BACKGROUND: We investigated whether there are subgroups with different underlying (latent) trajectories of midlife systolic blood pressure (BP), diastolic BP, and pulse pressure in a UK cohort. METHODS: Data are from 1840 men and 1819 women with BP measured at ages 36, 43, and 53 years. We used unconditional growth ...

BackgroundCardiovascular disease is common in diabetes, and is associated with activation of the renin-angiotensin system (RAS). Angiotensin-converting enzyme (ACE)2 is a recently described member of the RAS, and this study investigated whether ACE2 polymorphisms are associated with hypertension, left ventricular (LV) mass, and cardiac function in type 2 diabetes.MethodsVariants in ...

OBJECTIVES: Data relating blood pressure (BP) class to subclinical organ damage are infrequently reported in populations with a traditional 'nonwestern' lifestyle. As the relevance of BP stratification to cardiovascular prognosis has not been elucidated in these low-income countries at the second epidemiological transition, we aimed to study the effect of ...

ABSTRACT: This study was achieved to explore the vascular reactivity of angiotensin II and noradrenaline and their relationship with endothelial function in rabbits fed a high fat diet (HFD). Animals were fed either a HFD or regular chow (CD) for 12 weeks. After 12 weeks, the HFD rabbits showed higher ...

Elevated blood pressure (BP) at early or mid pregnancy is a known risk factor for pregnancy-induced hypertension (PIH). However, the association between BP changes during the first half of pregnancy and subsequent PIH development is unknown. We used changes in maternal BP between 16 and 20 weeks of gestation to ...

To investigate the daytime vs nighttime differences in intraocular pressure (IOP), aqueous humor dynamics, central cornea thickness, and blood pressure among a cohort of healthy volunteers. Thirty healthy volunteers (mean [SD] age, 57.0 [8.6] years) were enrolled in the study. Individuals underwent 1 daytime visit and 1 nighttime visit for ...

Abstract Previous research has shown that hypoxia-acclimated Atlantic cod (Gadus morhua) have significantly reduced cardiac function but can consume more oxygen for a given cardiac output (Q). However, it is not known (1) which physiological changes permit a greater "oxygen pulse" (oxygen consumed per mL of blood pumped) in hypoxia-acclimated ...

Maturation arrest (MA) of spermatogenesis is diagnosed on histology as interruption of spermatogenesis before the final stage without impairment of Sertoli or Leydig cells. It is considered a condition of irreversible or absolute infertility. Varicocele, which represents impairment in the testicular venous drainage system, has been shown to be a ...

Abstract Previous studies identified NADPH oxidases (Nox) and mitochondrial electron transport chain at complex I as major cellular sources of reactive oxygen species (ROS) mediating systemic and cellular responses to intermittent hypoxia (IH). In the present study, we investigated potential interactions between Nox and the mitochondrial complex I and assessed ...

Oxidative stress induced by overproduction of reactive oxygen species (ROS) plays an important role in hypoxia/reoxygenation (H/R) injury. In the present study, effects of salvianolic acid A (1) on heart H/R injury through its antioxidant activity were examined, using a molecule-based ROS scavenging system and cardiomyocyte model of H/R injury, ...

The present study investigated whether BAY 41-2272(5-cyclopropyl-2-[1-(2-fluoro-benzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]-pyrimidin-4-ylamine), a novel pyrazolopyridine that activates guanylyl cyclase and sensitizes the enzyme towards nitric oxide (NO), inhibits the development of pulmonary hypertension. BAY 41-2272 (1 or 10 mg/kg/day) was administered intraperitoneally, and sildenafil (25 mg/kg/day), an inhibitor phosphodiesterase type 5, was given in the ...

We evaluated how the increase in lung interstitial pressure correlates with the pulmonary vascular response to chronic hypoxia. In control and hypoxic (30 days; 10% O(2)) Wistar male rats, we measured: pulmonary interstitial pressure (P(ip)), cardiac and haemodynamic parameters by echocardiography, and performed lung morphometry on tissue specimens fixed in ...

Intrapulmonary arteriovenous (IPAV) shunting has been shown to occur at rest in some subjects breathing a hypoxic gas mixture [fraction of inspired oxygen (FI(O(2))) = 0.12] for brief periods of time. In the present study we set out to determine if IPAV shunting could be induced at rest in all ...

The effect of prolonged hypoxemia in early life on systemic arterial blood pressure at maturity was assessed in Sprague-Dawley rats. Animals hypoxic in early life (12 males, 10 females) were raised in hypoxia (FiO₂ = 0.12) for the first 10 days of life and subsequently raised in normoxia, along with ...

Physiological adaptations to intermittent hypoxia (IH) conditioning are based on the cumulative effect of repeated IH exposures. The present study sought to test the hypothesis that acute IH exposures would promote arterial O(2) delivery and regional tissue oxygenation. Changes in arterial O(2) saturation (SaO(2), oximeter), forearm muscle and cerebral tissue ...

Intermittent hypoxia (IH) is believed to contribute to the pathogenesis of hypertension in obstructive sleep apnea through mechanisms that include activation of the renin-angiotensin system. The objective of this study was to assess the role of the type I angiotensin II receptor in mediating an increase in arterial pressure associated ...

With increasing altitude, there is a fall in barometric pressure and a progressive fall in the partial pressure of oxygen. Acclimatization describes the physiologic changes that help maintain tissue oxygen delivery and human performance in the setting of hypobaric hypoxemia. These changes include a marked increase in alveolar ventilation, increased ...

Lung carbon monoxide (CO) transfer and pulmonary capillary blood volume (Vc) at high altitudes have been reported as being higher in native highlanders compared to acclimatised lowlanders but large discrepancies appears between the studies. This finding raises the question of whether hypoxia induces pulmonary angiogenesis. Eighteen highlanders living in Bolivia ...

Under certain conditions, Arthrex AR-6400 and AR-6475 arthroscopic irrigation/distention pumps can create pressures within the patient's joint that are more than twice the desired pressure without alerting the clinician, increasing the potential for serious patient injury due to extracapsular solution infiltration. Facilities need to thoroughly understand the behavior of these ...

Subterranean rodents construct large and complex burrows and spend most of their lives underground, while fossorial species construct simpler burrows and are more active above ground. An important constraint faced by subterranean mammals is the chronic hypoxia and hypercapnia of the burrow atmosphere. The traits, regarded as "adaptations of rodents ...

In one series of experiments, heart frequency (f (H)), blood pressure (P (a)), gill ventilation frequency (f ( R )), ventilation amplitude (V (AMP)) and total gill ventilation (V (TOT)) were measured in intact jeju (Hoplerythrinus unitaeniatus) and jeju with progressive denervation of the branchial branches of cranial nerves IX ...

BACKGROUND: Activation of the endothelin-1 (ET-1) pathway may be involved in hypoxia-induced pulmonary vasoconstriction, increase in pulmonary pressure and high altitude pulmonary oedema. Thus, we investigated the effect of the ETA/ETB receptor antagonist, bosentan, on pulmonary artery systolic pressure (PASP) in healthy subjects (n = 10). DESIGN: We used a ...

Loss of medullary sympathoexcitatory neurons may contribute to baroreflex failure, leading to orthostatic hypotension in multiple-system atrophy (MSA). The cardiovascular responses to chemoreflex activation in MSA have not been explored to date. To determine whether ventilatory and cardiovascular responses to hypercapnia and hypoxia during wakefulness are systematically impaired in MSA. ...

Altered S-nitrosothiols (RSNO) signaling is linked to pulmonary hypertension. Recent studies have shown that S-nitrosoglutathione (GSNO) reductase (GSNOR) catalyzes the degradation of GSNO and indirectly regulates the level of RSNO in vivo. Our present study tested the hypothesis that chronic hypoxia causes pulmonary hypertension, in part, by the change of ...

Tinnitus and dizziness are symptoms of acute mountain sickness. We investigated the mechanism by which high altitude (i.e. hypobaric hypoxia) affects inner ear function by measuring transient evoked otoacoustic emissions (TEOAE) and distortion product otoacoustic emissions (DPOAE) under conditions of normobaric normoxia (1,013 hPa; 760 mm Hg) and hypobaric hypoxia ...

The obstructive sleep apnea (OSA) syndrome, characterized by repeated episodes of intermittent hypoxia is recognized as an independent risk factor for hypertension. One potential contributing mechanism to the OSA-induced hypertension is the potentiation of the carotid body chemosensory responses to hypoxia, which is responsible for the augmented sympathetic modulation of ...

Staged ascent (SA), temporary residence at moderate altitude en route to high altitude, reduces the incidence and severity of noncardiopulmonary altitude illness such as acute mountain sickness. To date, the impact of SA on pulmonary arterial pressure (PAP) is unknown. We tested the hypothesis that SA would attenuate the PAP ...

Intermittent hypoxia, a feature of obstructive sleep apnoea, potentiates ventilatory hypoxic responses, alters heart rate variability and produces hypertension, partially owing to an enhanced carotid body responsiveness to hypoxia. Since oxidative stress is a potential mediator of both chemosensory and cardiorespiratory alterations, we hypothesised that an antioxidant treatment may prevent ...

Clinical studies have shown that fluctuation in the plasma concentrations of estrogen during the menstrual cycle has an effect on myocardial health in premenopausal women. When estrogen levels are low, the number of ischemic events experienced is increased. To determine whether the increased ischemic events reported with low plasma estrogen ...

To compare performance of right- versus left-sided double-lumen tubes (DLTs) among infrequent users by evaluating the incidence and severity of hypoxemia, hypercapnia, and high airway pressures. A retrospective, cohort study. A university hospital. Ninety-eight patients undergoing left-sided DLT placement (53.9 +/- 21.2 years old) and 98 patients undergoing right-sided DLT ...

The role of vascular endothelial growth factor (VEGF) and erythropoietin (EPO) in mediating hypoxic preconditioning under the acute intermittent hypoxic condition (AIH) was investigated in this study. Male Wistar rats were randomly assigned and kept in normoxic conditions, (Nx) or in AIH conditions and subjected to brief cycles hypoxia/reoxygenation. Hearts ...

OBJECTIVES: Previous analyses of physiologic parameter changes during ascent to altitude have incorporated small numbers of well-trained climbers. The effects of altitude illness are more likely to occur and may come to medical attention more frequently in unacclimatized recreational individuals. We sought to evaluate acute changes in physiologic parameters during ...

OBJECTIVES: Involuntary apnea episodes in obstructive sleep apnea patients result in selective potentiation of peripheral chemoreceptor regulation of sympathetic vasomotor tone. Breath-hold diving is associated with repeated "voluntary" apnea episodes and massive arterial oxygen desaturation, which could also perturb chemoreflex function. METHODS: We measured ventilation, heart rate, blood pressure, cardiac ...

CONTEXT: Hypoxia is a major cause of pulmonary hypertension in respiratory disease and at high altitude. Recent work has established that the effect of hypoxia on pulmonary arterial pressure may depend on iron status, possibly acting through the transcription factor hypoxia-inducible factor, but the pathophysiological and clinical importance of this ...

Acclimatization to long-term hypoxia takes place at high altitude and allows gradual improvement of the ability to tolerate the hypoxic environment. An important component of this process is the hypoxic ventilatory acclimatization (HVA) that develops over several days. HVA reveals profound cellular and neurochemical re-organization occurring both in the peripheral ...

Acute respiratory disorders and permissive hypercapnic strategy may lead to alveolar hypoxia and hypercapnic acidosis. However, the effects of hypercapnia with or without acidosis on hypoxic pulmonary vasoconstriction (HPV) and oxygen diffusion capacity of the lung are controversial. We investigated the effects of hypercapnic acidosis and hypercapnia with normal pH ...

Analysis of exhaled nitric oxide (NO) has become an accepted complementary tool in the management of inflammatory airway diseases. Previous studies have demonstrated reduced exhaled NO at altitude and ascribed their findings to hypoxia. We studied exhaled NO partial pressures (Pe(NO)) in eight healthy subjects at reduced ambient pressure down ...

BACKGROUND: We hypothesised that the potential protective effects of endothelial ET(B) are important in limiting pulmonary vascular muscularisation, vasoconstriction and the development of pulmonary arterial hypertension in response to hypoxia. METHODS: EC-specific ET(B) knockout mice (EC ET(B)(-/-)) and control mice (ET(B)(f/f)) were subjected to hypobaric hypoxic (10% FiO2) or normoxic ...

Cerebral venous hypertension (VH) and angiogenesis are implicated in the pathogenesis of brain arteriovenous malformation and dural arteriovenous fistulae. We studied the association of VH and angiogenesis using a mouse brain VH model. Sixty mice underwent external jugular vein and common carotid artery (CCA) anastomosis (VH model), CCA ligation, or ...

Intermittent hypoxia (IH) is thought to be responsible for many of the long-term cardiovascular consequences associated with obstructive sleep apnoea (OSA). Experimental human models of IH can aid in investigating the pathophysiology of these cardiovascular complications. The purpose of this study was to determine the effects of IH on the ...

The function of the cardiovascular system during hypoxia is an important determinant of neurologic outcome. Oscillations in blood pressure, particularly type-3 waves with a duration of 10 to 160 s, have been shown to occur in the presence of hypoxia in the neonatal rat. The aim of this study was ...

Hemoglobin (Hb)-based oxygen carriers (HBOCs) are being developed as a potential therapy for increasing tissue oxygenation, yet they have not reached their full potential because of unwanted hemodynamic side effects (vasoconstriction, low cardiac output, and oxygen delivery) due in part to nitric oxide (NO) scavenging by cell-free Hb. It may ...

Chronic hypoxia during pregnancy has profound effects on uterine artery (UA) contractility and attenuates uterine blood flow. The present study tested the hypothesis that chronic hypoxia inhibits the pregnancy-induced reduction in pressure-dependent myogenic tone of resistance-sized UAs. UAs were isolated from nonpregnant ewes (NPUAs) and near-term pregnant ewes (PUAs) that ...

BACKGROUND AND PURPOSE: The optimal hemoglobin (Hgb) target after aneurysmal subarachnoid hemorrhage is not precisely known. We sought to examine the threshold of Hgb concentration associated with an increased risk of cerebral metabolic dysfunction in patients with poor-grade subarachnoid hemorrhage. METHODS: Twenty consecutive patients with poor-grade subarachnoid hemorrhage who underwent ...

Exposure to cyclic intermittent hypoxia (CIH) is associated with elevated arterial pressure and sustained sympathoexcitation, but the causes of the augmented sympathetic activity remain poorly understood. We recorded arterial pressure, heart rate, and renal sympathetic nerve (RSN) activity in conscious rats previously exposed to either CIH or Sham for 3 ...

OBJECTIVES: The laryngeal chemoreflex is a reflexive central apnea, bradycardia, and cardiovascular collapse that occurs in young, maturing mammals in response to exposure of the laryngeal mucosa to acidic and/or organic stimuli. The severity of the laryngeal chemoreflex varies within a species from one animal to another, and in some ...

Cellular hypoxia is the common final pathway of brain injury that occurs not just after asphyxia, but also when cerebral perfusion is impaired directly (eg, embolic stroke) or indirectly (eg, raised intracranial pressure after head injury). We Review recent advances in the understanding of neurological clinical syndromes that occur on ...

OBJECTIVES: Aspiration has been identified as one of the independent risk factors for development of respiratory tract infections, the incidence of which varies from 10% to 65% in patients in intensive care units. The primary defense mechanism for protection of the lower airway is the glottic closure reflex (GCR), elicited ...

Hypoxia and increased temperature alter venous blood pressures in teleosts through active changes in venous tone. Elasmobranchs possess a capacious venous system but have limited adrenergic vascular innervation and subambient central venous pressure (P(cv)). In this study, we explored venous hemodynamic responses to acute temperature increase and moderate (6.9 kPa) ...

It is unclear whether nitrous oxide (N(2)O) has a protective effect on cardiac function in vitro. In addition, little is known about the cardioprotective effect of anesthesia administered during hypoxia or ischemia. We therefore studied the cardioprotective effects of N(2)O and sevoflurane administered before or during hypoxia in isolated rat ...