Acta physiologica Polonica
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Hypoxia produced by intravenous infusion of gaseous carbon dioxide was associated in conscious rabbits with decreases in cardiac output and stroke volume. At the same time the arterial blood pressure, oxygen uptake and blood pH decreased, whereas carbon dioxide pressure and lactate level in the arterial blood increased. Pulmonary ventilation increased too, due to the rise in the respiratory frequency and tidal volume. The fall in cardiac output and stroke volume explains a great fall of oxygen uptake in response to decrease of oxygen pressure in the blood.
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The reversibility of osmotic opening of the blood-brain barrier was studied in dogs one hour after intracarotid 3 M urea injection. At that time the permeability of cerebral blood vessels to albumin is restored as evidenced by lack of Evans blue extravasation. Despite that, the response of the urea-perfused hemisphere to changes of perfusion pressure was abnormal. Blood flow in that hemisphere followed passively blood pressure changes in contrast to the contralateral hemisphere in which the blood flow remained independent of the perfusion pressure.
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The construction of a pressure transducer for acute experiments is described. The transducer is intended for direct recording of arterial and venous blood pressure in animals. The characteristics of arterial and venous blood pressure records obtained with a mercury manometer by the classic method and with the transducer are compared.