Biomaterial Database

Modulation of human sinus node function by systemic hypoxia. 1982

D L Eckberg, and H Bastow, and A E Scruby

We studied sinus node responses to mild to moderate systemic hypoxia provoked by nitrogen inhalation in five healthy young men. Volunteers maintained their usual tidal volumes and respiratory frequencies at constant levels. We modified carotid arterial baroreceptor activity by applying neck suction or pressure during held expiration. Arterial oxygen saturation began to decline between 8.0 and 9.6 s after the onset of the first breath of nitrogen. Pulse interval declined in parallel with oxygen saturation. During mild hypoxia cardioacceleration was restricted primarily to the inspiratory phase of respiration. Moderate hypoxia diminished the magnitude of sinus arrhythmia. It did not alter baroreflex responsiveness. Our results suggest that in normal humans, augmentation of chemoreceptor input leads to reduction of cardiac vagal motoneuron output. This effect exhibits a distinct respiratory periodicity (more prominent in inspiration) and appears to be independent of any influence of hypoxia on ventilation or baroreflex responsiveness.

UI	MeSH Term	Description	Entries
D008297	Male		Males
D009584	Nitrogen	An element with the atomic symbol N, atomic number 7, and atomic weight [14.00643; 14.00728]. Nitrogen exists as a diatomic gas and makes up about 78% of the earth's atmosphere by volume. It is a constituent of proteins and nucleic acids and found in all living cells.
D010100	Oxygen	An element with atomic symbol O, atomic number 8, and atomic weight [15.99903; 15.99977]. It is the most abundant element on earth and essential for respiration.	Dioxygen,Oxygen-16,Oxygen 16
D011311	Pressoreceptors	Receptors in the vascular system, particularly the aorta and carotid sinus, which are sensitive to stretch of the vessel walls.	Baroreceptors,Receptors, Stretch, Arterial,Receptors, Stretch, Vascular,Stretch Receptors, Arterial,Stretch Receptors, Vascular,Arterial Stretch Receptor,Arterial Stretch Receptors,Baroreceptor,Pressoreceptor,Receptor, Arterial Stretch,Receptor, Vascular Stretch,Receptors, Arterial Stretch,Receptors, Vascular Stretch,Stretch Receptor, Arterial,Stretch Receptor, Vascular,Vascular Stretch Receptor,Vascular Stretch Receptors
D012018	Reflex	An involuntary movement or exercise of function in a part, excited in response to a stimulus applied to the periphery and transmitted to the brain or spinal cord.
D012119	Respiration	The act of breathing with the LUNGS, consisting of INHALATION, or the taking into the lungs of the ambient air, and of EXHALATION, or the expelling of the modified air which contains more CARBON DIOXIDE than the air taken in (Blakiston's Gould Medical Dictionary, 4th ed.). This does not include tissue respiration (	Breathing
D002628	Chemoreceptor Cells	Cells specialized to detect chemical substances and relay that information centrally in the nervous system. Chemoreceptor cells may monitor external stimuli, as in TASTE and OLFACTION, or internal stimuli, such as the concentrations of OXYGEN and CARBON DIOXIDE in the blood.	Chemoreceptive Cells,Cell, Chemoreceptive,Cell, Chemoreceptor,Cells, Chemoreceptive,Cells, Chemoreceptor,Chemoreceptive Cell,Chemoreceptor Cell
D006339	Heart Rate	The number of times the HEART VENTRICLES contract per unit of time, usually per minute.	Cardiac Rate,Chronotropism, Cardiac,Heart Rate Control,Heartbeat,Pulse Rate,Cardiac Chronotropy,Cardiac Chronotropism,Cardiac Rates,Chronotropy, Cardiac,Control, Heart Rate,Heart Rates,Heartbeats,Pulse Rates,Rate Control, Heart,Rate, Cardiac,Rate, Heart,Rate, Pulse
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000328	Adult	A person having attained full growth or maturity. Adults are of 19 through 44 years of age. For a person between 19 and 24 years of age, YOUNG ADULT is available.	Adults