Use of microspheres in measurement of regional blood flows during +GZ stress

1979 ◽  
Vol 47 (6) ◽  
pp. 1148-1156 ◽  
Author(s):  
M. H. Laughlin ◽  
J. W. Burns ◽  
F. M. Loxsom
Keyword(s):  
Blood Flow ◽  
Regional Blood Flow ◽  
Aortic Pressure ◽  
Aortic Blood Flow ◽  
Miniature Swine ◽  
Blood Flows ◽  
Aortic Blood ◽  
High Acceleration ◽  
Regional Blood Flows ◽  
Aortic Blood Pressure

The use of the radiolabeled microsphere technique for the study of the effects of +GZ acceleration on regional blood flow is examined. A theoretical analysis of the limits of this technique in a high acceleration environment is presented. Chronically implanted, electromagnetic, aortic flow probes were used to determine the relationship between aortic blood flow velocity and +GZ acceleration in conscious adult miniature swine. It was found that conscious straining adult miniature swine, with the assistance of an inflated anti-G suit, are able to compensate quite well to acceleration levels less than or equal to +7 GZ. Exposure to +9 GZ often resulted in unstable cardiovascular states involving relative bradycardia, often progressing to asystole, declining aortic blood pressure, and markedly diminished cardiac outputs approaching zero. It was found that, if aortic pressure and heart rate attain a relatively steady state during acceleration, and if heart level mean aortic pressure is greater than or equal to 100 Torr, the application of the microsphere technique during +GZ acceleration is theoretically valid. This hypothesis was tested using the microsphere technique (9.0 +/- 0.8 microns diam) in conscious miniature swine during exposure to +GZ acceleration. It is concluded that within the defined limits the radiolabeled microsphere technique is as accurate for use during acceleration studies as it is for use in routine laboratory studies.

Age-related changes in regional blood flow in the rat

1985 ◽  
Vol 249 (3) ◽  
pp. H485-H491 ◽  
Author(s):  
R. F. Tuma ◽  
G. L. Irion ◽  
U. S. Vasthare ◽  
L. A. Heinel
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Cardiac Index ◽  
Regional Blood Flow ◽  
Adult Rats ◽  
Blood Flows ◽  
Arterial Blood ◽  
Anesthetized Rats ◽  
Regional Blood Flows ◽  
Central Hemodynamic

The purpose of this investigation was to characterize the changes in regional blood flow and central hemodynamic measures that occur in the rat as a result of the aging process. The isotope-labeled microsphere technique was used to measure cardiac output and regional blood flows in conscious and anesthetized adult (12 mo) and senescent (24 mo) Fischer 344 virgin female rats. No significant changes were observed in central hemodynamic measurements or regional blood flows in conscious rats with the exception of a 25% reduction in splenic blood flow. Pentobarbital anesthesia significantly reduced cardiac index and heart rate but elevated total peripheral resistance and mean arterial blood pressure. There was a decrease in blood flow to skeletal muscle, spleen, duodenum, stomach, and brain tissue samples and increased hepatic arterial blood flow in both age groups. The use of anesthesia caused a greater reduction in the cardiac index and brain blood flow in the senescent anesthetized rats than in the adult rats. Heart and kidney blood flows were decreased by anesthesia in the senescent rats but not in the adult rats. Skeletal muscle blood flow, however, was significantly greater in the senescent anesthetized rats than in the younger anesthetized animals. Although body weight and organ weights of the liver, spleen, kidneys, stomach, heart, and brain were significantly greater for the senescent rats, no differences could be demonstrated in tibial length or lean body mass.

scholarly journals Changes in regional blood flow and pCO2 gradients during isolated abdominal aortic blood flow reduction

2003 ◽  
Vol 29 (12) ◽  
pp. 2255-2265 ◽  
Author(s):  
Rafael Knuesel ◽  
Stephan M. Jakob ◽  
Lukas Brander ◽  
Hendrik Bracht ◽  
Andreas Siegenthaler ◽  
...  
Keyword(s):  
Blood Flow ◽  
Regional Blood Flow ◽  
Aortic Blood Flow ◽  
Flow Reduction ◽  
Aortic Blood ◽  
Blood Flow Reduction ◽  
Abdominal Aortic

Changes in regional blood flow distribution and oxygen supply during hypoxia in conscious rats

1993 ◽  
Vol 74 (1) ◽  
pp. 211-214 ◽  
Author(s):  
I. Kuwahira ◽  
N. C. Gonzalez ◽  
N. Heisler ◽  
J. Piiper
Keyword(s):  
Blood Flow ◽  
Oxygen Supply ◽  
Regional Blood Flow ◽  
Acute Hypoxia ◽  
Peripheral Resistance ◽  
Respiratory Muscles ◽  
Flow Distribution ◽  
Aortic Blood Flow ◽  
Aortic Blood ◽  
O2 Concentration

The effects of acute hypoxia on central hemodynamics, regional blood flow, and regional oxygen supply (blood flow x arterial O2 concentration) were studied in conscious resting rats. Regional blood flow was determined by the radiolabeled microsphere technique. Blood pressure, heart rate; and aortic blood flow increased and total peripheral resistance decreased significantly during hypoxia. Blood flow to brain, respiratory muscles, and liver increased both in absolute value and as a fraction of the aortic blood flow. Fractional blood flow to the gastrointestinal tract, spleen, pancreas, skin, fat, and hindlimb bones decreased during hypoxia; blood flow decreased in absolute values only in stomach and fat. Oxygen supply to brain, respiratory muscles, and liver increased during hypoxia, whereas it decreased in the remaining organs investigated.

High correlation of fractals for regional blood flows among resting and exercising skeletal muscles

1995 ◽  
Vol 269 (1) ◽  
pp. H7-H13 ◽  
Author(s):  
P. O. Iversen ◽  
G. Nicolaysen
Keyword(s):  
Blood Flow ◽  
Skeletal Muscles ◽  
Regional Blood Flow ◽  
Fractal Dimensions ◽  
Strongly Correlated ◽  
Blood Flows ◽  
Exercise Hyperemia ◽  
Regional Blood Flows ◽  
Resting Muscle ◽  
Surprising Finding

The regional blood flow distributions within single skeletal muscles are markedly uneven both at rest and during exercise hyperemia. Fractals adequately describe this perfusion heterogeneity in the resting lateral head of the gastrocnemius muscle as well as in the myocardium. Recently, we provided evidence that the fractal dimension for the blood flow distributions in this resting muscle was strongly correlated with that of the myocardium in the same rabbit. Prompted by this hitherto unknown observation, we have now examined 1) whether fractals also describe perfusion distributions within muscles with a varying metabolic activity, and 2) whether the fractal dimensions for blood flow distributions to these muscles were correlated. We used pentobarbital-anesthetized rabbits and cats. The regional distributions of blood flow within various skeletal muscles were estimated by microsphere trapping. The data unequivocally showed that the perfusion distributions could be described with fractals both in resting and in exercising muscle in both species, the corresponding fractal dimensions ranging from 1.36 to 1.41. The fractal dimensions were markedly correlated (r2 ranged from 0.82 to 0.88) when both various resting and resting plus exercising muscles were compared in the same animal. This surprising finding of high correlations for the fractal dimensions among various muscles within one animal provides a novel characteristic of blood flow heterogeneity.

Corpuscles of Stannius and blood flow regulation in freshwater North American eels, Anguilla rostrata LeSueur

1995 ◽  
Vol 145 (1) ◽  
pp. 181-194 ◽  
Author(s):  
D G Butler ◽  
G Y Oudit
Keyword(s):  
Blood Flow ◽  
Venous Blood ◽  
Systemic Resistance ◽  
Aortic Blood Flow ◽  
Venous Blood Flow ◽  
Corpuscles Of Stannius ◽  
Blood Flows ◽  
Electrolyte Disturbances ◽  
Aortic Blood ◽  
Freshwater Eels

Abstract Cardiac output (CO), heart rate (HR), stroke volume (SV), dorsal aortic blood flow (DABF), dorsal aortic blood pressure (PDA) and plasma electrolytes were monitored in stanniectomized and sham-operated freshwater eels over a 3-week period; branchial shunting and systemic resistance (RSYS) were estimated. DABF was significantly reduced by 45% from 11·72±0·48 (control) to 6·55±0·41 (n=6; day 21) ml.min−1.kg−1 within 3 weeks after the removal of the corpuscles of Stannius. This large reduction in blood flow was due to a 25% decrease in CO and a 100% increase in estimated branchial shunting which preceded the fall in CO. CO was decreased from 16·07 ±0·31 (control) to 11·91 ±1 (n=6; day 21) ml.min−1.kg−1 through a reduction in SV; there was no significant change in HR. Estimated branchial shunting, a relative measure of branchial arterio-venous blood flow, corresponded to 2·53±0·18 ml.min−1.kg−1 (control; n=12), which represents 16% of baseline CO. Ventral and dorsal aortic pulse flows also decreased following stanniectomy. The decrease in DABF occurred in conjunction with a reduction in PDA which was measured for 12 days in a separate group of eels. Baseline PDA (3·03 ±0·1 kPa) significantly decreased by 15% to 2·55 ±0·13 kPa 4 days after stanniectomy. However, this fall in PDA was transient and accompanied by an elevation in derived RSYS. These results support the hypothesis that the corpuscles of Stannius are closely linked to cardiovascular regulation in freshwater eels. Electrolyte changes (hypercalcemia, hypomagnesia, hyperkalemia and hyponatremia) were temporally coupled to the changes in blood flows. Impaired cardiovascular function and altered patterns of blood flow to osmoregulatory organs such as the gills, kidney and skin may have led to some or all of the electrolyte disturbances which followed stanniectomy. Journal of Endocrinology (1995) 145, 181–194

Fever and regional blood flows in wethers and parturient ewes

1988 ◽  
Vol 65 (1) ◽  
pp. 165-172 ◽  
Author(s):  
C. M. Blatteis ◽  
J. R. Hales ◽  
A. A. Fawcett ◽  
T. A. Mashburn
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Regional Blood Flow ◽  
Flow Distribution ◽  
Full Term ◽  
Blood Flows ◽  
Pregnant Sheep ◽  
Regional Blood Flows ◽  
Placental Blood ◽  
Placental Blood Flow

To determine whether the reported absence of fever in full-term-pregnant ewes might be associated with shifts of regional blood flows from thermogenic tissues to placenta during this critical period, fevers were induced twice by injections of Escherichia coli lipopolysaccharide (LPS, 0.25 microgram/kg iv) into each of six Merino ewes from 8 to 1 days prepartum, and their regional blood flow distribution was measured with radioactive, 15-microns-diam microspheres before and during the rise in fever (when their rectal temperature had risen approximately 0.4 degree C). Unexpectedly, fever always developed, rising to heights not significantly different at any time before parturition [4-8 days prepartum = 0.81 +/- 0.23 degree C (SE); 1-3 days prepartum = 0.75 +/- 0.17 degree C) and similar to those in three wethers treated similarly (0.90 +/- 0.10 degree C). Generally, during rising fever, blood flow in the ewes shifted away from heat loss tissues (e.g., skin, nose) to heat production tissues (e.g., shivering muscle, fat) and cardiac output increased; blood flow through redistribution organs (e.g., splanchnic bed) decreased. The reverse occurred during defervescence. Utero-placental blood flow remained high in the febrile ewes. These regional blood flow distributions during febrigenesis and lysis are essentially the same as those during exposures to ambient cold and heat, respectively. Some differences in the responses of cardiac output and its redistribution, however, were apparent between wethers and pregnant ewes. We conclude that 1) the previously reported "absence of fever in the full-term-pregnant sheep" should not be regarded as a general phenomenon and 2) full-term-pregnant sheep support fever production without sacrificing placental blood flow.

Redistribution of Regional Blood Flow after Administration of Saralasin in Salt-Depleted Dogs

1978 ◽  
Vol 55 (s4) ◽  
pp. 243s-246s
Author(s):  
Chang-Seng Liang ◽  
Haralambos Gavras ◽  
H. R. Brunner
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Regional Blood Flow ◽  
Partial Agonist ◽  
Left Ventricular ◽  
Control Group ◽  
Arterial Blood ◽  
Aortic Blood ◽  
Salt Depletion ◽  
Aortic Blood Pressure

1. Salt depletion was produced in five dogs by a low salt diet and daily administration of frusemide for 5 days; a control group of five dogs was placed on the same diet, to which 2·5 g of sodium chloride was added. 2. Saralasin infusion (0·5 μg min−1 kg−1) reduced mean aortic blood pressure and total peripheral vascular resistance and increased cardiac output in salt-depleted dogs, but did not affect the heart rate and left ventricular dP/dt. 3. Saralasin infusion increased mean aortic blood pressure slightly in normal dogs; other systemic haemodynamic parameters did not change significantly. 4. Saralasin decreased hepatic arterial flow in both normal and salt-depleted dogs, but increased blood flow to left ventricle and kidneys only in salt-depleted dogs. 5. These results suggest that saralasin exerts a partial agonist effect in normal dogs to increase arterial blood pressure, but causes a depressor response during salt depletion because it reverses the vasoconstrictor effect of angiotensin II, particularly on the renal and coronary circulations.

Microheterogeneity of myocardial blood flow in rabbit hearts during normoxic and hypoxic states

1996 ◽  
Vol 270 (2) ◽  
pp. H435-H441 ◽  
Author(s):  
T. Matsumoto ◽  
M. Goto ◽  
H. Tachibana ◽  
Y. Ogasawara ◽  
K. Tsujioka ◽  
...  
Keyword(s):  
Blood Flow ◽  
Left Ventricle ◽  
Myocardial Blood Flow ◽  
Regional Blood Flow ◽  
Blood Flows ◽  
Regional Blood Flows ◽  
Novel Method ◽  
Blood Flow Patterns ◽  
Hypoxic State ◽  
Blood Flow Heterogeneity

The goal of this study was to evaluate microheterogeneity of myocardial blood flow and its dependence on arterial O2 tension (PaO2). We measured within-layer distribution of regional blood flows in the left ventricles of anesthetized rabbits in both normoxic and hypoxic states with myocardial region sizes in the range of 0.01-1.0 mm2. A novel method of digital radiography combined with the technique of 3H-labeled desmethylimipramine deposition enabled us to visualize and accurately quantitate regional blood flow at such high levels of resolution. To analyze myocardial blood flow patterns, we computed the coefficient of variation (CV) and the correlation between adjacent regional flows (CA). The CA values were larger in the hypoxic state (PaO2 = 26 +/- 5 mmHg) than in the normoxic state (PaO2 = 97 +/- 20 mmHg) at all levels of resolution (P < 0.001). In the normoxic state, there was a transmural difference in CA (P < 0.001); CA increased with depth of the left ventricle (from subepicardium to subendocardium). However, the relation between CA and the depth of the left ventricle was not statistically significant in the hypoxic state. The CV values were smaller in the hypoxic state than in the normoxic state at all levels of resolution (P < 0.001). When the degree of resolution was reduced from 0.01 to 1.0 mm2, CV decreased by 75% in the normoxic and by 69% in the hypoxic state. Thus we conclude that 1) the decrease in PaO2 increases similarity of blood flows in nearby regions and decreases myocardial blood flow heterogeneity, and 2) similarity of regional blood flows increases with depth of the left ventricle in the normoxic state, but this transmural difference disappears in the hypoxic state.

THE EFFECT OF A CHRONIC CATHETERIZATION PROCEDURE ON REGIONAL BLOOD FLOW AND CARDIO-PULMONARY PARAMETERS IN THE LABORATORY RAT

1986 ◽  
Vol 66 (2) ◽  
pp. 553-557
Author(s):  
D. D. KITTS ◽  
S. J. YEE ◽  
A. L. SCHAEFER
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Key Words ◽  
Regional Blood Flow ◽  
Blood Gases ◽  
Blood Collection ◽  
Blood Flows ◽  
Regional Blood Flows ◽  
Anaesthetized Rat ◽  
Catheterization Procedure

A blood collection technique for conscious, catheterized, unrestrained rats was standardized. Regional blood flows to the heart, brain and viscera were significantly lower in the anaesthetized rat and followed the decline observed in cardiac output. A recovery of all measured physiological parameters to stable levels required approximately 20 min. Key words: Chronically catheterized rats, anaesthesia, blood gases, regional blood flow

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