Regulation of capillary blood flow and oxygen supply in skeletal muscle in dogs during hypoxaemia.

Harrison, David K.; Kessler, M.; Knauf, S.

doi:10.1113/jphysiol.1990.sp017921

Cited by 49 publications

(36 citation statements)

References 27 publications

(26 reference statements)

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“…In other words, the behaviour we have seen in individual arterioles of muscle during systemic hypoxia may explain the finding that the variation in the levels of tissue PO 2 within muscle is considerably reduced during systemic hypoxia concomitant with the fall in (92). It may also demonstrate how the O 2 consumption of resting muscle can be maintained constant during systemic hypoxia, for a more homogeneous distribution of blood flow and therefore O 2 supply through the capillary network would help muscle fibres to maintain their O 2 consumption by increasing their O 2 extraction (93).…”

Section: Interactions Between Reflex and Local Effects Of Hypoxia In mentioning

confidence: 76%

“…It is known that there is considerable variation in the level of tissue PO 2 found in different regions of skeletal muscle during normoxia (92). This reflects several factors including i) regional differences in the oxygen consumption of the nearby muscle fibres, ii) distance along the arteriolar tree from the major supplying artery given that O 2 diffuses out of arterioles along their length, and iii) proximity of arterioles and venules with opposite directions of blood flow, given that O 2 may diffuse from an arteriole to a venule, thus short-circuiting O 2 supply to tissue downstream of the arteriole.…”

Section: Interactions Between Reflex and Local Effects Of Hypoxia In mentioning

confidence: 99%

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Chemoreceptors and cardiovascular control in acute and chronic systemic hypoxia

Jm¹

1998

Braz J Med Biol Res

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This review describes the ways in which the primary bradycardia and peripheral vasoconstriction evoked by selective stimulation of peripheral chemoreceptors can be modified by the secondary effects of a chemoreceptor-induced increase in ventilation. The evidence that strong stimulation of peripheral chemoreceptors can evoke the behavioural and cardiovascular components of the alerting or defence response which is characteristically evoked by novel or noxious stimuli is considered. The functional significance of all these influences in systemic hypoxia is then discussed with emphasis on the fact that these reflex changes can be overcome by the local effects of hypoxia: central neural hypoxia depresses ventilation, hypoxia acting on the heart causes bradycardia and local hypoxia of skeletal muscle and brain induces vasodilatation. Further, it is proposed that these local influences can become interdependent, so generating a positive feedback loop that may explain sudden infant death syndrome (SIDS). It is also argued that a major contributor to these local influences is adenosine. The role of adenosine in determining the distribution of O 2 in skeletal muscle microcirculation in hypoxia is discussed, together with its possible cellular mechanisms of action. Finally, evidence is presented that in chronic systemic hypoxia, the reflex vasoconstrictor influences of the sympathetic nervous system are reduced and/or the local dilator influences of hypoxia are enhanced. In vitro and in vivo findings suggest this is partly explained by upregulation of nitric oxide (NO) synthesis by the vascular endothelium which facilitates vasodilatation induced by adenosine and other NO-dependent dilators and attenuates noradrenaline-evoked vasoconstriction. Correspondence

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Section: Interactions Between Reflex and Local Effects Of Hypoxia In mentioning

confidence: 76%

Section: Interactions Between Reflex and Local Effects Of Hypoxia In mentioning

confidence: 99%

Chemoreceptors and cardiovascular control in acute and chronic systemic hypoxia

Jm¹

1998

Braz J Med Biol Res

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“…It has also been demonstrated that hypoxaemia can directly induce vasodilation in various organs (e.g. brain, skeletal muscle) (Marshall and Metcalfe, 1989;Harrison et al, 1990;Sato et al, 1992). However, Harrison et al (1990) showed that in skeletal muscle hypoxaemia presumably leads to an increase of perfusion of larger arteries whereas capillary blood flow was only marginally improved indicating a hypoxaemia-induced higher fraction of shunt perfusion.…”

Section: Discussionmentioning

confidence: 92%

“…brain, skeletal muscle) (Marshall and Metcalfe, 1989;Harrison et al, 1990;Sato et al, 1992). However, Harrison et al (1990) showed that in skeletal muscle hypoxaemia presumably leads to an increase of perfusion of larger arteries whereas capillary blood flow was only marginally improved indicating a hypoxaemia-induced higher fraction of shunt perfusion. Such a redistribution of blood flow may also play a part in the present study in which pronounced systemic hypoxaemia is Tumour areas both in the centre and periphery were analysed.…”

Section: Discussionmentioning

confidence: 99%

Microenvironmental adaptation of experimental tumours to chronic vs acute hypoxia

et al. 2004

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This study investigated long-term microenvironmental responses (oxygenation, perfusion, metabolic status, proliferation, vascular endothelial growth factor (VEGF) expression and vascularisation) to chronic hypoxia in experimental tumours. Experiments were performed using s.c.-implanted DS-sarcomas in rats. In order to induce more pronounced tumour hypoxia, one group of animals was housed in a hypoxic atmosphere (8% O 2 ) for the whole period of tumour growth (chronic hypoxia). A second group was acutely exposed to inspiratory hypoxia for only 20 min prior to the measurements (acute hypoxia), whereas animals housed under normal atmospheric conditions served as controls. Acute hypoxia reduced the median oxygen partial pressure (pO 2 ) dramatically (1 vs 10 mmHg in controls), whereas in chronically hypoxic tumours the pO 2 was significantly improved (median pO 2 ¼ 4 mmHg), however not reaching the control level. These findings reflect the changes in tumour perfusion where acutely hypoxic tumours show a dramatic reduction of perfused tumour vessels (maybe the result of a simultaneous reduction in arterial blood pressure). In animals under chronic inspiratory hypoxia, the number of perfused vessels increased (compared to acute hypoxia), although the perfusion pattern found in control tumours was not reached. In the chronically hypoxic animals, tumour cell proliferation and tumour growth were significantly reduced, whereas no differences in VEGF expression and vascular density between these groups were observed. These results suggest that long-term adaptation of tumours to chronic hypoxia in vivo, while not affecting vascularity, does influence the functional status of the microvessels in favour of a more homogeneous perfusion.

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“…The first was carried out in mongrel dogs during stepwise increase of the stimulation frequency in a preparation similar to that already described (Harrison et al 1990). In order to interpret the results of these experiments, a second series was carried out in rabbits where the distribution of blood flow within the whole muscle at rest and during stimulation at one frequency was investigated.…”

Section: Introductionmentioning

confidence: 99%

Local oxygen supply and blood flow regulation in contracting muscle in dogs and rabbits.

Harrison

Birkenhake

Knauf

et al. 1990

The Journal of Physiology

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2. In a further model, the analysis of hydrogen clearance curves measured in the femoral vein using intravascular needle electrodes in rabbits enabled the distribution of blood flow to be evaluated both under resting conditions and during direct 2 Hz stimulation of the vastus medialis muscle.3. Increased oxygen consumption, induced by stimulation, caused increases in capillary flow which were not necessarily accompanied by augmentation of femoral artery flow.4. Po2 histograms provided no evidence of cellular anoxia even at the maximum level of oxygen consumption.5. A two-compartment distribution of flow was measured under resting conditions, whereas only one compartment could be resolved during 2 Hz stimulation of the vastus medialis muscle in the rabbit experiments. A clear redistribution of flow was observed in the absence of any increase in total flow. 6. A model for oxygen-dependent regulation of capillary blood flow involving high-flow and normal-flow compartments is proposed.

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Regulation of capillary blood flow and oxygen supply in skeletal muscle in dogs during hypoxaemia.

Cited by 49 publications

References 27 publications

Chemoreceptors and cardiovascular control in acute and chronic systemic hypoxia

Chemoreceptors and cardiovascular control in acute and chronic systemic hypoxia

Microenvironmental adaptation of experimental tumours to chronic vs acute hypoxia

Local oxygen supply and blood flow regulation in contracting muscle in dogs and rabbits.

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