scholarly journals Blood pressure and blood flow variation during postural change from sitting to standing: model development and validation

2005 ◽  
Vol 99 (4) ◽  
pp. 1523-1537 ◽  
Author(s):  
Mette S. Olufsen ◽  
Johnny T. Ottesen ◽  
Hien T. Tran ◽  
Laura M. Ellwein ◽  
Lewis A. Lipsitz ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Mathematical Model ◽  
Blood Flow ◽  
Young Subject ◽  
Venous Blood ◽  
Cardiovascular Responses ◽  
Physiological Data ◽  
Postural Change ◽  
Metabolic Demand ◽  
Arterial Blood

Short-term cardiovascular responses to postural change from sitting to standing involve complex interactions between the autonomic nervous system, which regulates blood pressure, and cerebral autoregulation, which maintains cerebral perfusion. We present a mathematical model that can predict dynamic changes in beat-to-beat arterial blood pressure and middle cerebral artery blood flow velocity during postural change from sitting to standing. Our cardiovascular model utilizes 11 compartments to describe blood pressure, blood flow, compliance, and resistance in the heart and systemic circulation. To include dynamics due to the pulsatile nature of blood pressure and blood flow, resistances in the large systemic arteries are modeled using nonlinear functions of pressure. A physiologically based submodel is used to describe effects of gravity on venous blood pooling during postural change. Two types of control mechanisms are included: 1) autonomic regulation mediated by sympathetic and parasympathetic responses, which affect heart rate, cardiac contractility, resistance, and compliance, and 2) autoregulation mediated by responses to local changes in myogenic tone, metabolic demand, and CO2 concentration, which affect cerebrovascular resistance. Finally, we formulate an inverse least-squares problem to estimate parameters and demonstrate that our mathematical model is in agreement with physiological data from a young subject during postural change from sitting to standing.

scholarly journals Cardiovascular Responses During Downhill Treadmill Walking at Self-Selected Intensity in Older Adults

2013 ◽  
Vol 21 (3) ◽  
pp. 335-347 ◽  
Author(s):  
Mandy L. Gault ◽  
Richard E. Clements ◽  
Mark E.T. Willems
Keyword(s):  
Blood Pressure ◽  
Older Adults ◽  
Peripheral Resistance ◽  
Cardiovascular Responses ◽  
Treadmill Walking ◽  
Metabolic Demand ◽  
Arterial Blood ◽  
Cardiac Strain ◽  
Downhill Walking ◽  
Future Work

Cardiovascular responses of older adults to downhill (DTW, –10% incline) and level treadmill walking (0%) at self-selected walking speed (SSWS) were examined. Fifteen participants (age 68 ± 4 yr, height 1.69 ± 0.08 m, body mass 74.7 ± 8.1 kg) completed two 15-min walks at their SSWS (4.6 ± 0.6 km/hr). Cardiovascular responses were estimated using an arterial-volume finger clamp and infrared plethysmography. Oxygen consumption was 25% lower during DTW and associated with lower values for stroke volume (9.9 ml/beat), cardiac output (1.0 L/min), arteriovenous oxygen difference (a-v O2 diff, 2.4 ml/L), and systolic blood pressure (10 mmHg), with no differences in heart rate or diastolic and mean arterial blood pressure. Total peripheral resistance (TPR) was higher (2.11 mmHg) during DTW. During downhill walking, an exercise performed with reduced cardiac strain, endothelial changes, and reduced metabolic demand may be responsible for the different responses in TPR and a-v O2 diff. Future work is warranted on whether downhill walking is suitable for higher risk populations.

Adrenal catecholamines in E. coli endotoxin shock

1961 ◽  
Vol 16 (2) ◽  
pp. 348-350 ◽  
Author(s):  
Florian Nykiel ◽  
Vincent V. Glaviano
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Arterial Blood Pressure ◽  
Venous Blood ◽  
Endotoxin Shock ◽  
Mean Blood Pressure ◽  
E Coli ◽  
Arterial Blood ◽  
Splanchnic Nerves

In dogs with left adrenal cannulation, administration of 1 mg/kg of purified E. coli endotoxin resulted in a decrease in mean blood pressure and adrenal blood flow. These changes were accompanied by significant increases in levels of epinephrine in adrenal venous blood. Release of epinephrine by the adrenals in endotoxin shock was due to a neurogenic mechanism, since sectioning of the splanchnic nerves prevented secretion of epinephrine. The rise in epinephrine output from an intact adrenal was noted to occur only in the presence of a significant decrease in arterial blood pressure; therefore endotoxin causes adrenal stimulation from reflexes initiated by the hypothalamus or peripheral baroreceptors. Submitted on September 20, 1960

Integrating behavior and cardiovascular responses: posture and locomotion. I. Static analysis

1993 ◽  
Vol 265 (6) ◽  
pp. R1458-R1468 ◽  
Author(s):  
O. A. Smith ◽  
C. A. Astley ◽  
F. A. Spelman ◽  
E. V. Golanov ◽  
V. G. Chalyan ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Blood Flow ◽  
Computer Control ◽  
Cardiovascular Responses ◽  
Papio Hamadryas ◽  
Code Generator ◽  
Frequency Distributions ◽  
Arterial Blood ◽  
Free Ranging

Heart rate, arterial blood pressure, and renal and mesenteric or femoral blood flow were telemetered from 11 Papio hamadryas in an untethered free-ranging situation. The animals' behavior was recorded on videotape, and the cardiovascular (CV) data were recorded on the audio channels of the tape. The behavior was coded, and the codes were linked to the CV data via a time-code generator and computer control. The CV data were digitized into 1-s intervals, and the static relations between CV measures and the postures/locomotions (P/Ls) associated with the behavior were analyzed. The total frequency distributions for heart rate, blood pressure, and renal conductance approximated Gaussian distributions, whereas femoral conductance was positively skewed. The distribution for renal conductance suggested that during normal waking conditions the kidney is not maximally dilated and may increase or decrease its blood flow. All distributions were highly influenced by the Sit category, which occupied 80% of the total time. The CV measures for all P/Ls had wide ranges, and the CV values associated with each P/L overlapped those for the other P/Ls. The heart rate and renal conductance associated with the various P/Ls showed the largest deviations from the grand means and therefore contributed the most to the ability to discriminate one P/L from another. Blood pressure varied little from one P/L to another. The patterns of CV variables served to distinguish particular P/Ls very effectively. The frequency distributions were separated best when they were parceled on the basis of the intensity of behavior associated with a particular P/L. These variations in intensity were the major cause of the overlaps in the frequency distributions associated with P/Ls.

Effect of intravenous infusion of adrenaline on the cardiovascular responses to distal body subatmospheric pressure in man

1988 ◽  
Vol 75 (4) ◽  
pp. 389-394 ◽  
Author(s):  
I. W. Fellows ◽  
I. A. MacDonald ◽  
T. Bennett ◽  
D. P. O'Donoghue
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Blood Flow ◽  
Arterial Blood Pressure ◽  
Forearm Blood Flow ◽  
Cardiovascular Responses ◽  
Saline Infusion ◽  
Subatmospheric Pressure ◽  
Arterial Blood ◽  
Adrenaline Infusion

1. On two separate occasions, at least 1 week apart, seven young healthy male subjects received intravenous infusions of either adrenaline [0.27 nmol (50 ng) min−1 kg−1] or saline (154 mmol/l NaCl), plus ascorbic acid (5.68 mmol/l), over 30 min. 2. On each occasion, the subjects were exposed to distal body subatmospheric pressure (DBSP), 0 to 50 mmHg (0 to 6.65 kPa) in 10 mmHg (1.33 kPa) steps, before infusion, during the final 15 min of the infusion, and at 15 min and 30 min after the cessation of the infusion. 3. Venous adrenaline concentrations of 2.85 ±0.22 nmol/l were achieved during the adrenaline infusion, compared with 0.49 ± 0.07 nmol/l during the saline infusion (P < 0.001). At 15 min and at 30 min after cessation of the adrenaline infusion, venous adrenaline concentrations had fallen to levels similar to those achieved after the cessation of the saline infusion. 4. Heart rate rose significantly from 58 ±4 beats/min to 67 ±4 beats/min during the adrenaline infusion (P < 0.05), but there was no further significant change in response to 50 mmHg (6.65 kPa) DBSP. At 30 min after the cessation of the adrenaline infusion, heart rate rose from 60 ± 4 beats/min to 78 ± 7 beats/min in response to 50 mmHg DBSP. This increase was significantly greater than that observed before the adrenaline infusion [58 ± 4 beats/min to 69 ±7 beats/min during 50 mmHg (6.65 kPa) DBSP; P < 0.01]. 5. During the infusion of adrenaline, systolic arterial blood pressure rose and diastolic arterial blood pressure fell, but the blood pressure responses to DBSP were unaffected. 6. Forearm blood flow increased significantly during adrenaline infusion but there was no significant difference in the fall in forearm blood flow during DBSP compared with the values before infusion. At 15 min after the cessation of the adrenaline infusion, forearm vascular resistance rose proportionately more in response to DBSP than it had before the adrenaline infusion (P < 0.05). 7. These results are consistent with adrenaline-mediated facilitation of sympathetic neuronal release of noradrenaline in the heart and in the forearm vascular bed.

scholarly journals Effects of Vibration, Noise and Restraint on Heart Rate, Blood Pressure and Renal Blood Flow in the Pig

1983 ◽  
Vol 76 (10) ◽  
pp. 841-847 ◽  
Author(s):  
D B Stephens ◽  
R D Rader
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Blood Flow ◽  
Renal Blood Flow ◽  
Cardiovascular Responses ◽  
Experimental Manipulation ◽  
Farm Animals ◽  
Arterial Blood ◽  
Ultrasonic Techniques ◽  
Vibration Noise

Pigs and other farm animals are usually transported at least once during their lives; for example, all meat animals are finally taken to the abattoir for slaughter. The vibration, noise and handling associated with such transportation is usually novel to the animals, and therefore constitutes a potential ‘stressor’. Such adverse stimuli may trigger physiological and psychological changes which rapidly produce profound changes in blood flow to peripheral organs, particularly the kidney, whose blood vessels are richly supplied with sympathetic nerve fibres. In the present study, ultrasonic techniques have been used with chronically implanted flow sensors for measuring heart rate (HR) and changes in renal blood flow (RBF) in conscious, freestanding and unanaesthetized pigs to monitor their cardiovascular responses to vibration, noise and various handling procedures. In addition, arterial blood pressure (BP) was measured via a catheter placed in the carotid artery. To ensure that vibration and noise could be accurately reproduced, a transport simulator (TS) was constructed in the laboratory. A small decrease of approximately 5% was observed in RBF during the first few minutes of exposure to vibration and noise, but this returned to the control levels monitored in undisturbed animals within a few minutes. Thereafter, RBF became significantly elevated for the remaining period of exposure to vibration and noise. In contrast, HR remained significantly increased throughout. BP was not significantly changed as a result of the experimental manipulation. Restraint and handling of the animals appeared to cause maximal disturbance. HR and BP were more than doubled compared with the resting value, but there was a concomitant marked decrease in RBF. For example, in one pig, the normal renal blood flow of 5 ml/s was reduced to nearly half during the handling procedure. This, however, returned to normal levels within 4 min of release.

5. Blood pressure and blood flow

2016 ◽  
pp. 83-102
Author(s):  
Chris Cooper
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Driving Force ◽  
Beta Blockers ◽  
Venous Blood ◽  
The Body ◽  
Chronic Hypertension ◽  
Arterial Blood ◽  
Lifestyle Choices

The heart is the organ that pumps blood around the body. If the heart stops functioning, blood does not flow. The driving force for this flow is the pressure difference between the arterial blood leaving the heart and the returning venous blood. ‘Blood pressure and blood flow’ first considers how blood pressure is measured and how blood pressure can affect health. High blood pressure is called hypertension and low blood pressure hypotension. Chronic hypertension has serious long-term adverse health consequences, but can be treated with improved lifestyle choices and a range of medicines, including anti-hypertensive drugs, beta blockers, and ACE inhibitor drugs. The different molecules affecting blood flow are also considered.

scholarly journals Respiratory and cardiovascular responses of the exercising chicken to spinal cord cooling at different ambient temperatures. I. Cardiovascular responses and blood gases

1985 ◽  
Vol 114 (1) ◽  
pp. 415-426
Author(s):  
G. M. Barnas ◽  
M. Gleeson ◽  
W. Rautenberg
Keyword(s):  
Blood Pressure ◽  
Spinal Cord ◽  
Treadmill Exercise ◽  
Venous Blood ◽  
Blood Gases ◽  
Cardiovascular Responses ◽  
Mixed Venous Blood ◽  
Ambient Temperatures ◽  
Arterial Blood ◽  
Exercise Period

We measured oxygen consumption (VO2), heart rate (HR), stroke volume (SV), cardiac output (CO) and mean arterial blood pressure (MBPa) of chickens during 15 min treadmill exercise at 0.5 ms-1 and 0.8 ms-1 at thermoneutral (23 degrees C), low (9 degrees C) and high (34 degrees C) ambient temperature (Ta); the vertebral canal was cooled to 34 degrees C during the middle 5 min of each exercise period. PO2, PCO2, pH and oxygen content (CO2) of the arterial and mixed venous blood were also measured. VO2 during exercise was not significantly affected by Ta. Spinal cord cooling produced definite increases in VO2, CO and SV during 0.5 ms-1 exercise at 9 degrees C; otherwise, effects of spinal cord cooling were not significant. HR, SV and CO were all linearly related to VO2; these relationships were unaffected by spinal cord cooling or Ta. Blood pressure did not increase during exercise. PaCO2 and P-vCO2 did not increase significantly during exercise. The arterial-venous CO2 difference was increased by exercise only at 34 degrees C. The chickens generally hyperventilated at 34 degrees C Ta compared to the other Ta values. No consistent effect on blood gases or on pH and CO2 of the blood could be attributed to spinal cord cooling.

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.

scholarly journals Plasticity in breathing and arterial blood pressure following acute intermittent hypercapnic hypoxia in infant rat pups with a partial loss of 5-HT neurons

2015 ◽  
Vol 309 (10) ◽  
pp. R1273-R1284 ◽  
Author(s):  
Jennifer Magnusson ◽  
Kevin J. Cummings
Keyword(s):  
Blood Pressure ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Arterial Blood Pressure ◽  
Cardiovascular Responses ◽  
Partial Loss ◽  
Rat Pups ◽  
Arterial Blood ◽  
Hypercapnic Hypoxia ◽  
Long Term Facilitation

The role of serotonin (5-HT) neurons in cardiovascular responses to acute intermittent hypoxia (AIH) has not been studied in the neonatal period. We hypothesized that a partial loss of 5-HT neurons would reduce arterial blood pressure (BP) at rest, increase the fall in BP during hypoxia, and reduce the long-term facilitation of breathing (vLTF) and BP following AIH. We exposed 2-wk-old, 5,7-dihydroxytryptamine-treated and controls to AIH (10% O2; n = 13 control, 14 treated), acute intermittent hypercapnia (5% CO2; n = 12 and 11), or acute intermittent hypercapnic hypoxia (AIHH; 10% O2, 5% CO2; n = 15 and 17). We gave five 5-min challenges of AIH and acute intermittent hypercapnia, and twenty ∼20-s challenges of AIHH to mimic sleep apnea. Systolic BP (sBP), diastolic BP, mean arterial pressure, heart rate (HR), ventilation (V̇e), and metabolic rate (V̇o2) were continuously monitored. 5,7-Dihydroxytryptamine induced an ∼35% loss of 5-HT neurons from the medullary raphe. Compared with controls, pups deficient in 5-HT neurons had reduced resting sBP (∼6 mmHg), mean arterial pressure (∼5 mmHg), and HR (56 beats/min), and experienced a reduced drop in BP during hypoxia. AIHH induced vLTF in both groups, reflected in increased V̇e and V̇e/V̇o2, and decreased arterial Pco2. The sBP of pups deficient in 5-HT neurons, but not controls, was increased 1 h following AIHH. Our data suggest that a relatively small loss of 5-HT neurons compromises resting BP and HR, but has no influence on ventilatory plasticity induced by AIHH. AIHH may be useful for reversing cardiorespiratory defects related to partial 5-HT system dysfunction.

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