Body temperature control of rat tail blood flow

1983 ◽  
Vol 245 (3) ◽  
pp. R426-R432 ◽  
Author(s):  
E. R. Raman ◽  
M. F. Roberts ◽  
V. J. Vanhuyse
Keyword(s):  
Blood Flow ◽  
Heat Exchange ◽  
Body Temperature ◽  
Heat Flow ◽  
Thermal Conductance ◽  
Venous Occlusion ◽  
Albino Rats ◽  
Blood Flows ◽  
Rat Tail ◽  
Tail Blood

Tail blood flow (BF) and heat flow (HF) were measured in five albino rats during transients in rectal temperature (Tre) caused by body heating at rest. During heating, tail temperature (Tt) was kept at 15, 20, 25, 30, 35, or 42 degrees C by enclosing the tail in a water-perfused tube. Thermal conductance (K) was computed as HF/(Tre-Tt). BF was measured by venous occlusion plethysmography. Heating caused a rise in Tre that was accompanied by proportional increases in both K and BF. The ratio R = K/BF represents conductance per unit BF and reflects the amount of heat exchange for a given BF. R can thus be used to estimate the distribution of BF within the tail. R was independent of Tre at all Tt, indicating that BF distribution is controlled by the tail. R was low at low Tt and rose at higher Tt. This suggests that at low Tt, blood flows primarily in central veins of the tail and at higher Tt blood flows in peripheral tail veins.

Maximal vascular leg conductance in trained and untrained men

1987 ◽  
Vol 62 (2) ◽  
pp. 606-610 ◽  
Author(s):  
P. G. Snell ◽  
W. H. Martin ◽  
J. C. Buckey ◽  
C. G. Blomqvist
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Oxygen Uptake ◽  
Maximal Oxygen Uptake ◽  
Reactive Hyperemia ◽  
Venous Occlusion ◽  
Vascular Conductance ◽  
Blood Flows ◽  
Arterial Blood ◽  
Sedentary Subjects

Lower leg blood flow and vascular conductance were studied and related to maximal oxygen uptake in 15 sedentary men (28.5 +/- 1.2 yr, mean +/- SE) and 11 endurance-trained men (30.5 +/- 2.0 yr). Blood flows were obtained at rest and during reactive hyperemia produced by ischemic exercise to fatigue. Vascular conductance was computed from blood flow measured by venous occlusion plethysmography, and mean arterial blood pressure was determined by auscultation of the brachial artery. Resting blood flow and mean arterial pressure were similar in both groups (combined mean, 3.0 ml X min-1 X 100 ml-1 and 88.2 mmHg). After ischemic exercise, blood flows were 29- and 19-fold higher (P less than 0.001) than rest in trained (83.3 +/- 3.8 ml X min-1 X 100 ml-1) and sedentary subjects (61.5 +/- 2.3 ml X min-1 X 100 ml-1), respectively. Blood pressure and heart rate were only slightly elevated in both groups. Maximal vascular conductance was significantly higher (P less than 0.001) in the trained compared with the sedentary subjects. The correlation coefficients for maximal oxygen uptake vs. vascular conductance were 0.81 (trained) and 0.45 (sedentary). These data suggest that physical training increases the capacity for vasodilation in active limbs and also enables the trained individual to utilize a larger fraction of maximal vascular conductance than the sedentary subject.

Measurement of the cutaneous circulation

1965 ◽  
Vol 20 (4) ◽  
pp. 696-702 ◽  
Author(s):  
Harry M. Wright
Keyword(s):  
Blood Flow ◽  
Skin Temperature ◽  
Circulatory Arrest ◽  
Thermal Conductance ◽  
Venous Occlusion ◽  
Indirect Methods ◽  
Blood Content ◽  
Heating And Cooling ◽  
Flow Through ◽  
Cutaneous Circulation

Relationships between four commonly used indirect methods for study of the cutaneous circulation in intact, unanesthetized man were examined. Skin temperature, thermal conductance, volume plethysmography and the light absorption of the skin (as related to hemoglobin content) were simultaneously recorded on the upper extremities of normal young men as blood flow and blood content of the skin were changed by circulatory arrest, venous occlusion, indirect heating and cooling, and changes in position. Skin temperature and thermal conductance changed along parallel courses as blood flow was changed, while finger volume and reflectance of the skin to light of wavelength 550 mμ both changed in expected directions although along different courses, following passive congestion and de-congestion and changes in level of the hand relative to the heart. The advantages, disadvantages, and limitations of each of the methods in the study of cutaneous circulation in man are discussed and compared. measurement of circulation of skin; methods for measurement of cutaneous circulation; blood flow through skin; blood content of skin; skin Submitted on March 12, 1964

Comparison of the performance characteristics of three generations of membrane oxygenators: Univox®, Univox® Gold™ and SpiralGold™

Perfusion ◽  
1996 ◽  
Vol 11 (1) ◽  
pp. 61-70 ◽  
Author(s):  
Philip D Beckley ◽  
Susan M Morris ◽  
James J Smith ◽  
Jerri L McNamara ◽  
Julie A Novak
Keyword(s):  
Heat Transfer ◽  
Blood Flow ◽  
Heat Exchange ◽  
Blood Flows ◽  
Heparin Coating ◽  
Baxter Healthcare ◽  
Recent Addition ◽  
Flow Pressure ◽  
The Impact

With continuous enhancement in oxygenator design, the question is raised as to how these changes actually impact the performance of the oxygenator. The recent addition of two new oxygenators by the Bentley Division of Baxter Healthcare Corporation provided us with a unique opportunity to compare the performance of each device and isolate the impact of each design change on performance. While the basic design and flow patterns have remained the same, application of the Duraflo® II treatment has produced the Univox® Gold™ and a change in the fibre-winding technique has produced the SpiralGold™. This study compared the effects of heparin coating (Univox® to Univox® Gold™) and fibre-winding (Univox® Gold™ to SpiralGold™) on gas and heat transfer and resistance to blood flow (pressure drop). Six oxygenators of each model were evaluated utilizing an in vitro single pass circuit, which first conditioned bovine blood to the Association for the Advancement of Medical Instrumentation (AAMI) venous standards. Blood flows of 4.0, 5.0, 6.0 and 7.0 I/min, FiO2 values of 1.0, 0.8 and 0.6, and gas-to-blood flow ratios of 0.5, 1.0 and 1.5 were chosen as test variables. Data generated included oxygen transfer, carbon dioxide transfer, arterial pO2, resistance to blood flow, and coefficient of heat exchange. The results indicate that the Duraflo II treatment does not have a significant effect on gas and heat transfer or resistance to blood flow. The fibre-winding technique employed with the new SpiralGold™, however, has improved significantly gas exchange and arterial PO2 when compared with the previous Univox® models. Resistance to blood flow and coefficient of heat exchange were not affected significantly by the winding technique.

Effect of rhythmically inflating a pneumatic cuff at the ankle on blood flow in the foot

1959 ◽  
Vol 14 (3) ◽  
pp. 411-413 ◽  
Author(s):  
R. Andrew Loane
Keyword(s):  
Blood Flow ◽  
Heat Flow ◽  
Perfusion Pressure ◽  
Venous Pressure ◽  
Venous Occlusion ◽  
Quantitative Agreement ◽  
Venous Occlusion Plethysmography ◽  
Flow Through ◽  
And Calorimetry

Rhythmic inflation to 110 mm Hg of a pneumatic cuff around the ankle of a seated subject reduces the venous pressure in the foot and is found by three methods, venous occlusion plethysmography, heat flow and calorimetry, to increase the rate of blood flow through the foot. The increases measured by the three methods are not, however, in quantitative agreement and it is not possible to decide how large the increase may be. It is considered, however, that the increase in flow is probably of the same order as the increase in perfusion pressure and not greatly in excess of this increase. Submitted on August 5, 1958

Enhanced maximal metabolic vasodilatation in the dominant forearms of tennis players

1986 ◽  
Vol 61 (2) ◽  
pp. 673-678 ◽  
Author(s):  
L. I. Sinoway ◽  
T. I. Musch ◽  
J. R. Minotti ◽  
R. Zelis
Keyword(s):  
Blood Flow ◽  
Forearm Blood Flow ◽  
Arterial Occlusion ◽  
Study Groups ◽  
Venous Occlusion ◽  
Control Group ◽  
Tennis Players ◽  
Blood Flows ◽  
Metabolic Vasodilation ◽  
Adaptation To Exercise

In an effort to evaluate potential peripheral adaptations to training, maximal metabolic vasodilation was studied in the dominant and nondominant forearms of six tennis players and six control subjects. Maximal metabolic vasodilation was defined as the peak forearm blood flow measured after release of arterial occlusion, the reactive hyperemic blood flow (RHBF). Two ischemic stimuli were employed in each subject: 5 min of arterial occlusion (RHBF5) and 5 min of arterial occlusion coupled with 1 min of ischemic exercise (RHBF5ex). RHBF and resting forearm blood flows were measured using venous occlusion strain-gauge plethysmography (ml X min-1 X 100 ml-1). Resting forearm blood flows were similar in both arms of both groups. RHBF5ex was similar in both arms of our control group (dominant, 40.8 +/- 1.2 vs. nondominant, 40.9 +/- 2.1). However, RHBF5ex was 42% higher in the dominant than in the nondominant forearms of our tennis player population (dominant, 48.7 +/- 4.0 vs. nondominant, 34.4 +/- 3.4; P less than 0.05). This intraindividual difference in peak forearm blood flows was not secondary to improved systemic conditioning since the maximal O2 consumptions in the two study groups were similar (controls, 45.4 +/- 3.9 vs. tennis players, 46.1 +/- 1.7). These findings suggest a primary peripheral cardiovascular adaptation to exercise training in the dominant forearms of the tennis players resulting in a greater maximal vasodilatation.

Automated limb blood flow plethysmograph

1983 ◽  
Vol 244 (3) ◽  
pp. H413-H416
Author(s):  
R. R. Marcus ◽  
S. M. Horvath
Keyword(s):  
Blood Flow ◽  
Real Time ◽  
Cuff Pressure ◽  
Calculated Data ◽  
User Interaction ◽  
Venous Occlusion ◽  
Limb Blood Flow ◽  
Graphic Display ◽  
Computer Terminal ◽  
Blood Flows

An automated limb blood flow plethysmograph has been developed and interfaced to a PDP-11/60 computer. This system automatically inflates blood pressure cuffs, calibrates strain gauges, provides real-time display of limb circumference changes, and provides digital output of limb blood flow and real-time graphic display of cuff pressure. The system has been designed to require a minimum amount of user interaction by providing automatic calibration in situ, which is initiated by depressing a switch, and automatic venous cuff inflation, which initiates computer analysis of blood flow data. Digital and graphic display of blood flow is provided on a computer terminal 12 s after the start of venous occlusion. All raw data are stored on a disk for optional postexperiment analysis, which enables each blood flow curve to be graphically displayed and reanalyzed under user control. Calculated data are stored on a disk for output to a line printer at the conclusion of an experiment. A trend plot of all analyzed blood flows can be displayed on a computer terminal anytime during an experiment.

Hand circulation in the cold of Lapps and North Norwegian fishermen

1960 ◽  
Vol 15 (4) ◽  
pp. 654-658 ◽  
Author(s):  
J. Krog ◽  
B. Folkow ◽  
R. H. Fox ◽  
K. Lange Andersen
Keyword(s):  
Blood Flow ◽  
Thermal Environment ◽  
Venous Occlusion ◽  
Vascular Response ◽  
General Process ◽  
Blood Flows ◽  
Control Subjects ◽  
The Difference ◽  
Response To Temperature ◽  
Habituation To Cold

The hand blood flows of Norwegian Lapps and North Norwegian fishermen were compared with those of a group of control subjects to determine whether habituation to cold alters the local vascular response. Blood flow was measured using venous occlusion plethysmographs with local temperatures of 40°, 20°, 10°C and a few degrees above zero. In further experiments using Dewar-flask calorimeters, the rate of heat elimination and rapidity of onset of the cold vasodilatation response on immersing the hand in water at 0°C were also recorded. The subjects were kept warm in order to remove as far as possible the effects of differing degrees of vasoconstrictor fiber activity. The onset of the cold vasodilatation was found to be more rapid in the cold-habituated subjects than in the control subjects. The levels of hand blood flow were, however, the same in all three groups of subjects, implying that habituation to cold does not alter the local vascular response to temperature. It is suggested that the difference reported by other workers in similar studies are probably found only when subjects examined are partially vasoconstricted, and reflect a more general process of adaptation to cold which results in a reduced vasoconstrictor fiber activity on exposure to a given thermal environment. Submitted on August 19, 1959

Hand arterial blood flow responses to local venous congestion

1981 ◽  
Vol 240 (6) ◽  
pp. H980-H983
Author(s):  
B. I. Levy ◽  
Y. Oliva ◽  
J. P. Martineaud
Keyword(s):  
Blood Flow ◽  
Venous Occlusion ◽  
Middle Part ◽  
Venous Congestion ◽  
Arterial Blood Flow ◽  
Cuff Inflation ◽  
Blood Flows ◽  
Arterial Blood ◽  
Hand Control ◽  
Occlusion Cuff

Hand and forearm blood flows were measured in 12 subjects by means of a range-gated Doppler velocimeter, in basal conditions and after inflation (30, 50, 60, 70, and 90 mmHg) of a venous occlusion cuff on the middle part of the forearm. In basal conditions, there were significant decreases in radial, ulnar, and brachial blood flow after cuff inflation (up to -78, -69, and -31%, respectively). Minimal values were reached in less than 7 s. After occlusion of the circulation of the hand, control brachial blood flow was lowered but not significantly affected by venous distension. The results must be considered and accounted where venous occlusion plethysmography is used to measure segmental blood flow.

scholarly journals Orthostasis fails to produce active limb venoconstriction in adolescents

2001 ◽  
Vol 91 (4) ◽  
pp. 1723-1729 ◽  
Author(s):  
Julian M. Stewart ◽  
Jean Lavin ◽  
Amy Weldon
Keyword(s):  
Heart Rate ◽  
Blood Flow ◽  
Venous Occlusion ◽  
Upper Body ◽  
Sympathetic Activation ◽  
Prior Work ◽  
Blood Flows ◽  
Arterial Resistance ◽  
Capacitance Vessel ◽  
Vessel Volume

Orthostasis is characterized by translocation of blood from the upper body and thorax into dependent venous structures. Although active splanchnic venoconstriction is known to occur, active limb venoconstriction remains controversial. Based on prior work, we initially hypothesized that active venoconstriction does occur in the extremities during orthostasis in response to baroreflex activation. We investigated this hypothesis in the arms and legs of 11 healthy volunteers, aged 13–19 yr, using venous occlusion strain gauge plethysmography to obtain the forearm and calf blood flows and to compute the capacitance vessel volume-pressure compliance relation. Subjects were studied supine and at −10, +20, and +35° to load the baroreflexes. With +20° of tilt, blood flow decreased and limb arterial resistance increased significantly ( P < 0.05) compared with supine. With +35° of tilt, blood flow decreased, limb arterial resistance increased, and heart rate increased, indicating parasympathetic withdrawal and sympathetic activation with arterial vasoconstriction. The volume-pressure relation was unchanged by orthostatic maneuvers. The results suggest that active venoconstriction in the limbs is not important to mild orthostatic response.

Baroreflex control of the rat tail circulation in normothermia and hyperthermia

1989 ◽  
Vol 66 (3) ◽  
pp. 1234-1241 ◽  
Author(s):  
D. S. O'Leary ◽  
J. M. Johnson
Keyword(s):  
Venous Occlusion ◽  
Baroreflex Control ◽  
Thermal Status ◽  
In Series ◽  
Phenylephrine Infusion ◽  
Baroreceptor Reflex Control ◽  
Conscious Animals ◽  
Rat Tail ◽  
Tail Blood

The role of thermoregulatory background in the baroreceptor reflex control of the tail circulation was investigated 1) in anesthetized rats with a constant flow technique and 2) in conscious rats by measuring tail blood flow (venous occlusion plethysmography). In series I, during normothermia, systemic intravenous phenylephrine infusion increased mean arterial pressure (MAP) by 61.0 +/- 3.6 mmHg and induced a reflex decrease in tail perfusion pressure (TPP) from 105.0 +/- 6.3 to 84.2 +/- 4.4 mmHg (P less than 0.005). Hyperthermia decreased TPP to 66.5 +/- 5.1 mmHg (P less than 0.001) and abolished the TPP response to increased MAP (P greater than 0.05). Increases in MAP via systemic infusion of whole blood caused reductions in TPP during normothermia but failed to reduce TPP further during hyperthermia. Graded decreases in MAP during both normothermia and hyperthermia caused tail vasoconstriction. The increase in TPP was greater (P less than 0.025) during hyperthermia. In series II, conscious animals showed similar responses to hemorrhage. Graded decreases in MAP produced graded decreases in tail vascular conductance (TVC, ml.100 ml-1.min-1.100 mmHg-1). The slope of the TVC-MAP relationship averaged 0.011 +/- 0.003 TVC U/mmHg during normothermia and was markedly steeper (P less than 0.01) during hyperthermia (1.99 +/- 0.39 TVC U/mmHg). Thus the participation of the cutaneous vasculature of the rat in baroreceptor reflexes depends on thermal status, probably through the level of background sympathetic vasoconstrictor nerve activity.

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