has been widely used to treat OSA. We conducted a meta-analysis of randomized, controlled trials to evaluate the effects of CPAP on blood pressure, reported as either a primary or secondary end point, among patients with OSA. Studies were retrieved by searching Medline (January 1980 to July 2006), the Cochrane Database of Systematic Reviews, conference abstracts, and bibliographies of review and original articles. ⋯ Mean net change in systolic blood pressure for those treated with CPAP compared with control was -2.46 mm Hg (95% CI: -4.31 to -0.62); mean net change in diastolic blood pressure was -1.83 mm Hg (95% CI: -3.05 to -0.61); and mean net change in mean arterial pressure was -2.22 mm Hg (95% CI: -4.38 to -0.05). Net reductions in blood pressure were not statistically different between daytime and nighttime. These results indicate that CPAP decreases blood pressure among those with OSA and may help prevent hypertension.
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Opioids evoke respiratory depression, bradycardia, and reduced respiratory sinus arrhythmia, whereas serotonin (5-HT) agonists stimulate respiration and cardiorespiratory interactions. This study tested whether serotonin agonists can prevent the inhibitory effects of opioids on cardiorespiratory function. Spontaneous and rhythmic inspiratory-related activity and gamma-aminobutyric acid (GABA) neurotransmission to premotor parasympathetic cardioinhibitory neurons in the nucleus ambiguus were recorded simultaneously in an in vitro thick slice preparation. ⋯ In contrast, BIMU-8 did not alter GABAergic neurotransmission to cardiac vagal neurons by itself but prevented the fentanyl depression of both spontaneous and inspiratory-elicited GABAergic neurotransmission to cardiac vagal neurons. In the presence of tetrodotoxin, the inhibition of GABAergic inhibitory postsynaptic currents with fentanyl is prevented by coapplication of BIMU-8, indicating that BIMU-8 acts at presynaptic GABAergic terminals to prevent fentanyl-induced depression. These results suggest that activation of 5-hydroxytryptamine receptors, particularly 5-hydroxytryptamine 4alpha agonists, may be a useful therapeutic approach in preventing opioid-evoked cardiorespiratory depression.