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BACKGROUND Spectral analysis of RR interval and systolic arterial pressure variabilities may provide indirect markers of the balance between sympathetic and vagal cardiovascular control. METHODS AND RESULTS We examined the relationship between power spectral measurements of variabilities in RR interval, systolic arterial pressure, and muscle sympathetic(More)
BACKGROUND The early hours of the morning after awakening are associated with an increased frequency of events such as myocardial infarction and ischemic stroke. The triggering mechanisms for these events are not clear. We investigated whether autonomic changes occurring during sleep, particularly rapid-eye-movement (REM) sleep, contribute to the initiation(More)
Blood pressure, heart rate, sympathetic nerve activity, and polysomnography were recorded during wakefulness and sleep in 10 patients with obstructive sleep apnea. Measurements were also obtained after treatment with continuous positive airway pressure (CPAP) in four patients. Awake sympathetic activity was also measured in 10 age- and sex-matched control(More)
We assessed the relative roles of aortic (ABR), carotid sinus (CBR), and vagal cardiopulmonary baroreceptors in the reflex control of heart rate and vascular resistance during changes in arterial blood pressure. Injections of phenylephrine (PE) and nitroglycerin (NG) were given intravenously to anesthetized rabbits (chloralose-urethane). Reflex, heart rate(More)
The purpose of these studies was to determine the effects of L-arginine-derived nitric oxide (NO) synthesis on neuronal activity in solitary tract nucleus (NTS) neurons. Single unit activity was recorded extracellularly from medial NTS neurons in Fischer-344 rats in vivo and in vitro. In anesthetized rats with arterial pressure maintained constant,(More)
We compared the effects of isocapnic hypoxia (IHO) and hyperoxic hypercapnia (HC) on sympathetic nerve activity (SNA) recorded from a peroneal nerve in 13 normal subjects. HC caused greater increases in blood pressure (BP), minute ventilation (VE), and SNA [53 +/- 14% (SE) during HC vs. 21 +/- 7% during IHO; P less than 0.05]. Even at equivalent levels of(More)
1. This study evaluated the contribution of carotid and cardiopulmonary baroreceptors to reflex splanchnic and forearm vascular adjustments during venous pooling in man. We compared (a) responses to lower body suction which produces venous pooling with (b) responses to lower body suction plus simultaneous application of neck suction. The rationale was that(More)
Animal studies have demonstrated that activation of the baroreflex by increases in arterial pressure inhibits cardiovascular and ventilatory responses to activation of peripheral chemoreceptors (PC) with hypoxia. In this study, we examined the influences of baroreflex activation on the sympathetic response to stimulation of PC and central chemoreceptors in(More)
Previous studies have demonstrated a significant pressure gradient from carotid artery to pial or middle cerebral arteries. This pressure gradient suggests that large cerebral arteries contribute to cerebral resistance. We have tested the hypothesis that large cerebral arteries contribute to regulation of cerebral blood flow during changes in blood gases(More)