Márk Kollai

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Respiratory sinus arrhythmia (RSA) is frequently employed as an intra- and interindividual index of cardiac parasympathetic tone, although the relationship of RSA to interindividual differences in cardiac vagal tone remains questionable. Our study examined between- and within-subject relations among RSA, cardiac vagal tone, and respiratory parameters.(More)
1. Respiratory modulation of cardiac parasympathetic activity and the relationship between respiratory sinus arrhythmia and parasympathetic control has been studied in twenty-nine conscious, healthy young adult subjects. 2. Changes in heart period in propranolol-treated subjects were taken as the measure of changes in cardiac parasympathetic activity;(More)
Simultaneous recordings were made from vagal and sympathetic fibers innervating the heart in dogs anesthetized with chloralose. Reciprocal relationship between the two autonomic nerves was clearly seen in the baroreceptor reflex. Stimulation of chemoreceptors, however, evoked non-reciprocal responses of the two nerves; at the onset of the chemoreceptor(More)
BACKGROUND Cardiovagal autonomic control declines with age in adult subjects, which is related in part to increasing stiffness of the barosensory vessel wall. It is not known, however, whether autonomic function changes with age in children. METHODS AND RESULTS We studied 137 healthy subjects divided into 4 age groups: group 1, 7 to 14 years; group 2, 11(More)
Exhaled breath condensate (EBC) pH is considered to reflect the acid-base balance of the airways. Current pH measurements do not take into account the effect of CO2. The aim of the present study was to determine the effect of condensate CO2 partial pressure on pH and to provide a more precise mode of EBC pH determination. Condensate pH and CO2 partial(More)
Arterial baroreflex function is altered by dynamic exercise, but it is not clear to what extent baroreflex changes are due to altered transduction of pressure into deformation of the barosensory vessel wall. In this study we measured changes in mean common carotid artery diameter and the pulsatile pressure : diameter ratio (PDR) during and after dynamic(More)
Lung cancer is the leading cause of cancer death. Results of therapeutic interventions are particularly discouraging when the disease is discovered in an advanced stage. Early diagnosis is limited by the fact that the disease usually develops asymptomatically and available screening methods do not fulfil the requirements for reliable discrimination between(More)
The mechanism of control of reciprocal and non-reciprocal action between parasympathetic and sympathetic nerves was investigated. Simultaneous recordings were made from both vagal and sympathetic nerves innervating the heart of responses evoked by hypothalamic stimulation in chloralose-anesthetized dogs. Four patterns of responses could be elicited by(More)
Incidence of orthostatic hypertension is estimated at 5% but is even more prevalent in borderline hypertension and autonomic neuropathies. The aim of this study was to develop a potential model to investigate orthostatic hypertension. We used normotensive and hypertensive Wistar rats to analyze responses and diurnal variations of arterial blood pressure,(More)
Aging is associated with profound changes in the structure and function of the heart. A fundamental understanding of these processes, using relevant animal models, is required for effective prevention and treatment of cardiovascular disease in the elderly. Here, we studied cardiac performance in 4- to 5-mo-old (young) and 24- to 26-mo-old (old) Fischer 344(More)