Integrated Measurements of Electrical Activity, Oxygen Tension, Blood Flow, and Ca2+-Signaling in Rodents In Vivo

2014 ◽  
pp. 243-264
Author(s):  
Claus Mathiesen ◽  
Kirsten Thomsen ◽  
Martin Lauritzen
Keyword(s):  
Blood Flow ◽  
Electrical Activity ◽  
Oxygen Tension

Critical P O 2 of skeletal muscle in vivo

1999 ◽  
Vol 277 (5) ◽  
pp. H1831-H1840 ◽  
Author(s):  
Keith N. Richmond ◽  
Ross D. Shonat ◽  
Ronald M. Lynch ◽  
Paul C. Johnson
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Oxygen Tension ◽  
Muscle Blood Flow ◽  
Interstitial Oxygen ◽  
Local Conditions ◽  
Phosphorescence Lifetime ◽  
Nadh Fluorescence

The main purpose of this study was to determine the interstitial oxygen tension at which aerobic metabolism becomes limited (critical [Formula: see text]) in vivo in resting skeletal muscle. Using an intravital microscope system, we determined the interstitial oxygen tension at 20-μm-diameter tissue sites in rat spinotrapezius muscle from the phosphorescence lifetime decay of a metalloporphyrin probe during a 1-min stoppage of muscle blood flow. In paired experiments NADH fluorescence was measured at the same sites during flow stoppage. NADH fluorescence rose significantly above control when interstitial[Formula: see text] fell to 2.9 ± 0.5 mmHg ( n = 13) and was not significantly different (2.4 ± 0.5 mmHg) when the two variables were first averaged for all sites and then compared. Similar values were obtained using the abrupt change in rate of[Formula: see text] decline as the criterion for critical [Formula: see text]. With a similar protocol, we determined that NADH rose significantly at a tissue site centered 30 μm from a collecting venule when intravascular[Formula: see text] fell to 7.2 ± 1.5 mmHg. The values for critical interstitial and critical intravascular[Formula: see text] are well below those reported during free blood flow in this and in other muscle preparations, suggesting that oxygen delivery is regulated at levels well above the minimum required for oxidative metabolism. The extracellular critical[Formula: see text] found in this study is slightly greater than previously found in vitro, possibly due to differing local conditions rather than a difference in metabolic set point for the mitochondria.

Microvascular features that suggest effectors of blood-flow regulation in the brain: Evidence by SEM of corrosion casts of intracerebral vessels

1990 ◽  
Vol 48 (3) ◽  
pp. 274-275
Author(s):  
Enrico D.F. Motti ◽  
Hans-Georg Imhof ◽  
Gazi M. Yasargil
Keyword(s):  
Blood Flow ◽  
Perfusion Pressure ◽  
Corrosion Casts ◽  
Cerebral Microcirculation ◽  
Pial Arteries ◽  
Random Occurrence ◽  
Brain Arteries ◽  
Homogeneous Network ◽  
The Brain

Physiologists have devoted most attention in the cerebrovascular tree to the arterial side of the circulation which has been subdivided in three levels: 1) major brain arteries which keep microcirculation constant despite changes in perfusion pressure; 2) pial arteries supposed to be effectors regulating microcirculation; 3) intracerebral arteries supposed to be deprived of active cerebral blood flow regulating devices.The morphological search for microvascular effectors in the cerebrovascular bed has been elusive. The opaque substance of the brain confines in vivo investigation to the superficial pial arteries. Most morphologists had to limit their observation to the random occurrence of a favorable site in the practically two-dimensional thickness of diaphanized histological sections. It is then not surprising most investigators of the cerebral microcirculation refer to an homogeneous network of microvessels interposed between arterioles and venules.We have taken advantage of the excellent depth of focus afforded by the scanning electron microscope (SEM) to investigate corrosion casts obtained injecting a range of experimental animals with a modified Batson's acrylic mixture.

Fit Vs Faint: Assessing Work Causation in “Idiopathic Fall” Cases

2014 ◽  
Vol 19 (5) ◽  
pp. 3-12
Author(s):  
Lorne Direnfeld ◽  
David B. Torrey ◽  
Jim Black ◽  
LuAnn Haley ◽  
Christopher R. Brigham
Keyword(s):  
Blood Flow ◽  
Electrical Activity ◽  
Loss Of Consciousness ◽  
Brain Electrical Activity ◽  
Medical Terminology ◽  
Scientific Analysis ◽  
Medical Causation ◽  
The Individual ◽  
The Brain ◽  
Current Science

Abstract When an individual falls due to a nonwork-related episode of dizziness, hits their head and sustains injury, do workers’ compensation laws consider such injuries to be compensable? Bearing in mind that each state makes its own laws, the answer depends on what caused the loss of consciousness, and the second asks specifically what happened in the fall that caused the injury? The first question speaks to medical causation, which applies scientific analysis to determine the cause of the problem. The second question addresses legal causation: Under what factual circumstances are injuries of this type potentially covered under the law? Much nuance attends this analysis. The authors discuss idiopathic falls, which in this context means “unique to the individual” as opposed to “of unknown cause,” which is the familiar medical terminology. The article presents three detailed case studies that describe falls that had their genesis in episodes of loss of consciousness, followed by analyses by lawyer or judge authors who address the issue of compensability, including three scenarios from Arizona, California, and Pennsylvania. A medical (scientific) analysis must be thorough and must determine the facts regarding the fall and what occurred: Was the fall due to a fit (eg, a seizure with loss of consciousness attributable to anormal brain electrical activity) or a faint (eg, loss of consciousness attributable to a decrease in blood flow to the brain? The evaluator should be able to fully explain the basis for the conclusions, including references to current science.

Effect of caffeine on theophyliine on cerebral blood flow response to brain activation: In vitro and in vivo studies

2005 ◽  
Vol 25 (1_suppl) ◽  
pp. S198-S198
Author(s):  
Joseph R Meno ◽  
Thien-son K Nguyen ◽  
Elise M Jensen ◽  
G Alexander West ◽  
Leonid Groysman ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Brain Activation ◽  
In Vivo Studies ◽  
Blood Flow Response ◽  
Flow Response

Observations on the Accuracy of Photometric Techniques Used to Measure Some In Vivo Microvascular Blood Flow Parameters

1998 ◽  
Vol 5 (1) ◽  
pp. 61-70 ◽  
Author(s):  
GILES R COKELET ◽  
AXEL R PRIES ◽  
MOHAMMAD F KIANI
Keyword(s):  
Blood Flow ◽  
Microvascular Blood Flow ◽  
Flow Parameters

Effects of NO-Donors on Thrombus Formation and Microcirculation in Cerebral Vessels of the Rat

1996 ◽  
Vol 76 (01) ◽  
pp. 111-117 ◽  
Author(s):  
Yasuto Sasaki ◽  
Junji Seki ◽  
John C Giddings ◽  
Junichiro Yamamoto
Keyword(s):  
Blood Flow ◽  
Thrombus Formation ◽  
Dependent Manner ◽  
Red Cell ◽  
Cell Velocity ◽  
Red Cell Velocity ◽  
The Mean ◽  
Wall Shear ◽  
Dose Dependent

SummarySodium nitroprusside (SNP) and 3-morpholinosydnonimine (SIN-1), are known to liberate nitric oxide (NO). In this study the effects of SNP and SIN-1 on thrombus formation in rat cerebral arterioles and venules in vivo were assessed using a helium-neon (He-Ne) laser. SNP infused at doses from 10 Μg/kg/h significantly inhibited thrombus formation in a dose dependent manner. This inhibition of thrombus formation was suppressed by methylene blue. SIN-1 at a dose of 100 Μg/kg/h also demonstrated a significant antithrombotic effect. Moreover, treatment with SNP increased vessel diameter in a dose dependent manner and enhanced the mean red cell velocity measured with a fiber-optic laser-Doppler anemometer microscope (FLDAM). Blood flow, calculated from the mean red cell velocity and vessel diameters was increased significantly during infusion. In contrast, mean wall shear rates in the arterioles and venules were not changed by SNP infusion. The results indicated that SNP and SIN-1 possessed potent antithrombotic activities, whilst SNP increased cerebral blood flow without changing wall shear rate. The findings suggest that the NO released by SNP and SIN-1 may be beneficial for the treatment and protection of cerebral infarction

Factors Influencing Leukocyte Adherence in Microvessels

1977 ◽  
Vol 38 (04) ◽  
pp. 0823-0830 ◽  
Author(s):  
Mayrovttz N. Harvey ◽  
Wiedeman P. Mary ◽  
Ronald F. Tuma
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Tissue Injury ◽  
Threshold Value ◽  
In Vivo Studies ◽  
Leukocyte Adherence ◽  
Rolling Velocity ◽  
Subsequent Behavior ◽  
Flow Stasis

SummaryIn vivo studies of the microcirculation of an untraumatized and unanesthetized animal preparation has shown that leukocyte adherence to vascular endothelium is an extremely rare occurrence. Induction of leukocyte adherence can be produced in a variety of ways including direct trauma to the vessels, remote tissue injury via laser irradiation, and denuding the epithelium overlying the observed vessels. The role of blood flow and local hemodynamics on the leukocyte adherence process is quite complex and still not fully understood. From the results reported it may be concluded that blood flow stasis will not produce leukocyte adherence but will augment pre-existing adherence. Studies using 2 quantitative measures of adherence, leukocyte flux and leukocyte velocity have shown these parameters to be affected differently by local hemodynamics. Initial adherence appears to be critically dependent on the magnitude of the blood shear stress at the vessel wall as evidenced by the lack of observable leukocyte flux above some threshold value. Subsequent behavior of the leukocytes as characterized by their average rolling velocity shows no apparent relationship to shear stress but, for low velocities, may be related to the linear blood velocity.

An in vivo Model for the Assessment of Acute Fibrinolytic Capacity of the Endothelium

1997 ◽  
Vol 78 (04) ◽  
pp. 1242-1248 ◽  
Author(s):  
David E Newby ◽  
Robert A Wright ◽  
Christopher A Ludlam ◽  
Keith A A Fox ◽  
Nicholas A Boon ◽  
...  
Keyword(s):  
Blood Flow ◽  
Substance P ◽  
Sodium Nitroprusside ◽  
Plasma Concentrations ◽  
In Vivo Model ◽  
Forearm Circulation ◽  
Von Willebrand ◽  
Local Release ◽  
Willebrand Factor

SummaryThe effects on blood flow and plasma fibrinolytic and coagulation parameters of intraarterial substance P, an endothelium dependent vasodilator, and sodium nitroprusside, a control endothelium independent vasodilator, were studied in the human forearm circulation. At subsystemic locally active doses, both substance P (2-8 pmol/min) and sodium nitroprusside (2-8 μg/min) caused dose-dependent vasodilatation (p <0.001 for both) without affecting plasma concentrations of PAI-1, von Willebrand factor antigen or factor VIII:C activity. Substance P caused local increases in t-PA antigen and activity (p <0.001) in the infused arm while sodium nitroprusside did not. At higher doses, substance P increased blood flow and t-PA concentrations in the noninfused arm. We conclude that brief, locally active and subsystemic infusions of intraarterial substance P cause a rapid and substantial local release of t-PA which appear to act via a flow and nitric oxide independent mechanism. This model should provide a useful and selective method of assessing the in vivo capacity of the forearm endothelium to release t-PA acutely.

Platelet Adhesion in Polytetrafluoroethylene (PTFE) Vascular Grafts In Vivo and the Influence of Increased Intramuscular Pressure-An Experimental Model

1983 ◽  
Vol 50 (04) ◽  
pp. 881-884 ◽  
Author(s):  
J T Christenson ◽  
P Qvarfordt ◽  
S-E Strand ◽  
D Arvidsson ◽  
T Sjöberg ◽  
...  
Keyword(s):  
Blood Flow ◽  
Graft Failure ◽  
Small Diameter ◽  
Graft Material ◽  
Intramuscular Pressure ◽  
Initial Flow ◽  
Early Graft ◽  
Wick Technique ◽  
Early Graft Failure

SummaryThrombogenicity of graft material is involved in early graft failure in small diameter grafts. The frequently seen postoperative swelling of the leg after distal revascularization may cause an increased intramuscular pressure and early graft failure.Pairs of 4 mm polytetrafluoroethylene (PTFE) grafts were implanted. Autologous platelets were labeled with mIn-oxine. Platelet adhesiveness onto the grafts were analyzed from gamma camera images. Intramuscular pressures were measured with wick technique. Blood flow was measured. One graft served as control the other as test graft. Ninety minutes after declamping the i. m. pressure was increased in the test-leg to 30 mmHg, and later to 60 mmHg.In the control-graft platelet uptake increased to a maximum 60 min after declamping. Blood flow and i.m. pressure remained uneffected. The test-grafts were initially similar but when i.m. pressure was increased to 30 mmHg activity in the grafts increased significantly. Blood flow decreased with 12% of initial flow. When i. m. pressure was raised to 60 mmHg platelet uptake continued to increase.An increased intramuscular pressure of 30 mmHg or more significantly increase the amount of platelets adhering onto PTFE grafts, emphasizing the need for measuring intramuscular pressures after lower limb vascular revascularizations.

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