scholarly journals Decreased arterial PO2, not O2content, increases blood flow through intrapulmonary arteriovenous anastomoses at rest

2016 ◽  
Vol 594 (17) ◽  
pp. 4981-4996 ◽  
Author(s):  
Joseph W. Duke ◽  
James T. Davis ◽  
Benjamin J. Ryan ◽  
Jonathan E. Elliott ◽  
Kara M. Beasley ◽  
...  
Keyword(s):  
Blood Flow ◽  
Arteriovenous Anastomoses ◽  
Flow Through ◽  
Arterial Po2

The selective closure of feline carotid arteriovenous anastomoses (AVAs) by GR43175

Cephalalgia ◽  
1989 ◽  
Vol 9 (9_suppl) ◽  
pp. 41-46
Author(s):  
Marion J Perren ◽  
Wasyl Feniuk ◽  
Patrick Pa Humphrey
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Peripheral Resistance ◽  
Haemodynamic Effects ◽  
Arterial Blood Flow ◽  
Arteriovenous Anastomoses ◽  
Arterial Blood ◽  
Flow Through ◽  
Carotid Arterial ◽  
Dose Dependent

The haemodynamic effects of the selective 5-HT1-like agonist GR43175 have been compared with that of ergotamine in anaesthetized cats. Both GR43175 (30–1000 μg/kg intravenously) and ergotamine (0.3–30 μg/kg intravenously) caused a dose-dependent reduction in the proportion of cardiac output passing through arteriovenous anastomoses (AVAs). However, unlike GR43175, the effect of ergotamine (30 μg/kg intravenously) was associated with marked increases in diastolic blood pressure and total peripheral resistance. In further studies, the effect of GR43175 on the distribution of blood flow within the carotid bed has been examined. GR43175 caused a reduction in total carotid arterial blood flow which was entirely due to a reduction in flow through carotid AVAs. These results demonstrate that GR43175, unlike ergotamine, has a highly selective vasoconstrictor action on AVAs within the cranial circulation of anaesthetized cats. Such a mechanism may be important in its antimigraine activity.

scholarly journals Decreased Arterial PO 2 , not O 2 Content, Increases Blood Flow Through Intrapulmonary Arteriovenous Anastomoses at Rest

2015 ◽  
Vol 29 (S1) ◽  
Author(s):  
Joseph Duke ◽  
Benjamin Ryan ◽  
James Davis ◽  
Kara Beasley ◽  
Frank Petrassi ◽  
...  
Keyword(s):  
Blood Flow ◽  
Arteriovenous Anastomoses ◽  
Flow Through

scholarly journals Quantification of reduced blood flow through intrapulmonary arteriovenous anastomoses in healthy humans during exercise breathing 100% O 2

2013 ◽  
Vol 27 (S1) ◽  
Author(s):  
Steven Laurie ◽  
Jonathan E. Elliott ◽  
Joseph W Duke ◽  
Randall D Goodman ◽  
Igor M Gladstone ◽  
...  
Keyword(s):  
Blood Flow ◽  
Arteriovenous Anastomoses ◽  
Healthy Humans ◽  
Flow Through

scholarly journals Breathing 100% O 2 , but not 40% O 2 , during exercise reduces blood flow through intrapulmonary arteriovenous anastomoses (1175.7)

2014 ◽  
Vol 28 (S1) ◽  
Author(s):  
James Davis ◽  
Jonathan Elliot ◽  
Joseph Duke ◽  
Joel Futral ◽  
Andrew Lovering
Keyword(s):  
Blood Flow ◽  
Arteriovenous Anastomoses ◽  
Flow Through

Relationship between quantitative and descriptive methods of studying blood flow through intrapulmonary arteriovenous anastomoses during exercise

2017 ◽  
Vol 243 ◽  
pp. 47-54 ◽  
Author(s):  
Joseph W. Duke ◽  
Jonathan E. Elliott ◽  
Steven S. Laurie ◽  
Thomas Voelkel ◽  
Igor M. Gladstone ◽  
...  
Keyword(s):  
Blood Flow ◽  
Arteriovenous Anastomoses ◽  
Flow Through

Cerebral blood flow in birds: effect of hypoxia

1978 ◽  
Vol 234 (3) ◽  
pp. H230-H234 ◽  
Author(s):  
B. Grubb ◽  
J. M. Colacino ◽  
K. Schmidt-Nielsen
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Arterial Oxygen Tension ◽  
Arterial Oxygen ◽  
Two Component ◽  
Flow Through ◽  
Oxygen Tensions ◽  
Xenon 133 ◽  
Arterial Po2 ◽  
Increased Blood Flow

The effect of hypoxia on cerebral blood flow in ducks was investigated by the rate at which arterially injected xenon-133 was cleared from the duck's brain. A two-component clearance curve resulted, which we have attributed to flow through the grey and white matter. Decreasing the arterial oxygen tension (PaO2) to 75 mmHg had no effect on cerebral blood flow. However, decreasing the PaO2 below 75 mmHg significantly increased blood flow to the fast-clearing compartment. The greatest increase in blood flow was seen when the arterial PO2 was below 50 mmHg. At an arterial PO2 of 30 mmHg, the cerebral blood flow to the fast-clearing compartment was increased more than 600% above the normoxic level. The magnitude of this increase is much greater in the duck than has been reported for mammals at roughly equivalent arterial oxygen tensions. The ability of avian cerebral blood flow to increase at moderate levels of hypoxia, plus the magnitude of the increase, may play a role in the exceptional tolerance of birds to hypoxia.

scholarly journals AltitudeOmics: effect of reduced barometric pressure on detection of intrapulmonary shunt, pulmonary gas exchange efficiency, and total pulmonary resistance

2018 ◽  
Vol 124 (5) ◽  
pp. 1363-1376 ◽  
Author(s):  
Frank A. Petrassi ◽  
James T. Davis ◽  
Kara M. Beasley ◽  
Oghenero Evero ◽  
Jonathan E. Elliott ◽  
...  
Keyword(s):  
Blood Flow ◽  
Gas Exchange ◽  
Sea Level ◽  
Oxygen Tension ◽  
Pulmonary Blood Flow ◽  
Contrast Echocardiography ◽  
Barometric Pressure ◽  
Arteriovenous Anastomoses ◽  
Pulmonary Resistance ◽  
Flow Through

Blood flow through intrapulmonary arteriovenous anastomoses (QIPAVA) occurs in healthy humans at rest and during exercise when breathing hypoxic gas mixtures at sea level and may be a source of right-to-left shunt. However, at high altitudes, QIPAVA is reduced compared with sea level, as detected using transthoracic saline contrast echocardiography (TTSCE). It remains unknown whether the reduction in QIPAVA (i.e., lower bubble scores) at high altitude is due to a reduction in bubble stability resulting from the lower barometric pressure (PB) or represents an actual reduction in QIPAVA. To this end, QIPAVA, pulmonary artery systolic pressure (PASP), cardiac output (QT), and the alveolar-to-arterial oxygen difference (AaDO2) were assessed at rest and during exercise (70–190 W) in the field (5,260 m) and in the laboratory (1,668 m) during four conditions: normobaric normoxia (NN; [Formula: see text] = 121 mmHg, PB = 625 mmHg; n = 8), normobaric hypoxia (NH; [Formula: see text] = 76 mmHg, PB = 625 mmHg; n = 7), hypobaric normoxia (HN; [Formula: see text] = 121 mmHg, PB = 410 mmHg; n = 8), and hypobaric hypoxia (HH; [Formula: see text] = 75 mmHg, PB = 410 mmHg; n = 7). We hypothesized QIPAVA would be reduced during exercise in isooxic hypobaria compared with normobaria and that the AaDO2 would be reduced in isooxic hypobaria compared with normobaria. Bubble scores were greater in normobaric conditions, but the AaDO2 was similar in both isooxic hypobaria and normobaria. Total pulmonary resistance (PASP/QT) was elevated in HN and HH. Using mathematical modeling, we found no effect of hypobaria on bubble dissolution time within the pulmonary transit times under consideration (<5 s). Consequently, our data suggest an effect of hypobaria alone on pulmonary blood flow. NEW & NOTEWORTHY Blood flow through intrapulmonary arteriovenous anastomoses, detected by transthoracic saline contrast echocardiography, was reduced during exercise in acute hypobaria compared with normobaria, independent of oxygen tension, whereas pulmonary gas exchange efficiency was unaffected. Modeling the effect(s) of reduced air density on contrast bubble lifetime did not result in a significantly reduced contrast stability. Interestingly, total pulmonary resistance was increased by hypobaria, independent of oxygen tension, suggesting that pulmonary blood flow may be changed by hypobaria.

Thermal control of blood flow through capillaries and arteriovenous anastomoses in skin of sheep

1978 ◽  
Vol 378 (1) ◽  
pp. 55-63 ◽  
Author(s):  
J. R. S. Hales ◽  
A. A. Fawcett ◽  
J. W. Bennett ◽  
A. D. Needham
Keyword(s):  
Blood Flow ◽  
Thermal Control ◽  
Arteriovenous Anastomoses ◽  
Flow Through
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