Effect of microcirculation changes on brain tissue oxygenation

Bicher, Haim I.; Bruley, Duane F.; Knisely, Melvin H.; Reneau, Daniel D.

doi:10.1113/jphysiol.1971.sp009594

Cited by 35 publications

(6 citation statements)

References 18 publications

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“…It is not possible to determine from the evidence available how far this reflects a raised cerebral blood flow, a diminished cerebral oxygen consumption, or some varying combination of the two. A similar overshoot of brain tissue Po, following cessation of nitrogen administration has been observed in the cat (Bicher, Brimley, Knisely & Reneau, 1971).…”

Section: Discussionsupporting

confidence: 73%

Cerebral blood flow and oxidative metabolism during hypoxia and asphyxia in the new‐born calf and lamb.

Gardiner¹

1980

The Journal of Physiology

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SUMMARY1. The effects of hypoxia and asphyxia on cerebral blood flow and oxidative metabolism have been investigated in the calf and lamb under sodium pentobarbitone anaesthesia.2. Cerebral blood flow was determined using a hydrogen clearance technique, and cerebral metabolism quantified by the simultaneous measurement of arteriocerebral venous concentration differences for oxygen, glucose and lactate.Continuous measurements were made of arterial and cerebral venous PO, in vivo.3. Both cerebral blood flow and oxygen consumption were less in animals anaesthetized with sodium pentobarbitone than in conscious animals.4. In the calf, recovery from transient episodes of severe hypoxia and asphyxia was associated with a rapid recovery and overshoot of cerebral venous Po2. Evidence was obtained that rapid changes in blood pressure during severe asphyxia were associated with pressure-passive cerebral blood flow. Prolonged hypoxia (Pa, Ad: 21 + 2 mmHg) with normocapnia was associated with an increase in cerebral blood flow, fall in cerebral oxygen consumption, and no change in the glucose-oxygen index.5. In the lamb, prolonged asphyxia (PO: 30+ 1 mmHg; P c02o 56+ 2 mmHg) was associated with an increase in cerebral blood flow. Cerebral glucose uptake did not change, but cerebral oxygen consumption was markedly depressed, and the glucose-oxygen index increased. 6. In the lamb during normoxia, there was a linear correlation between cerebral blood flow and arterial PC0o in the range 10-95 mmHg (r = 0-92; P < 0.001), with a slope of 1'74 ml. 100g-1 min'. mmHg PacoX2' Hypoxia did not significantly increase the fall in cerebral vascular resistance associated with a rise in Pa co, from 34 to 56 mmHg.

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Section: Discussionsupporting

confidence: 73%

Cerebral blood flow and oxidative metabolism during hypoxia and asphyxia in the new‐born calf and lamb.

Gardiner¹

1980

The Journal of Physiology

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“…In animals with lower Po 2 at respiratory arrest, brain blood supply during hypoxia increased to a greater extent, which allowed them to resist low blood oxygenation, since increased volume blood flow maintained tissue Po 2 abo ve critical level for a long time [4,11,12].…”

Section: Resultsmentioning

confidence: 99%

Changes in hemodynamics and respiration in animals with different resistance to acute hypoxia

1999

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We studied the effects of acute hypoxia on hemodynamics and respiration in cats. The animals were divided into high-, low-and medium-resistant to hypoxia by the time of respiratory arrest after breathing with 3% 02 gas mixture. In high-resistant animals, hemodynamic indices remained at a high level throughout the hypoxic episode, while in low-resistant cats they decreased shortly after the onset of hypoxia. It is suggested that the peculiarities of hemodynamic regulation play an important role in individual resistance to acute hypoxia. Key Words: acute hypoxia; hemodynamics; respiration; individual resistance to hypoxia, ultrasound techniquesRecent studies have confirmed the existence of individual, apart from species-specific sensitivity to hypoxia. Special normobaric and hypobaric tests make it possible to classify the animals as high-(HR), medium-(MR) and low-resistant (LR) to hypoxia [1][2][3]6,9]. Biochemical studies showed that animals with different resistance to hypoxia differ not only in parameters of energy, lipid, and carbohydrate metabolism [2,6], but also in the functional characteristics of hemodynamic regulation. However, complex analyses of cardiovascular resistance to different variants of hypoxia have not yet been performed.The aim of this study was to investigate the effect of acute hypoxic hypoxia on hemodynamics and respiration in HR, MR, and LR animals. MATERIALS AND METHODSAcute experiments were carried out on 35 male and female cats (1.8-4.4 kg) anesthetized with Nembutal with an ultrasound technique. Blood pressure in the femoral and pulmonary arteries (BP) was measured with an electric manometer [7]. Ultrasonic transducers were placed on the corresponding vessels during open thorax surgery under conditions of artificial ventilation (AV), then the tissues were sutured, and the animal was switched to natural ventilation. Respiratory movements were recorded with a strain transducer. The recorded indices were analyzed on line with a microcomputer to calculate total peripheral and pulmonary vascular resistance, heart rate (HR), stroke volume, and cardiac index. Changes in the cerebral blood supply were analyzed in 8 experiments. The linear and volume blood flow velocities in the common carotid and internal maxillary arteries were studied using miniature ultrasonic transducers with an inner diameter of 1.5 and 0.5 ram. In some experiments the arterial gasses were analyzed according to the method of Astroup--Ziggard--Andersen.Individual resistance to hypoxia was measured by the time from the onset of respiration with 3% O z in nitrogen to respiratory arrest (apnea). Then the gas flow was stopped for 2-3 rain. was discontinued and the recovery of respiration was awaited for the following 2-3 min. If spontaneous respiration did not recover, the animals were ventilated artificially until the appearance of spontaneous inspirations.0007 -4888/99/0009-0906522.00 ~ Kluwer Academic/Plenum Publishers

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“…Many theories dealing with the cognitive decline in human aging emphasize the role of cerebral vascular fac tors, suggesting age-related alterations in the circulatory system contribute to the cognitive impairments of the aged by reducing cerebral blood flow and brain energy metabolism [Bircher et al, 1971]. In this section the effects of these drugs are shown.…”

Section: Othersmentioning

confidence: 99%

Drug Influences on Learning and Memory in Aged Animals and Humans

Hock¹

1987

Neuropsychobiology

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In this article the effects of neurotransmitter systems or specific drugs on cognitive functions of aged animals and humans are reviewed. While there have been used many different pharmacologic and behavioral approaches to treat and test cognitive deficits in aged animals and geriatric or demented patients, there is still the question of the validity of animal models of human disorders. Attempts are made to show that there are parallels and similarities. These similarities suggest that the neurological and neurochemical changes observed may play common roles in similar behavioral deficits observed in aged animals and humans.

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Effect of microcirculation changes on brain tissue oxygenation

Cited by 35 publications

References 18 publications

Cerebral blood flow and oxidative metabolism during hypoxia and asphyxia in the new‐born calf and lamb.

Cerebral blood flow and oxidative metabolism during hypoxia and asphyxia in the new‐born calf and lamb.

Changes in hemodynamics and respiration in animals with different resistance to acute hypoxia

Drug Influences on Learning and Memory in Aged Animals and Humans

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