Heart rate and oxygen uptake response to angiotensin in the squirrel monkey at 10 degrees C

1977 ◽  
Vol 233 (1) ◽  
pp. H10-H14
Author(s):  
N. Wasserstrum ◽  
J. A. Herd
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Intravenous Infusion ◽  
Squirrel Monkeys ◽  
Arterial Blood ◽  
Baroreceptor Stimulation ◽  
The Central Nervous System ◽  
Total Body ◽  
Total Body Oxygen ◽  
Oxygen Uptake Response

Unanesthetized squirrel monkeys exposed to an ambient temperature of 10 degrees C showed elevations in total body oxygen consumption (VO2), systemic arterial blood pressure (BP), and heart rate (hr) above values recorded at 28 degrees C. Further elevation of BP in the cold by intravenous infusion of phenylephrine (5-50 microgram/kg-min) was accompanied by reduction in both VO2 and HR, and the changes in VO2 were proportional to those in HR. When BP was raised by intravenous infusion of angiotensin (0.05-1.0 microgram/kg-min), large elevations in BP were again accompanied by reductions in HR and VO2. However, for equivalent elevations in BP, the depressions in both HR and VO2 were much smaller with angiotensin than they were with phenylephrine. Previous studies in this laboratory have demonstrated that in response to experimental elevation of BP, reflexes originating at the sinoaortic baroreceptors depress not only HR but also VO2. The present results suggest that angiotensin modulates baro-reflexive responses to elevation in BP. The reductions in HR and VO2 that ordinarily occur in response to baroreceptor stimulation may be modified by an action of angiotensin on the central nervous system.

Baroreflexive depression of oxygen consumption in the squirrel monkey at 10 degrees C

1977 ◽  
Vol 232 (5) ◽  
pp. H451-H458 ◽  
Author(s):  
N. Wasserstrum ◽  
J. A. Herd
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Oxygen Consumption ◽  
Rectal Temperature ◽  
Cold Exposure ◽  
Squirrel Monkeys ◽  
Inhibitory Effects ◽  
Arterial Blood ◽  
Total Body ◽  
Total Body Oxygen

Unanesthetized squirrel monkeys exposed to an ambient temperature of 10 degrees C showed elevations in total body oxygen consumption (VO2), arterial blood pressure (BP), and heart rate (HR) above values recorded at 28 degrees C. Further elevation of BP in the cold by intravenous infusion of phenylephrine was accompanied by immediate reduction in VO2, inhibition of shivering, and decrease in rectal temperature, as well as immediate reduction in HR. The magnitude of reduction in VO2 correlated with the magnitude of the concomitant baroreflexive bradycardia. When the pressor effects of phenylephrine were opposed by administration of diazoxide or phentolamine, the inhibitory effects of phenylephrine on both HR and VO2 were abolished. In animals previously subjected to bilateral sinoaortic denervation, both the bradycardia and depression in oxygen consumption normally associated with BP elevation were markedly reduced. These results suggest that elevation of blood pressuere can inhibit the thermoregulatory increase in total body oxygen consumption normally produced by cold exposure, and that this inhibition, like the concomitant bradycardia, is probably mediated via the sinoaortic baroreceptors.

Adrenergic, respiratory, and cardiovascular effects of core cooling in humans

1997 ◽  
Vol 272 (2) ◽  
pp. R557-R562 ◽  
Author(s):  
S. M. Frank ◽  
M. S. Higgins ◽  
L. A. Fleisher ◽  
J. V. Sitzmann ◽  
H. Raff ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Oxygen Consumption ◽  
Arterial Blood Pressure ◽  
Intravenous Infusion ◽  
Cardiovascular Responses ◽  
Arterial Blood ◽  
Norepinephrine Concentration ◽  
Total Body ◽  
Core Cooling ◽  
Total Body Oxygen

The adrenergic, respiratory, and cardiovascular responses to isolated core cooling were assessed in awake human subjects. Mild core hypothermia was induced by intravenous infusion of 30 or 40 ml/kg of cold saline (4 degrees C) on 2 separate days. A warm intravenous infusion (30 ml/kg, 37 degrees C) was given on a third day as a control treatment. Mean norepinephrine concentration increased 400% and total body oxygen consumption increased 30% when core temperature decreased 0.7 degrees C. Mean norepinephrine concentration increased 700% and total body oxygen consumption increased 112% when core temperature decreased 1.3 degrees C. Core cooling was associated with peripheral vasoconstriction and increased mean arterial blood pressure, whereas heart rate was unchanged. Plasma epinephrine and cortisol concentrations were unchanged during core cooling. There were no changes in any measured parameter with the warm infusion. These findings suggest that mild hypothermia induced by isolated core cooling is associated with an adrenergic response characterized by peripheral sympathetic nervous system activation without a significant adrenocortical or adrenomedullary response. The respiratory and cardiovascular responses to core cooling are characterized by a shivering-induced increase in metabolic rate, norepinephrine-mediated peripheral vasoconstriction, and increased arterial blood pressure.

Elevation of arterial blood pressure in the squirrel monkey at 10 degrees C

1977 ◽  
Vol 232 (5) ◽  
pp. H459-H463
Author(s):  
N. Wasserstrum ◽  
J. A. Herd
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Oxygen Consumption ◽  
Arterial Blood Pressure ◽  
Mean Arterial Blood Pressure ◽  
Skeletal Muscles ◽  
Ambient Temperatures ◽  
Arterial Blood ◽  
Total Body ◽  
Total Body Oxygen

Systemic arterial blood pressure, heart rate, and total body oxygen consumption were measured in seven unanesthetized squirrel monkeys exposed to ambient temperatures of 28 degrees C and 10 degrees C. At 28 degrees C, subjects sat quietly, the average mean arterial blood pressure was 116 +/- 16 (mean +/- SD, n - 7) mmHg, heart rate was 274 +/- 31 beats/min, and oxygen consumption was 14 +/- 1.4 ml/kg-min. At 10 degrees C, the animals shivered vigorously, the average mean arterial blood pressure was 139 +/- 16 mmHg, heart rate was 328 +/- 18 beats/min, and oxygen consumption was 31.6 +/- 3.9 ml/kg-min. Thus, the oxygen consumption more than doubled, the blood pressure rose by approximately 21%, and the heart rate by approximately 20%. Elevations in heart rate as well as systemic mean arterial blood pressure during exposure to low ambient temperature were probably mediated by sympathetic-adrenal discharges as well as by activity of skeletal muscles.

Cardioaccelerator action of angiotensin

1962 ◽  
Vol 202 (2) ◽  
pp. 237-240 ◽  
Author(s):  
S. D. Nishith ◽  
L. D. Davis ◽  
W. B. Youmans
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Angiotensin Ii ◽  
Arterial Pressure ◽  
Abdominal Aorta ◽  
Intravenous Infusion ◽  
Control Level ◽  
Arterial Blood ◽  
Initial Decrease ◽  
Slow Intravenous Infusion

Effects of synthetic angiotensin II on heart rate and blood pressure were determined in dogs under the influence of morphine (3 mg/kg) and chloralose (90 mg/kg). Angiotensin in total doses of 2.5–20 µg, rapidly injected intravenously in intact dogs, caused an initial decrease in heart rate followed by a rise above the control level, despite the continued elevation of arterial blood pressure. When the degree of rise in arterial pressure was buffered by a mechanical compensator connected with the abdominal aorta, rapid intravenous angiotensin injection produced no initial cardioinhibitory phase, and the magnitude of the accleration of heart rate was much greater than in the unbuffered animal. Slow intravenous infusion of angiotensin in some cases caused only a rise in heart rate. In sinoaortic denervated animals both blood pressure and heart rate were greatly increased when a total dose of 10 µg angiotensin was rapidly injected intravenously. Thus, it is demonstrated that the cardioinhibitory response to angiotensin depends largely or exclusively on reflex effects from sinoaortic pressoreceptors, and that angiotensin has a strong cardioaccelerator action which is exerted through the efferent nerves to the heart.

Depressed ventilatory response to hypoxia in hypothermic newborn piglets: role of glutamate

1998 ◽  
Vol 84 (3) ◽  
pp. 830-836 ◽  
Author(s):  
Annette McCormick ◽  
Cleide Suguihara ◽  
Jian Huang ◽  
Carlos Devia ◽  
Dorothy Hehre ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Arterial Blood Pressure ◽  
Nucleus Tractus Solitarius ◽  
Ventilatory Response ◽  
Blood Gases ◽  
Arterial Blood ◽  
Significant Linear Correlation ◽  
The Central Nervous System ◽  
Ventilatory Response To Hypoxia

To evaluate whether changes in extracellular glutamate (Glu) levels in the central nervous system could explain the depressed hypoxic ventilatory response in hypothermic neonates, 12 anesthetized, paralyzed, and mechanically ventilated piglets <7 days old were studied. The Glu levels in the nucleus tractus solitarius obtained by microdialysis, minute phrenic output (MPO), O2 consumption, arterial blood pressure, heart rate, and arterial blood gases were measured in room air and during 15 min of isocapnic hypoxia (inspired O2 fraction = 0.10) at brain temperatures of 39.0 ± 0.5°C [normothermia (NT)] and 35.0 ± 0.5°C [hypothermia (HT)]. During NT, MPO increased significantly during hypoxia and remained above baseline. However, during HT, there was a marked decrease in MPO during hypoxia (NT vs. HT, P < 0.03). Glu levels increased significantly in hypoxia during NT; however, this increase was eliminated during HT ( P < 0.02). A significant linear correlation was observed between the changes in MPO and Glu levels during hypoxia ( r = 0.61, P < 0.0001). Changes in pH, arterial[Formula: see text], O2 consumption, arterial blood pressure, and heart rate during hypoxia were not different between the NT and HT groups. These results suggest that the depressed ventilatory response to hypoxia observed during HT is centrally mediated and in part related to a decrease in Glu concentration in the nucleus tractus solitarius.

Hypoxia-induced metabolic and core temperature changes in the squirrel monkey

1977 ◽  
Vol 42 (2) ◽  
pp. 273-278 ◽  
Author(s):  
D. H. Horstman ◽  
L. E. Banderet
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Core Temperature ◽  
Heat Production ◽  
Squirrel Monkeys ◽  
Experimental Conditions ◽  
Temperature Changes ◽  
Arterial Blood ◽  
Arterial Ph ◽  
Skin Temperatures

To identify components of reduced core temperature (Tre) with exposure to hypoxia, oxygen uptake (VO2) and skin temperatures were measured in chair-restrained squirrel monkeys during conditions of 21% O2, 11% O2, and 11% O2 + 5% CO2. Exposure to 11% O2 resulted in a 20% decrease in VO2 and a 1.8 degrees C reduction of Tre with skin temperatures closely paralleling Tre. The addition of 5% CO2 to 11% O2 effectively blocked the decrease of both VO2 and Tre. The responses of one monkey (LD) exhibiting decreased Tre (greater than 2.0 degrees C) and 20% decrease in VO2 were compared to those of another (SD) exhibiting decreased Tre (less than 0.5 degrees C) and little change of VO2 under the same experimental conditions. Increased mean arterial blood pressure (BPa) and heart rate (HR) occurred for monkey SD, while for monkey LD BPa decreased and HR increased slightly. Arterial pressure of oxygen (PaO2) and calculated arterial saturation of oxygen (SaO2) were higher, while PaCO2 was lower for monkey SD than for monkey LD. When 5% CO2 was added to 11% O2 both animals exhibited decreased PaO2, little change of Tre, VO2, PaCO2, arterial pH, and calculated SaO2, and increased BPa and HR. These data suggest that decreased Tre resulted from reduced heat production and reduced oxygen transport was primarily responsible for reduction of heat production.

Ontogeny of baroreflex control of renal sympathetic nerve activity and heart rate

1992 ◽  
Vol 263 (6) ◽  
pp. H1819-H1826 ◽  
Author(s):  
J. L. Segar ◽  
G. Hajduczok ◽  
B. A. Smith ◽  
D. C. Merrill ◽  
J. E. Robillard
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Arterial Blood Pressure ◽  
Sympathetic Nerve Activity ◽  
Nerve Activity ◽  
Renal Sympathetic Nerve Activity ◽  
Arterial Blood ◽  
Baroreflex Function ◽  
Baroreceptor Stimulation ◽  
Renal Sympathetic

The purpose of this study was to characterize the developmental changes in baroreflex function during fetal and postnatal life in sheep. Resting mean arterial blood pressure increased significantly from 55 +/- 2 mmHg in fetuses to 86 +/- 3 mmHg in newborn lambs and to 105 +/- 4 mmHg in 4- to 6-wk-old lambs. The sensitivity (gain) of the renal sympathetic nerve activity (RSNA) response to baroreceptor stimulation was greater (P < 0.05) in fetuses (-7.7 +/- 1.9%/mmHg) than in newborn (-2.9 +/- 0.1%/mmHg) and 4- to 6-wk-old lambs (-2.2 +/- 0.2%/mmHg). The threshold and saturation pressures for the baroreflex function curve were lower (P < 0.05) in fetuses (44 +/- 2 and 61 +/- 2 mmHg) than in newborn (59 +/- 4 and 106 +/- 5 mmHg) or 4- to 6-wk-old lambs (78 +/- 5 and 132 +/- 6 mmHg). Similar findings were observed when the heart rate response to baroreceptor stimulation was examined. Additional experiments were performed in newborn and 4- to 6-wk-old lambs to determine whether the rise in arterial blood pressure associated with postnatal maturation contributed to baroreflex resetting. Sustained elevation of arterial blood pressure by 15–20 mmHg for over 90 min did not reset the baroreflex function curve in either newborn or 4- to 6-wk-old lambs.(ABSTRACT TRUNCATED AT 250 WORDS)

Compression Stocking Length Effects on Arterial Blood Pressure and Heart Rate Following Head-Up Tilt in Healthy Volunteers

2014 ◽  
Vol 63 (6) ◽  
pp. 435-438 ◽  
Author(s):  
Kunihiko Tanaka ◽  
Shiori Tokumiya ◽  
Yumiko Ishihara ◽  
Yumiko Kohira ◽  
Tetsuro Katafuchi
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Healthy Volunteers ◽  
Arterial Blood Pressure ◽  
Compression Stocking ◽  
Arterial Blood ◽  
Head Up Tilt ◽  
Length Effects
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