Arteriolar oxygenation in tumour and subcutaneous arterioles: effects of inspired air oxygen content.

M. W. Dewhirst, E. T. Ong, G. L. Rosner, S. W. Rehmus, S. Shan, R. D. Braun, D. M. Brizel, Timothy W Secomb

Research output: Contribution to journalArticle

Abstract

Carbogen is thought to be more effective than normobaric oxygen in reducing tumour hypoxia because it may reduce hyperoxic vasoconstriction. In this study, tumour and normal arteriolar diameters were measured simultaneously with perivascular pO2 during air breathing followed by either carbogen or 100% oxygen to determine whether the action of carbogen is the result of alterations in feeding vessel diameter. Fischer-344 rats bearing dorsal flap window chambers, with or without implanted R3230AC tumours, were the experimental subjects. Arteriolar diameters were measured using optical techniques and perivascular pO2 was measured using recessed-tip electrodes (3-6 microns tip diameter). Baseline arteriolar pO2 averaged 30-50% of blood gas pO2 (mean = 97 mmHg). Both hyperoxic gases increased blood gas pO2 by 4-to 5-fold, but relative improvements in arteriolar pO2 were < or = 2.5 for all arterioles studied. This means that these normobaric high O2 gases are not very efficient in increasing O2 delivery to tumours. In addition, improvements in tumour arteriolar pO2 were transient for both hyperoxic gases. Oxygen and carbogen caused no change and mild vasodilatory responses in tumour arterioles, respectively. Normal arterioles on the other hand, tended toward vasoconstriction by carbogen breathing. Peri-arteriolar pO2 in tumours increased within the first 5 min of breathing either hyperoxic gas, followed by a decline back toward values seen with air-breathing. These results suggest that temporal changes in tumour oxygenation after exposure to carbogen or O2 may not be due to changes in perfusion. Other factors, such as changes in O2 consumption rate may be involved.

Original languageEnglish (US)
JournalThe British journal of cancer. Supplement
Volume27
StatePublished - Jul 1996
Externally publishedYes

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Arterioles
Air
Oxygen
Gases
Respiration
Neoplasms
Vasoconstriction
Inbred F344 Rats
carbogen
Electrodes
Perfusion

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Arteriolar oxygenation in tumour and subcutaneous arterioles : effects of inspired air oxygen content. / Dewhirst, M. W.; Ong, E. T.; Rosner, G. L.; Rehmus, S. W.; Shan, S.; Braun, R. D.; Brizel, D. M.; Secomb, Timothy W.

In: The British journal of cancer. Supplement, Vol. 27, 07.1996.

Research output: Contribution to journalArticle

Dewhirst, M. W. ; Ong, E. T. ; Rosner, G. L. ; Rehmus, S. W. ; Shan, S. ; Braun, R. D. ; Brizel, D. M. ; Secomb, Timothy W. / Arteriolar oxygenation in tumour and subcutaneous arterioles : effects of inspired air oxygen content. In: The British journal of cancer. Supplement. 1996 ; Vol. 27.
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abstract = "Carbogen is thought to be more effective than normobaric oxygen in reducing tumour hypoxia because it may reduce hyperoxic vasoconstriction. In this study, tumour and normal arteriolar diameters were measured simultaneously with perivascular pO2 during air breathing followed by either carbogen or 100{\%} oxygen to determine whether the action of carbogen is the result of alterations in feeding vessel diameter. Fischer-344 rats bearing dorsal flap window chambers, with or without implanted R3230AC tumours, were the experimental subjects. Arteriolar diameters were measured using optical techniques and perivascular pO2 was measured using recessed-tip electrodes (3-6 microns tip diameter). Baseline arteriolar pO2 averaged 30-50{\%} of blood gas pO2 (mean = 97 mmHg). Both hyperoxic gases increased blood gas pO2 by 4-to 5-fold, but relative improvements in arteriolar pO2 were < or = 2.5 for all arterioles studied. This means that these normobaric high O2 gases are not very efficient in increasing O2 delivery to tumours. In addition, improvements in tumour arteriolar pO2 were transient for both hyperoxic gases. Oxygen and carbogen caused no change and mild vasodilatory responses in tumour arterioles, respectively. Normal arterioles on the other hand, tended toward vasoconstriction by carbogen breathing. Peri-arteriolar pO2 in tumours increased within the first 5 min of breathing either hyperoxic gas, followed by a decline back toward values seen with air-breathing. These results suggest that temporal changes in tumour oxygenation after exposure to carbogen or O2 may not be due to changes in perfusion. Other factors, such as changes in O2 consumption rate may be involved.",
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AU - Rosner, G. L.

AU - Rehmus, S. W.

AU - Shan, S.

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