Ventilatory response to oscillating and non-oscillatingPa
CO
2 in the anesthetized cat |
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Authors: | Axel Fenner Jörg Berndt |
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Institution: | (1) Institut für Physiologie der Ruhr-Universität, Bochum;(2) Kinderklinik der Medizinischen Akademie, Kronsforder Allee 71-73, D-2400 Lübeck |
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Abstract: | Summary In 11 adult cats, lightly anesthetized with chloralose-urethane, blood from both common carotid arteries was led into a plastic chamber of 15–20 ml and returned to the carotids at a point 1.5 cm more cranial. By doing so arterial blood was assumed to pool within the chamber and lose itsP
CO
2 oscillations which are normally known to exist as a result of the respiratory cycle. In control periods blood bypassed the chamber, thus maintaining respiratoryP
CO
2 oscillations. Spontaneous ventilation was measured spirometrically. The animals were breathing pure O2.Results. 1. When the sinus (carotid) nerves were intact or sectioned there was no significant difference in ventilation before or after switching from non-oscillating to oscillatingPa
CO
2. 2. When the vertebral arteries were ligated a drop in ventilation occurred after turning to oscillatingPa
CO
2 which was followed by a slight rise above control values after 30–50 sec. This phenomenon was independent of sinus nerve integrity. Thus in hyperoxie condition the smallPa
CO
2 oscillations known to occur in phase with respiration do not seem to provide a respiratory stimulus to resting ventilation above that generated by the mean level ofPa
CO
2. The ventilatory depression after vertebral artery ligation must at this time remain unexplained. |
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Keywords: | Pa
CO
2 Oscillations Arterial Chemoreceptors Control of Breathing |
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