COMPARISON BETWEEN SEASONAL AND THERMAL ACCLIMATION IN WHITE RATS: V. METABOLIC AND CARDIOVASCULAR RESPONSE TO NORADRENALINE

1961 ◽  
Vol 39 (12) ◽  
pp. 1829-1836 ◽  
Author(s):  
O. Héroux
Keyword(s):  
Blood Pressure ◽  
Oxygen Consumption ◽  
Intramuscular Injection ◽  
Cold Resistance ◽  
Cardiovascular Response ◽  
Great Sensitivity ◽  
Slight Degree ◽  
White Rats ◽  
Winter Conditions ◽  
Indoor And Outdoor

White rats cold-acclimated at a constant temperature in the laboratory are known to be more sensitive to noradrenaline than warm-acclimated controls. The present study reveals that this responsiveness to noradrenaline is linearly related to the temperature at which the animals are conditioned. Concomitant measurements (after intramuscular injection of noradrenaline) of oxygen consumption, blood pressure, and heart rates on white rats acclimatized to outdoor summer or winter conditions revealed a much greater metabolic and cardiovascular sensitivity to noradrenaline in winter than in summer rats. The slight degree of shivering upon exposure to 6 °C which was observed in the outdoor winter rats, as well as their great sensitivity to noradrenaline, suggests that under both indoor and outdoor environmental conditions, increased cold resistance is obtained through similar metabolic mechanisms.

COMPARISON BETWEEN SEASONAL AND THERMAL ACCLIMATION IN WHITE RATS: III. STUDIES OF THE ADRENAL CORTEX

1959 ◽  
Vol 37 (1) ◽  
pp. 1255-1261 ◽  
Author(s):  
O. Héroux ◽  
E. Schönbaum
Keyword(s):  
Adrenal Glands ◽  
Cold Resistance ◽  
Adrenal Weight ◽  
Similar Degree ◽  
Zona Fasciculata ◽  
Steroid Production ◽  
White Rats ◽  
Number Of Cells ◽  
Indoor And Outdoor

The rate of production of corticosteroids in vitro as well as the histological picture of the adrenal glands was studied in white rats exposed to cold for 3 months, either indoors at 6 °C in individual cages or outdoors during the winter in groups of 10.Under the indoor cold conditions, the adrenals hypertrophied within 1 week and their weight then remained constant for the following 11 weeks. The hypertrophy was due to an increase in the number of cells in the zona fasciculata. Relative to adrenal weight, the production of corticosteroids in vitro was less in the 6 °C rats than in the 30 °C controls. Under the outdoor cold conditions, the adrenal weight as well as the number of fasciculata cells remained normal, but the steroid production "in vitro" was greater than in the "summer controls". Since both "indoor" and "outdoor" cold-exposed rats have been shown previously to develop a similar degree of cold resistance as well as a similar capacity for elevating their metabolism through a non-shivering heat production mechanism, it appears that similar degrees of adaptation to cold can exist with different requirements of adrenocortical hormones.

THE EFFECT OF INTERMITTENT INDOOR COLD EXPOSURE ON WHITE RATS

1960 ◽  
Vol 38 (6) ◽  
pp. 517-521 ◽  
Author(s):  
O. Héroux
Keyword(s):  
Constant Temperature ◽  
Cold Exposure ◽  
Cold Resistance ◽  
Muscle Growth ◽  
Cold Temperature ◽  
Continuous Exposure ◽  
White Rats ◽  
Winter Conditions ◽  
The One ◽  
Cellular Alterations

Recently it has been shown that when white rats are kept in individual cages and exposed indoors to constant cold temperature or when they are exposed in groups to the outdoor winter conditions, they develop similar degrees of cold resistance and similar metabolic adjustments but they differ in endocrine, insulative, and peripheral adjustments.In an attempt to determine whether variations in temperature alone could be responsible for the type of adjustments developed outdoors, white rats were kept at 30 °C for 4 weeks but exposed to 6 °C for a few hours every day. Through these intermittent cold exposures, the animals developed the same type of acclimation as the one produced indoors by continuous exposure to a constant temperature, but to a lesser degree. Adrenals tended to hypertrophy, body and muscle growth tended to decrease, and over-all insulation appeared to decrease. In contrast to continuously exposed rats, however, they showed no cold injury, no change in ear vascularization, and no thickening of the ear epidermis, probably because the skin was never cooled long enough at any given time for the cold temperature to produce cellular alterations that could not be corrected during the warm periods.

THE CALORIGENIC RESPONSE OF COLD-ACCLIMATED WHITE RATS TO INFUSED NORADRENALINE

1960 ◽  
Vol 38 (1) ◽  
pp. 107-114 ◽  
Author(s):  
Florent Depocas
Keyword(s):  
Oxygen Consumption ◽  
Time Course ◽  
Cold Resistance ◽  
Striated Muscle ◽  
Metabolic Response ◽  
Maximal Increase ◽  
Resistance Increase ◽  
White Rats ◽  
Major Alteration ◽  
Shivering Thermogenesis

The increase in oxygen consumption during continuous intravenous injection of various doses of L-noradrenaline was measured in anesthetized rats fully acclimated to 6 °C. The metabolic response was found to be linearly related to the logarithm of the amount of noradrenaline infused per minute. The calorigenic response to infusion of noradrenaline at a level of 1 μg per minute was then measured in rats undergoing acclimation to cold. The calorigenic response was found to increase with time of exposure to the cold environment, thus paralleling previous observations in the time course of gain in cold resistance, increase in food consumption, and loss of dependence on shivering during acclimation of white rats to cold. Also, the same maximal increase in oxygen consumption was obtained on infusion of noradrenaline into functionally eviscerated and sham-operated cold-acclimated rats, thus indicating that the liver and other abdominal viscera (kidneys excluded) are not involved in the calorigenic response to noradrenaline. It is proposed, as a working hypothesis, that striated muscle is the site of the major alteration in sensitivity to noradrenaline induced by acclimation to cold. Difficulties associated with consideration of striated muscle as the source of non-shivering thermogenesis in the cold-acclimated rat are discussed.

THE EFFECT OF INTERMITTENT INDOOR COLD EXPOSURE ON WHITE RATS

1960 ◽  
Vol 38 (1) ◽  
pp. 517-521 ◽  
Author(s):  
O. Héroux
Keyword(s):  
Constant Temperature ◽  
Cold Exposure ◽  
Cold Resistance ◽  
Muscle Growth ◽  
Cold Temperature ◽  
Continuous Exposure ◽  
White Rats ◽  
Winter Conditions ◽  
The One ◽  
Cellular Alterations

Recently it has been shown that when white rats are kept in individual cages and exposed indoors to constant cold temperature or when they are exposed in groups to the outdoor winter conditions, they develop similar degrees of cold resistance and similar metabolic adjustments but they differ in endocrine, insulative, and peripheral adjustments.In an attempt to determine whether variations in temperature alone could be responsible for the type of adjustments developed outdoors, white rats were kept at 30 °C for 4 weeks but exposed to 6 °C for a few hours every day. Through these intermittent cold exposures, the animals developed the same type of acclimation as the one produced indoors by continuous exposure to a constant temperature, but to a lesser degree. Adrenals tended to hypertrophy, body and muscle growth tended to decrease, and over-all insulation appeared to decrease. In contrast to continuously exposed rats, however, they showed no cold injury, no change in ear vascularization, and no thickening of the ear epidermis, probably because the skin was never cooled long enough at any given time for the cold temperature to produce cellular alterations that could not be corrected during the warm periods.

THE CALORIGENIC RESPONSE OF COLD-ACCLIMATED WHITE RATS TO INFUSED NORADRENALINE

1960 ◽  
Vol 38 (2) ◽  
pp. 107-114 ◽  
Author(s):  
Florent Depocas
Keyword(s):  
Oxygen Consumption ◽  
Time Course ◽  
Cold Resistance ◽  
Striated Muscle ◽  
Metabolic Response ◽  
Maximal Increase ◽  
Resistance Increase ◽  
White Rats ◽  
Major Alteration ◽  
Shivering Thermogenesis

The increase in oxygen consumption during continuous intravenous injection of various doses of L-noradrenaline was measured in anesthetized rats fully acclimated to 6 °C. The metabolic response was found to be linearly related to the logarithm of the amount of noradrenaline infused per minute. The calorigenic response to infusion of noradrenaline at a level of 1 μg per minute was then measured in rats undergoing acclimation to cold. The calorigenic response was found to increase with time of exposure to the cold environment, thus paralleling previous observations in the time course of gain in cold resistance, increase in food consumption, and loss of dependence on shivering during acclimation of white rats to cold. Also, the same maximal increase in oxygen consumption was obtained on infusion of noradrenaline into functionally eviscerated and sham-operated cold-acclimated rats, thus indicating that the liver and other abdominal viscera (kidneys excluded) are not involved in the calorigenic response to noradrenaline. It is proposed, as a working hypothesis, that striated muscle is the site of the major alteration in sensitivity to noradrenaline induced by acclimation to cold. Difficulties associated with consideration of striated muscle as the source of non-shivering thermogenesis in the cold-acclimated rat are discussed.

Cardiovascular response to graded exercise in the sympathectomized-vagotomized dog

1963 ◽  
Vol 204 (2) ◽  
pp. 291-296 ◽  
Author(s):  
Edmundo Ashkar ◽  
William F. Hamilton
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Cardiac Output ◽  
Oxygen Consumption ◽  
Mean Arterial Pressure ◽  
Stroke Volume ◽  
Cardiovascular Response ◽  
Peripheral Resistance ◽  
Graded Exercise ◽  
Oxygen Difference

Seven dogs who ran well on a motor-driven treadmill were completely sympathectomized (including adrenal denervation) and subjected to unilateral vagotomy below the recurrent laryngeal branch. After recovery and retraining, a terminal experiment was performed in which, after completing the vagotomy, direct Fick determinations of cardiac output and continuous recordings of mean arterial pressure, heart rate, and oxygen consumption were made at rest and during increasing exercise The results were compared with those described by Barger et al. ( Am. J. Physiol. 184: 613, 1956) for normal dogs running at smaller speeds and grades. The heart rate of the operated dogs increased from 117 to 134. Barger's normal dogs doubled their heart rate. The A-V oxygen difference increased with work slightly less than Barger's normal dogs but the scatter in both groups was wide, as was the case with the stroke volume. The resting cardiac output was nearly normal in the operated dogs but increased only 34% with exercise, as against 200–300% in Barger's normals. Oxygen consumption increased about twofold as against the expected normal of three- to sevenfold. Peripheral resistance in both groups went down about 40%. The blood pressure in the normal increased substantially while that in the operated dogs fell about 20% to an average of 60 mm Hg.

COMPARISON BETWEEN SEASONAL AND THERMAL ACCLIMATION IN WHITE RATS: III. STUDIES OF THE ADRENAL CORTEX

1959 ◽  
Vol 37 (11) ◽  
pp. 1255-1261 ◽  
Author(s):  
O. Héroux ◽  
E. Schönbaum
Keyword(s):  
Adrenal Glands ◽  
Cold Resistance ◽  
Adrenal Weight ◽  
Similar Degree ◽  
Zona Fasciculata ◽  
Steroid Production ◽  
White Rats ◽  
Number Of Cells ◽  
Indoor And Outdoor

The rate of production of corticosteroids in vitro as well as the histological picture of the adrenal glands was studied in white rats exposed to cold for 3 months, either indoors at 6 °C in individual cages or outdoors during the winter in groups of 10.Under the indoor cold conditions, the adrenals hypertrophied within 1 week and their weight then remained constant for the following 11 weeks. The hypertrophy was due to an increase in the number of cells in the zona fasciculata. Relative to adrenal weight, the production of corticosteroids in vitro was less in the 6 °C rats than in the 30 °C controls. Under the outdoor cold conditions, the adrenal weight as well as the number of fasciculata cells remained normal, but the steroid production "in vitro" was greater than in the "summer controls". Since both "indoor" and "outdoor" cold-exposed rats have been shown previously to develop a similar degree of cold resistance as well as a similar capacity for elevating their metabolism through a non-shivering heat production mechanism, it appears that similar degrees of adaptation to cold can exist with different requirements of adrenocortical hormones.

scholarly journals Impact of Standing Speed on the Peripheral and Central Hemodynamic Response to Orthostasis

Hypertension ◽  
2020 ◽  
Vol 75 (2) ◽  
pp. 524-531 ◽  
Author(s):  
John D. O’Connor ◽  
Matthew D. L. O’Connell ◽  
Hugh Nolan ◽  
Louise Newman ◽  
Silvin P. Knight ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Cerebral Oxygenation ◽  
Cardiovascular Response ◽  
Adult Population ◽  
Early Period ◽  
Standing Position ◽  
Transition Time ◽  
Statistical Adjustment ◽  
Central Hemodynamic

Assessment of the cerebrovascular and cardiovascular response to standing has prognostic value for a range of outcomes in the older adult population. Studies generally attempt to control for standing speed differences by asking participants to stand in a specified time but little is known about the range of transition times observed. This study aimed to characterize how standing speed associates with cardiovascular and cerebrovascular measures following transition from supine to standing. Continuous cerebral oxygenation, heart rate, systolic and diastolic blood pressure were monitored for 3 minutes after transitioning from supine to standing. An algorithm was used to calculate the time taken to transition from existing Finometer data (from the height correction unit). Linear mixed-effects models were used to assess the influence of transition time on each of the signals while adjusting for covariates. Transition time ranged from 2 to 27 s with 17% of participants taking >10 s to stand. Faster transition was associated with a more extreme decrease 10 s after standing but improved recovery at 20 s for cerebral oxygenation and blood pressure. Standing faster was associated with an elevated heart rate on initiation of stand and a quicker recovery 10 to 20 s after standing. The speed of transitioning from supine to standing position is associated with cardiovascular and cerebrovascular response in the early period after standing (<40 s). Care should be taken in the interpretation of findings which may be confounded by standing speed and statistical adjustment for standing time should be applied where appropriate.

Effects of nicotine on canine intestinal blood flow and oxygen consumption

1984 ◽  
Vol 246 (2) ◽  
pp. G195-G203
Author(s):  
R. H. Gallavan ◽  
Y. Tsuchiya ◽  
E. D. Jacobson
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Oxygen Consumption ◽  
Muscle Tension ◽  
Intestinal Blood Flow ◽  
Mesenteric Blood Flow ◽  
State Response ◽  
Arterial Blood ◽  
Intestinal Circulation

The purpose of this study was to determine the effects of nicotine on intestinal blood flow and oxygen consumption. The intravenous infusion of nicotine at doses corresponding to those experienced by smokers produced a transient increase in systemic arterial blood pressure and mesenteric blood flow. Subsequently a steady-state response developed that consisted of a reduction in mesenteric blood flow due to both a decrease in blood pressure and an increase in intestinal vascular resistance. This increase in resistance was probably due to increased levels of circulating catecholamines. The intra-arterial infusion of nicotine into the intestinal circulation at doses experienced by the average smoker had no effect on either intestinal blood flow or oxygen consumption. Similarly, under in vitro conditions nicotine had no direct effect on intestinal vascular smooth muscle tension. Thus, nicotine appears to reduce intestinal blood flow indirectly as a result of its systemic effects.

Abstract 119: Influence of Anesthetics on the Hemodynamic Response in a Rat Model of Hemorrhagic Shock

Circulation ◽  
2019 ◽  
Vol 140 (Suppl_2) ◽  
Author(s):  
Claudius Balzer ◽  
Franz J Baudenbacher ◽  
Susan S Eagle ◽  
Michele M Salzman ◽  
William J Cleveland ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Hemorrhagic Shock ◽  
Rat Model ◽  
Cardiovascular Response ◽  
Femoral Vein ◽  
Blood Pressure Measurement ◽  
Experimental Models ◽  
Sprague Dawley ◽  
Compensatory Mechanisms ◽  
Arterial Blood

Introduction: Experimental models of hemorrhagic shock (HS) in rats are important to test new treatments that may improve outcomes in humans, and general anesthesia is required during these experiments. The volatile anesthetic Isoflurane is known for its beneficial effects in rat HS models. Focusing on cardiovascular compensatory mechanisms, we wanted to evaluate Isoflurane versus the injectable anesthetic Pentobarbital in our rat model of mild HS (class 2). We hypothesize that Isoflurane during development of HS improves hemodynamics compared to Pentobarbital. Methods: Twelve Sprague-Dawley rats were initially anesthetized with an intraperitoneal (IP) injection of Pentobarbital (45 mg/kg) and intubated (1 L/min, FiO 2 0.25); heart rate (HR) was monitored by subcutaneous ECG needles. Femoral artery and vein were cannulated for continuous blood pressure measurement and delivery of fluids, respectively. In one group (n=7), anesthesia was continued with repeated IP injections of Pentobarbital (dose mg/kg), the other group (n=5) received continuous Isoflurane (1%). After 30 min of stabilization and administration of Heparin (100 IU/kg), HS was induced by removal of 1 ml of blood over 1 min via the femoral vein, repeated every 3 min until a volume of 5 ml of blood was removed. Mean arterial blood pressure (MAP) and HR were recorded and analyzed in LabChart. Results: During baseline, rats showed no significant differences in HR and MAP between both groups. After 5 ml of hemorrhage, both groups showed significant changes compared to baseline, with significantly higher MAP and HR in rats given only Pentobarbital. Conclusions: In our rat model of HS, Isoflurane dampens the physiologic response to compensate for mild hemorrhage. The cardiovascular response of rats in the Isoflurane group was a decrease of HR and MAP to every ml of hemorrhage, while rats given only Pentobarbital were able to maintain their MAP by raising their HR until decompensation.

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