Autonomic control of bronchial blood flow and airway dimensions during strenuous exercise in sheep

2007 ◽  
Vol 20 (2) ◽  
pp. 190-199 ◽  
Author(s):  
A. Quail ◽  
S. McIlveen ◽  
R. Bishop ◽  
D. McLeod ◽  
R. Gunther ◽  
...  
Keyword(s):  
Blood Flow ◽  
Autonomic Control ◽  
Strenuous Exercise ◽  
Airway Dimensions

scholarly journals Integrated autonomic control of bronchial blood flow and third generation airway dimensions during exercise

2010 ◽  
Vol 24 (S1) ◽  
Author(s):  
Saxon William White ◽  
Damian McLeod ◽  
Anthony Quail ◽  
David Cottee ◽  
Koullis Pitsillides ◽  
...  
Keyword(s):  
Blood Flow ◽  
Autonomic Control ◽  
Third Generation ◽  
Airway Dimensions

Autonomic control of cerebral blood flow: Fundamental comparisons between peripheral and cerebrovascular circulations in humans

2021 ◽  
Author(s):  
Jodie L. Koep ◽  
Chloe E. Taylor ◽  
Jeff S. Coombes ◽  
Bert Bond ◽  
Philip N. Ainslie ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Autonomic Control

Exercise-induced cardiac hypertrophy: a correlation of blood flow and microvasculature

1986 ◽  
Vol 60 (4) ◽  
pp. 1259-1267 ◽  
Author(s):  
E. A. Breisch ◽  
F. C. White ◽  
L. E. Nimmo ◽  
M. D. McKirnan ◽  
C. M. Bloor
Keyword(s):  
Blood Flow ◽  
Aortic Pressure ◽  
Left Ventricular ◽  
Treadmill Running ◽  
Adenosine Infusion ◽  
Strenuous Exercise ◽  
Luminal Surface ◽  
Trained Group ◽  
Cross Sectional ◽  
Maximum Exercise

The effects of exercise conditioning on the myocardium were studied in seven instrumented pigs strenuously exercised for 12 wk by treadmill running. Data were compared with eight instrumented untrained pigs. O2 consumption measured during maximum exercise effort was significantly elevated in the trained pigs (71.7 +/- 4.0 vs. 56.3 +/- 3.0 ml X ml-1 X kg-1). Absolute right and left ventricular mass increased by 20 and 13%, respectively, in response to exercise. Myocyte cross-sectional area increased by 21% in the trained hearts compared with the untrained hearts. Transmural left ventricular myocardial blood flow (ml X min-1 X g-1) was not significantly different at rest, during maximum exercise, or during exercise with adenosine infusion. However, training caused an elevation of the regional epicardial blood flow noted during exercise and exercise with adenosine. In the trained pigs mean aortic pressure during maximum exercise with adenosine infusion was not significantly different compared with untrained pigs. Coronary resistance during exercise with adenosine infusion was the same in both animal groups. In the trained group capillary numerical (no./mm2) and length (mm/mm3) densities were reduced, whereas arteriolar numerical and length densities were significantly increased compared with the untrained group. Measurements of capillary luminal surface density (mm2/mm3) in the trained group were unchanged compared with the untrained group. These results suggest that strenuous exercise does not stimulate the production of new capillaries, but this is modified by the ability of existing capillaries to increase their luminal surface area to parallel increases in myocyte growth. The arteriolar data suggest that exercise promotes the formation of new arterioles.(ABSTRACT TRUNCATED AT 250 WORDS)

Autonomic Control of Cerebral Blood Flow and Autoregulation

1975 ◽  
pp. 462-465 ◽  
Author(s):  
M. J. Hernández-Pérez ◽  
H. H. Erickson ◽  
E. L. Fitzpatrick
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Autonomic Control

Effects of graded exercise on bronchial blood flow and airway dimensions in sheep

2007 ◽  
Vol 20 (2) ◽  
pp. 178-189 ◽  
Author(s):  
R. Bishop ◽  
D. McLeod ◽  
S. McIlveen ◽  
R. Blake ◽  
R. Gunther ◽  
...  
Keyword(s):  
Blood Flow ◽  
Graded Exercise ◽  
Airway Dimensions

Coronary physiology

1983 ◽  
Vol 63 (1) ◽  
pp. 1-205 ◽  
Author(s):  
E. O. Feigl
Keyword(s):  
Blood Flow ◽  
Metabolic Control ◽  
Coronary Blood Flow ◽  
Oxygen Tension ◽  
Nerve Stimulation ◽  
Left Ventricular ◽  
Strenuous Exercise ◽  
Unexpected Finding ◽  
Coronary Vasoconstriction ◽  
Coronary Physiology

The major areas of normal coronary physiological research since Berne's 1964 review have been the measurement of ventricular transmural blood flow distribution with microspheres, the adenosine hypothesis of local metabolic control of coronary blood flow, and the autonomic control of coronary blood flow. There is an improved understanding of intramyocardial tissue pressure and extravascular compressive forces on coronary vessels. However, the unexpected finding of zero flow during a prolonged diastole with a coronary artery pressure of 40 mmHg (PZF) is a reminder that the physical forces, including vascular smooth muscle contraction, that determine coronary vascular resistance are incompletely understood. During normal circumstances, the left ventricular subendocardium probably receives more blood flow than the subepicardium does, but the difference is small. When the coronary circulation is compromised by stenosis or aortic valve lesions, the subendocardium is much more vulnerable to underperfusion than is the subepicardium. The coronary vasodilating effect of arterial hypoxia has been confirmed in many studies, but the role of tissue oxygen tension in local metabolic control of coronary blood flow during normoxia is unknown. The coronary vasodilating action of carbon dioxide has received renewed attention, but its role in local control is also unknown. The adenosine hypothesis has passed several critical tests, but despite much research the importance of adenosine in normal coronary regulation is not established. Local metabolic control of coronary blood flow probably involves more than just one factor, but a unified hypothesis has not been put forward. Sympathetic alpha-receptor-mediated coronary vasoconstriction has been demonstrated by nerve stimulation and during a carotid sinus baroreceptor reflex. Sympathetic coronary vasoconstriction is capable of competing with local metabolic control to lower coronary venous oxygen tension under experimental circumstances, but its importance during normal resting conditions is not established. Parasympathetic muscarinic coronary vasodilation has been shown by vagal nerve stimulation, but a role for it during normal blood flow regulation has yet to be demonstrated. There have been elegant descriptive studies of the coronary blood flow response during excitement and exercise, where coronary blood flow increases pari passu with myocardial metabolism; however, there are also data that indicate a concomitant sympathetic vasoconstrictor effect during strenuous exercise. Overall there has been encouraging progress in coronary physiology. Inevitably new knowledge has focused old questions and presented new ones.

Cerebral blood flow and metabolism during exercise: implications for fatigue

2008 ◽  
Vol 104 (1) ◽  
pp. 306-314 ◽  
Author(s):  
Neils H. Secher ◽  
Thomas Seifert ◽  
Johannes J. Van Lieshout
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Perceived Exertion ◽  
Cerebral Oxygenation ◽  
Metabolic Response ◽  
Work Of Breathing ◽  
Whole Body ◽  
Strenuous Exercise ◽  
Glycogen Depletion ◽  
The Brain

During exercise: the Kety-Schmidt-determined cerebral blood flow (CBF) does not change because the jugular vein is collapsed in the upright position. In contrast, when CBF is evaluated by 133Xe clearance, by flow in the internal carotid artery, or by flow velocity in basal cerebral arteries, a ∼25% increase is detected with a parallel increase in metabolism. During activation, an increase in cerebral O2 supply is required because there is no capillary recruitment within the brain and increased metabolism becomes dependent on an enhanced gradient for oxygen diffusion. During maximal whole body exercise, however, cerebral oxygenation decreases because of eventual arterial desaturation and marked hyperventilation-related hypocapnia of consequence for CBF. Reduced cerebral oxygenation affects recruitment of motor units, and supplemental O2 enhances cerebral oxygenation and work capacity without effects on muscle oxygenation. Also, the work of breathing and the increasing temperature of the brain during exercise are of importance for the development of so-called central fatigue. During prolonged exercise, the perceived exertion is related to accumulation of ammonia in the brain, and data support the theory that glycogen depletion in astrocytes limits the ability of the brain to accelerate its metabolism during activation. The release of interleukin-6 from the brain when exercise is prolonged may represent a signaling pathway in matching the metabolic response of the brain. Preliminary data suggest a coupling between the circulatory and metabolic perturbations in the brain during strenuous exercise and the ability of the brain to access slow-twitch muscle fiber populations.

Hypoxia has a greater effect than exercise on the redistribution of pulmonary blood flow in swine

2007 ◽  
Vol 103 (6) ◽  
pp. 2112-2119 ◽  
Author(s):  
Susan R. Hopkins ◽  
Axel Kleinsasser ◽  
Susan Bernard ◽  
Alex Loeckinger ◽  
Eric Falor ◽  
...  
Keyword(s):  
Blood Flow ◽  
Pulmonary Blood Flow ◽  
Strenuous Exercise ◽  
Exercise Tests ◽  
Fluorescent Intensity ◽  
Pulmonary Capillaries ◽  
High Altitude Pulmonary Edema ◽  
Specific Pathogen ◽  
Pulmonary Arterial ◽  
Maximal Shift

Strenuous exercise combined with hypoxia is implicated in the development of high-altitude pulmonary edema (HAPE), which is believed to result from rupture of pulmonary capillaries secondary to high vascular pressures. The relative importance of hypoxia and exercise in altering the distribution of pulmonary blood flow (PBF) is unknown. Six chronically catheterized specific pathogen-free Yorkshire hybrid pigs (25.5 ± 0.7 kg, means ± SD) underwent incremental treadmill exercise tests in normoxia (FiO2 = 0.21) and hypoxia (FiO2 = 0.125, balanced order), consisting of 5 min at 30, 60, and 90% of the previously determined V̇o2max. At steady state (∼4 min), metabolic and cardiac output data were collected and fluorescent microspheres were injected over ∼30 s. Later the fluorescent intensity of each color in each 2-cm3 lung piece was determined and regional perfusion was calculated from the weight-normalized fluorescence. Both hypoxia and exercise shifted PBF away from the ventral cranial lung regions toward the dorsal caudal regions of the lung, but hypoxia caused a greater dorsal caudal shift in PBF at rest than did near-maximal exercise in normoxia. The variance in PBF due to hypoxia, exercise, and vascular structure was 16 ± 4.2, 4.0 ± 4.4, and 59.4 ± 11.4%, respectively, and the interaction between hypoxia and exercise represented 12 ± 6.5%. This observation implies that there is already a maximal shift with in PBF with hypoxia in the dorsal-caudal regions in pigs that cannot be exceeded with the addition of exercise. However, exercise greatly increases the pulmonary arterial pressures and therefore the risk of capillary rupture in high flow regions.

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