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Biomedical subjects

J T Reeves

Publications and source records attributed to J T Reeves.

At least 235 records · Page 13Linked to original sources
PubMed1972

Failure of hypoxic pulmonary vasoconstriction in patients with liver cirrhosis.

The combination of arterial hypoxemia and low pulmonary vascular resistance in patients with liver cirrhosis is unexplained. Pulmonary microcirculatory dilation, but not gross arterio-venous shunts, has been the usual postmortem finding in patients with liver cirrhosis. When 10 patients with alcoholic liver cirrhosis breathed 10% oxygen in nitrogen, they failed to increase their pulmonary vascular resistance. However, four patients with functional murmurs, three patients with hyperkinetic heart syndrome, six patients with normal pulmonary artery pressures and intracardiac left to right shunts, and five patients with renal failure and anemia all increased their pulmonary vascular resistances when they breathed 10% oxygen in nitrogen. These findings suggested that in liver cirrhosis the normal regulating mechanism (hypoxic vasoconstriction) of the pulmonary circulation may be impaired, resulting in failure of the lung to match perfusion with ventilation.

Adolescent↗
PubMed1969

Hypoxaemia and aortic chemoreceptor function in foetal lambs.

1. In foetal lambs the effect of raising and lowering arterial P(O2) (by varying the O(2) content of the maternal inspired gas mixture) was studied in order to determine whether the systemic arterial chemoreceptors regulated the circulation.2. From 0.7 of term relative hypoxaemia (e.g. reducing carotid P(O2) from 40 to 20 mm Hg) caused a rise of arterial pressure and femoral vaso-constriction. These changes were unaffected or even increased by bilateral section of the nerves from the carotid sinus and body. They were abolished by section of the vagi or aortic nerves.3. It is concluded that in foetal lambs during the last third of gestation the circulation is under reflex control by the aortic chemoreceptors.

Animals↗
PubMed1969

Cyanide stimulation of the systemic arterial chemoreceptors in foetal lambs.

1. In foetal lambs, delivered by Caesarean section under light chloralose anaesthesia, injection of sodium cyanide into the left atrium or ascending aorta caused a rise of arterial pressure and femoral vasoconstriction. The response to 0.77 mg/kg was barely present at 0.6 of term; by 0.8 of term there was a large response to one third of this dose.2. The cardiovascular response to cyanide injection into the left atrium or ascending aorta was diminished either by section of the vagi or by carotid denervation, and was abolished by cutting both sets of nerves.3. Injection of sodium cyanide into both common carotids simultaneously caused a substantial cardiovascular response and often a respiratory effort, abolished by carotid denervation, whereas injection into a single carotid rarely caused an effect.4. It is concluded that the carotid chemoreceptors in mature foetal lambs can be excited by a stimulus of sufficient intensity, even though they do not respond to moderate hypoxaemia.

Animals↗
PubMed1969

Hypoxia and pulmonary arterial pressure in the rabbit.

1. The effect of hypoxia on pulmonary arterial pressure was studied in young and adult rabbits.2. In isolated perfused lungs, hypoxia caused no rise in pulmonary arterial pressure in rabbits on the day of birth. The size of the hypoxic response increased progressively until 9-11 days of age, when the adult response of a 20% rise of pulmonary arterial pressure at constant flow was attained.3. The intact adult rabbit responded to hypoxia with a 14-30% rise in pulmonary arterial pressure, attributed to vasoconstriction and independent of frequency or tidal volume during positive pressure ventilation.

Age Factors↗