Biomaterial Database

Effect of chronic hypoxia on hypoxic ventilatory response in awake rats. 1993

E A Aaron, and F L Powell

Department of Medicine, University of California, San Diego, La Jolla 92093-0623.

We compared the hypoxic ventilatory response (HVR) of two groups of unrestrained awake male rats (300-550 g): those acclimatized to hypoxia > 7 wk at simulated altitude (380 Torr, n = 12) and sea level controls (n = 8). Chronic catheters were placed in the iliac artery and vein 3-7 days before study. An "on-line" system was used to measure arterial PO2 and PCO2. Arterial blood was drawn via a roller pump past O2 and CO2 electrodes and returned to the vein. Batch samples were taken before and after HVR measurements for calibrating and determining arterial pH and hematocrit. Inspired ventilation, tidal volume, and respiratory frequency were measured with barometric pressure plethysmography at several levels of inspired O2 fraction (0.08-0.30) maintained for 15 min. For isocapnic HVR, inspired CO2 fraction was increased as necessary to maintain arterial PCO2 at the hyperoxic level. In both groups, poikilocapnic HVRs (inspired CO2 fraction = 0) were significantly less than isocapnic HVRs. Isocapnic HVRs were significantly greater in hypoxia-acclimatized (2,783 +/- 233 ml.min-1.kg-1) than in sea level control rats (1,826 +/- 106 ml.min-1.kg-1), mainly due to a significant increase in tidal volume (P < 0.05). In conclusion, relieving hypocapnia in hypoxia, by maintaining isocapnia, reveals a significant increase in the ventilatory response to arterial PO2 in awake rats with chronic hypoxia.

UI	MeSH Term	Description	Entries
D008297	Male		Males
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
D002245	Carbon Dioxide	A colorless, odorless gas that can be formed by the body and is necessary for the respiration cycle of plants and animals.	Carbonic Anhydride,Anhydride, Carbonic,Dioxide, Carbon
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
D000064	Acclimatization	Adaptation to a new environment or to a change in the old.	Acclimation
D000531	Altitude	A vertical distance measured from a known level on the surface of a planet or other celestial body.	Altitudes
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D000860	Hypoxia	Sub-optimal OXYGEN levels in the ambient air of living organisms.	Anoxia,Oxygen Deficiency,Anoxemia,Deficiency, Oxygen,Hypoxemia,Deficiencies, Oxygen,Oxygen Deficiencies
D013990	Tidal Volume	The volume of air inspired or expired during each normal, quiet respiratory cycle. Common abbreviations are TV or V with subscript T.	Tidal Volumes,Volume, Tidal,Volumes, Tidal
D015656	Respiratory Mechanics	The physical or mechanical action of the LUNGS; DIAPHRAGM; RIBS; and CHEST WALL during respiration. It includes airflow, lung volume, neural and reflex controls, mechanoreceptors, breathing patterns, etc.	Breathing Mechanics,Breathing Mechanic,Mechanic, Breathing,Mechanic, Respiratory,Mechanics, Breathing,Mechanics, Respiratory,Respiratory Mechanic