Effects of acute cold exposure on the distribution of cardiac output in the sheep

1976 ◽  
Vol 366 (2-3) ◽  
pp. 153-157 ◽  
Author(s):  
J. R. S. Hales ◽  
J. W. Bennett ◽  
A. A. Fawcett
Keyword(s):  
Cardiac Output ◽  
Cold Exposure ◽  
Acute Cold Exposure ◽  
Distribution Of Cardiac Output

GASTROINTESTINAL BLOOD FLOW DISTRIBUTION IN COLD-EXPOSED SHEEP

1980 ◽  
Vol 60 (3) ◽  
pp. 677-681 ◽  
Author(s):  
A. L. SCHAEFER ◽  
B. A. YOUNG
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Gastrointestinal Tract ◽  
Cold Exposure ◽  
Flow Distribution ◽  
Treatment Groups ◽  
Acute Cold Exposure ◽  
Control Versus ◽  
Gastrointestinal Blood Flow ◽  
Distribution Of Cardiac Output

The influence of acute and chronic cold exposure on the distribution of cardiac output to the gastrointestinal tract was measured in adult sheep (35–50 kg) using radioactive microspheres containing 141Ce and 113Sn. Groups of four sheep were exposed in controlled temperature chambers to either (1) control temperature, 18 °C for 10–12 wk; (2) acute cold, exposure to 3 °C for 12 h; (3) chronic cold, exposure to 3 °C for 10–12 wk. In the control, acute cold and chronic cold treatments, respectively, 26.4, 20.5 and 19.4% of cardiac output was distributed to the gastrointestinal tract. The estimated amount of blood flow (mL/100 g wet tissue/min) to the total gastrointestinal tract was not significantly different among the three treatment groups (67 mL/100 g/min for the control versus 62 and 50 mL/100 g/min, respectively, for the acute cold and the chronic cold sheep). However, there was a significant decrease in blood flow to the reticulo-rumen of the acute cold- and chronic cold-exposed sheep (34.0 and 37.8 mL/100 g wet tissue/min for the acute and chronic cold sheep versus 56.0 mL/100 g/min for the control sheep). The redistribution of gastrointestinal blood flow induced by exposure to cold may be a factor in reduced nutrient absorption in cold-exposed ruminants.

DISTRIBUTION OF BLOOD FLOW IN COLD STRESSED PIGLETS

1979 ◽  
Vol 59 (4) ◽  
pp. 721-726 ◽  
Author(s):  
P. E. V. WILLIAMS ◽  
R. O. PARKER ◽  
B. A. YOUNG ◽  
F. X. AHERNE
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Cold Stress ◽  
Rectal Temperature ◽  
Cold Exposure ◽  
Alimentary Tract ◽  
Distribution Of Cardiac Output

Radioactive ruthenium labelled microspheres 15 ± 3 μm in diameter were used to determine distribution of cardiac output in unfed control (35 °C) and unfed cold stressed (5 °C) piglets 3.5 h of age. The cold stress produced an average 7.1 °C drop in rectal temperature and a redistribution of blood flow. In cold exposed piglets the adrenal fraction of cardiac output was significantly (P < 0.05) lower: 0.56% in the control compared with 0.29% in the cold exposed piglets; however, the relative blood flow to the adrenals was higher than for other tissues. The fractions of cardiac output reaching the psoas and biceps muscles increased (P < 0.05) by 148 and 260%, respectively, during cold exposure, while that reaching the heart, brain, alimentary tract, skin and fat was not significantly (P > 0.05) affected by cold exposure.

Tolerance of estrogen-treated rats to acute cold exposure

1979 ◽  
Vol 47 (1) ◽  
pp. 59-66 ◽  
Author(s):  
M. J. Fregly ◽  
D. L. Kelleher ◽  
D. J. Black
Keyword(s):  
Oxygen Consumption ◽  
Cold Exposure ◽  
Previous Experiment ◽  
Female Rats ◽  
Control Group ◽  
Maximal Rate ◽  
Acute Cold Exposure ◽  
Exposure To Cold ◽  
Rate Of Oxygen Consumption ◽  
Rate Of Cooling

Female rats treated chronically with ethynylestradiol (36 micrograms/kg per day) alone, and in combination with the progestational agent, norethynodrel (253 micrograms/kg per day), cooled significantly faster than controls when lightly restrained and exposed to air at 5 degrees C. Rate of cooling of rats given only norethynodrel was similar to that of the control group. In other studies, rate of oxygen consumption was determined for all groups during acute exposure to cold (14 degrees C). All estrogen-treated groups achieved the same maximal rate of oxygen consumption as control and norethynodrel-treated groups during cold exposure, but cooled significantly faster. Two groups of female rats were treated chronically with ethynylestradiol at two separate doses (36 and 61 micrograms/kg per day). An untreated group served as controls. Rate of oxygen consumption of all animals were measured during restraint and exposure to cold (18 degrees C). The estrogen-treated groups again achieved the same maximal rate of oxygen consumption as the control group, but also cooled significantly faster despite the fact that the cold stress was less severe than in the previous experiment. That estrogen-treated rats cooled faster than controls in both studies despite achieving a maximal rate of heat production which did not differ from controls suggests that reduced cold tolerance of estrogen-treated rats may be related to increased heat loss.

Sign in / Sign up

Export Citation Format

Share Document