REGULATION OF BREATHING by changes in arterial blood gases has been the focus of interest for several decades. Although much is known about how changes in arterial blood oxygen levels influence breathing, little is known about whether tissue oxygen levels also affect breathing. Stimulation of breathing during exercise was thought to be mediated by tissue oxygenation that is sensed by chemorecep...

conclusions: the effects of propofol on hemodynamics and arterial oxygen pressure during one- or two-lung ventilation were not different from those of isoflurane. results: sixty patients (mean age = 4124.18 ± 18.63 years) were divided into two groups. the age and gender of the subjects were not statistically different between the two groups. in the propofol group, the arterial oxygen pressure d...

An unsolved issue for the arterial chemoreceptors is the mechanism by which hypoxia and other natural stimuli lead to an increase of activity in the carotid sinus nerve. According to the 'metabolic hypothesis', the hypoxic activation of the carotid body (CB) is mediated by a decrease of the ATP levels in the type I cells, which then release a neurotransmitter capable of exciting the sensory ner...

1. In both the turtle, Pseudemys scripta, and the tortoise, Testudo graeca, lung ventilation is closely accompanied by a tachycardia of predictable magnitude and duration. 2. Efferent vagal activity progressively decreases as heart rate increases with the onset of lung ventilation. Atropine decreases heart rate during apnoea to those levels observed during prolonged breathing series when the de...

Single nerve fiber discharge was recorded from O2 sensitive receptors in the first gill arch of the yellowfin tuna, Thunnus albacares, in vitro. These receptors were innervated by the vagus nerve and increased their discharge in response to decreasing perfusion rate, decreasing perfusion PO2 and, in most fibers, to decreasing external PO2. Fibers responding to environmental hypoxia exhibited an...

Sea anemones capture prey by discharging nematocysts into them. Chemical and mechanical cues identify suitable prey to sensory receptor systems on the anemone. Conjugated N-acetylated sugars from prey bind to chemoreceptors on cnidocyte/supporting cell complexes to tune hair bundles on the complexes to lower frequencies matching prey movements. The hair bundles regulate discharge of microbasic ...

Ligation of one common carotid artery and exposure to carbon monoxide has proved to be a reliable method of producing unilateral cerebral infarcts in the rat, allowing controlled experiments in any given sample size. Pathophysiological measurements in awake and narcotized rats has shown that, in contrast to hypoxic hypoxia, the carbon monoxide-induced functional anaemia (3000 ppm in room air) d...

Breath holding time is the time taken by the subject to hold his breath as long as he can. During voluntary breath holding, tissues continue to utilize oxygen and liberate carbon dioxide. Therefore during breath holding arterial pO2 falls and pCO2 rises. Since both these factors are powerful respiratory stimulants, a point is reached where the respiratory drive becomes so strong that the person...

Oxygen-sensing chemoreceptors contribute significantly to the regulation of the respiratory drive and arterial PO2 levels. The hypoxic ventilatory response (HVR) decreases strongly with age and is modulated by prolonged hypoxia and physical exercise. Several earlier studies indicated that the regulation of the ventilatory response and erythropoietin (EPO) production by the respective oxygen sen...

Oxygen-sensing chemoreceptors contribute significantly to the regulation of the respiratory drive and arterial PO(2) levels. The hypoxic ventilatory response (HVR) decreases strongly with age and is modulated by prolonged hypoxia and physical exercise. Several earlier studies indicated that the regulation of the ventilatory response and erythropoietin (EPO) production by the respective oxygen s...