Cardiac output and organ blood flow in warm- and cold-acclimated rats exposed to cold

1968 ◽  
Vol 46 (4) ◽  
pp. 653-659 ◽  
Author(s):  
L. Jansky ◽  
J. S. Hart
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Skeletal Muscles ◽  
Organ Blood Flow ◽  
Internal Organs ◽  
Exposure To Cold ◽  
Brown Adipose ◽  
Production Increase ◽  
Distribution Of Cardiac Output ◽  
Fractional Distribution

Cold acclimation increased the cardiac output of unanesthetized rats when measured at 30 °C. After exposure to 9 °C for 70 min cardiac output further increased by 46% in both warm- and cold-acclimated rats. From the changes in the fractional distribution of cardiac output after cold exposure it was shown that the blood flow increased significantly in muscular organs (heart, diaphragm, skeletal muscles) and in the adrenals of warm-acclimated rats. In cold-acclimated rats the blood flow to the brown and white adipose tissues, pancreas, kidney, intestine, liver, and other internal organs was also increased in a cold environment, and accounted for 65% of the increase in blood flow during exposure to cold compared with only 36% in warm-acclimated rats. It is estimated that the extramuscular thermogenesis can account for a greater proportion of the total nonshivering thermogenesis in cold-acclimated rats. The contribution of brown adipose tissue is estimated not to exceed about 6% of the total heat production increase in cold-acclimated rats during exposure to cold.

Comparison of microspheres and 86Rb+ as tracers of the distribution of cardiac output in rats indicates invalidity of 86Rb+-based measurements

1978 ◽  
Vol 56 (1) ◽  
pp. 97-109 ◽  
Author(s):  
David O. Foster ◽  
M. Lorraine Frydman
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Cardiac Output ◽  
Valid Measure ◽  
White Rats ◽  
Direct Measurements ◽  
Brown Adipose ◽  
Valid Data ◽  
Distribution Of Cardiac Output ◽  
Fractional Distribution

The technique of using γ-labeled plastic microspheres (15 ± 5 μm) to measure cardiac output (CO) and its fractional distribution (FD) to individual tissues and organs was judged by various criteria to give valid data when applied to barbital-sedated warm-acclimated or cold-acclimated (CA) white rats, which were either resting or responding calorigenically to infused noradrenaline (NA). The FD of CO to each of 16 tissues or organs of CA rats at rest or responding to NA was then estimated both with 86Rb+ and with microspheres, the two tracers being injected simultaneously. For only seven of the tissues examined in resting rats and only one in NA-infused rats was the FD of CO estimated with 86Rb+ not significantly different from that estimated with microspheres. 86Rb+ to microsphere ratios of the FD of CO to individual tissues ranged from 3.5 and 3.0 for liver and skeletal muscle, respectively, down to 0.09 and 0.07 for brown adipose tissue (BAT) and brain. Since microsphere-based estimates of blood flow to the interscapular BAT of CA rats responding to NA were corroborated by direct measurements of venous efflux from the tissue, it is unequivocal that the 86Rb+-based estimate of the fraction of CO directed to interscapular BAT was highly erroneous. When considered along with data from the literature, the present findings support a conclusion that the uptake of 86Rb+ by a tissue frequently does not provide a valid measure of the FD of CO to the tissue. Some of the factors that are likely responsible for this situation are discussed, and it is suggested that only by a fortuitous combination of circumstances does the uptake of 86Rb+ by a tissue sometimes match the FD of CO to the tissue.

Distribution of cardiac output during diurnal changes of activity in rats

1991 ◽  
Vol 261 (5) ◽  
pp. H1487-H1493 ◽  
Author(s):  
M. D. Delp ◽  
R. O. Manning ◽  
J. V. Bruckner ◽  
R. B. Armstrong
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Feeding Behavior ◽  
Diurnal Cycle ◽  
Skeletal Muscles ◽  
Muscle Blood Flow ◽  
Diurnal Changes ◽  
Time Periods ◽  
Distribution Of Cardiac Output ◽  
Total Muscle

Rat locomotor and feeding behavior varies on a diurnal basis; at night the animals actively forage and eat, whereas during the day they are more inactive and somnolent. At night, cardiac output is higher, presumably for enhanced perfusion of the active muscles to support increased metabolism and for enhanced perfusion of the digestive organs to support increased digestion and nutrient absorption. Conversely, it is hypothesized that during the daytime, blood flow to these two tissues is relatively low. The purpose of this study was to test these hypotheses by measuring cardiac output and the distribution of cardiac output in rats at various times in the diurnal cycle (8:00 A.M., 4:00 P.M., and 8:00 P.M.). The radiolabeled microsphere technique was used to measure cardiac output and distribution of blood flow to the tissues. Distribution of the total cardiac output was accounted for by complete dissection, weighing, and counting of organs and carcass. Cardiac output at 8:00 P.M. (136 +/- 9 ml/min) was elevated 13% (P less than 0.05) over that at 4:00 P.M. The proportion of the cardiac output distributed to the skeletal muscles (4:00 P.M.: 25%; 8:00 P.M.: 27%) and to the digestive tract (4:00 P.M.: 14%; 8:00 P.M.: 14%) did not change between the two time periods. Thus total muscle blood flow increased (P less than 0.05) from 31 +/- 2 at 4:00 P.M. to 36 +/- 4 ml/min at 8:00 P.M.; the only digestive organ to show a significant increase in blood flow from 4:00 P.M. to 8:00 P.M. was the stomach (133 +/- 17 to 166 +/- 19 ml/min, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Changes in distribution of cardiac output by surface-induced deep hypothermia in dogs

1976 ◽  
Vol 40 (6) ◽  
pp. 876-882 ◽  
Author(s):  
Y. Kawashima ◽  
K. Okada ◽  
I. Kosugi ◽  
H. In-Nami ◽  
Y. Yamaguchi
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Deep Hypothermia ◽  
Total Output ◽  
Organ Blood Flow ◽  
Relative Distribution ◽  
Low Cardiac Output ◽  
Vascular Beds ◽  
The Brain ◽  
Distribution Of Cardiac Output

The effects of surface-induced deep hypothermia on organ blood flow and on the distribution of cardiac output were investigated in the anesthetized dog. Organ flows were determined by the radioactive microsphere technique. Phenoxybenzamine (POB) was administered prior to hypothermia to minimize vasoconstriction and hence facilitate cooling. Measurements were made before POB, on stabilization after POB, and during hypothermia. Cardiac output was reduced by POB as was blood flow to the pancreas, small intestine, and skeletal muscle. Hypothermia, following POB, produced a further fall in Q and during this maneuver blood flow fell in all organs and vascular beds studied. The relative distribution of Q during hypothermia was essentially the same as in the control except the brain, kidneys, and pancreas received a smaller fraction of the total output. The relatively normal distribution of a reduced cardiac output during hypothermia was in marked contrast to distribution of comparable low cardiac output induced by hemorrhage. In the latter condition, the fraction of the cardiac output perfusing the brain, kidneys, adrenals, and hepatic artery was increased.

Organ blood flow and distribution of cardiac output in dopexamine- or dobutamine-treated endotoxemic rats

1993 ◽  
Vol 8 (2) ◽  
pp. 117-127 ◽  
Author(s):  
Antoine A. van Lambalgen ◽  
Annemieke A. van Kraats ◽  
Margot F. Mulder ◽  
Gerard C. van den Bos ◽  
Tom Teerlink ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Organ Blood Flow ◽  
Distribution Of Cardiac Output
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