Renal and systemic hemodynamic responses to sustained submaximal exertion in horses

1990 ◽  
Vol 258 (5) ◽  
pp. R1177-R1183 ◽  
Author(s):  
K. W. Hinchcliff ◽  
K. H. McKeever ◽  
L. M. Schmall ◽  
C. W. Kohn ◽  
W. W. Muir
Keyword(s):  
Heart Rate ◽  
Blood Flow ◽  
Cardiac Output ◽  
Total Solid ◽  
Systemic Hemodynamics ◽  
Solid Concentration ◽  
Maximum Heart Rate ◽  
Filtration Fraction ◽  
Systemic Hemodynamic ◽  
Heart Rates

We investigated the effects of 1 h of sustained submaximal exertion on the renal and systemic hemodynamics of six horses. The horses ran on a treadmill at a speed that produced heart rates of 55-60% of each horse's maximum heart rate. Exertion produced heart rates of 121 +/- 6.6 and 126 +/- 6.1 (SE) beats/min after 15 and 60 min, respectively. Cardiac output increased significantly (P less than 0.05) from 70.1 +/- 3.1 to 246.2 +/- 4.7 ml.min-1.kg body wt-1 after 15 min of exertion and thereafter did not change. There was no significant change from rest in p-aminohippuric acid and creatinine clearances, filtration fraction, or renal blood flow during exertion. Plasma total solid concentration and hematocrit increased by 3.8 and 8.6%, respectively, between 20 and 60 min of exertion. Pulmonary artery temperature increased significantly from 37.6 degrees C at rest to 38.6 degrees C at 60 min of exertion. This study demonstrates the ability of the horse to maintain renal hemodynamics similar to resting values and systemic hemodynamics at steady-state values despite hemoconcentration and increased body temperature during sustained submaximal exertion.

Diastolic pressure and peripheral resistance during stellate ganglion stimulation

1963 ◽  
Vol 204 (1) ◽  
pp. 71-72 ◽  
Author(s):  
Edward D. Freis ◽  
Jay N. Cohn ◽  
Thomas E. Liptak ◽  
Aristide G. B. Kovach
Keyword(s):  
Heart Rate ◽  
Blood Flow ◽  
Cardiac Output ◽  
Total Peripheral Resistance ◽  
Diastolic Pressure ◽  
Stellate Ganglion ◽  
Peripheral Resistance ◽  
Resistance Vessels ◽  
Left Stellate Ganglion ◽  
Increased Blood Flow

The mechanism of the diastolic pressure elevation occurring during left stellate ganglion stimulation was investigated. The cardiac output rose considerably, the heart rate remained essentially unchanged, and the total peripheral resistance fell moderately. The diastolic rise appeared to be due to increased blood flow rather than to any active changes in resistance vessels.

Cardiac output in muscular exercise at 5,800 m (19,000 ft)

1964 ◽  
Vol 19 (3) ◽  
pp. 441-447 ◽  
Author(s):  
L. G. C. E. Pugh
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Sea Level ◽  
Indirect Evidence ◽  
Mean Value ◽  
Muscular Exercise ◽  
Maximum Output ◽  
Work Intensity ◽  
Maximum Heart Rate ◽  
Sea Level Pressure

Cardiac output during muscular exercise was estimated by the acetylene technique on four members of the Himalayan Scientific and Mountaineering expedition 1960–1961 at sea level and 5,800 m (19,000 ft). The output for a given work intensity at 5,800 m (19,000 ft) was comparable with the output at the same work intensity at sea level, but the maximum output was reduced, the mean value being 16 liters/min, compared with 23 liters/min at sea level. Heart rates during light and moderate exercise were higher than the rates observed at the same work intensity at sea level. The maximum heart rate during exercise was limited to 130–150 beats/min compared with 180–196 beats/min at sea level. The stroke volume at altitude was lower than at sea level at each work rate. On breathing oxygen at sea-level pressure, heart rate for a given work intensity was reduced; but the maximum heart rate increased. Indirect evidence suggested that maximum cardiac output increased but probably not to the sea-level values because of the increased hemoglobin and lower heart rate. altitude acclimatization; cardiac function, work and altitude; hypoxia and cardiac output Submitted on July 29, 1963

scholarly journals Development of a Simple ImageJ-Based Method for Dynamic Blood Flow Tracking in Zebrafish Embryos and Its Application in Drug Toxicity Evaluation

Inventions ◽  
2019 ◽  
Vol 4 (4) ◽  
pp. 65 ◽  
Author(s):  
Fiorency Santoso ◽  
Bonifasius Putera Sampurna ◽  
Yu-Heng Lai ◽  
Sung-Tzu Liang ◽  
Erwei Hao ◽  
...  
Keyword(s):  
Heart Rate ◽  
Blood Flow ◽  
Cardiac Output ◽  
Blood Cell ◽  
Stroke Volume ◽  
Flow Velocity ◽  
Blood Flow Velocity ◽  
Video Recording ◽  
Cardiovascular Function ◽  
Zebrafish Embryos

This study aimed to develop a simple and cost-effective method to measure blood flow in zebrafish by using an image-based approach. Three days post fertilization (dpf) zebrafish embryos were mounted with methylcellulose and subjected to video recording for tracking blood flow under an inverted microscope equipped with a high-speed CCD camera. In addition, Hoffman lens was used to enhance the blood cell contrast. The red blood cell movement was tracked by using the TrackMate plug-in in the ImageJ image processing program. Moreover, Stack Difference and Time Series Analyzer plug-in were used to detect dynamic pixel changes over time to calculate the blood flow rate. In addition to blood flow velocity and heart rate, the effect of drug treatments on other cardiovascular function parameters, such as stroke volume and cardiac output remains to be explored. Therefore, by using this method, the potential side effects on the cardiovascular performance of ethyl 3-aminobenzoate methanesulfonate (MS222) and 3-isobutyl-1-methylxanthine (IBMX) were evaluated. MS222 is a common anesthetic, while IBMX is a naturally occurring methylxanthine. Compared to normal embryos, MS222- and IBMX-treated embryos had a reduced blood flow velocity by approximately 72% and 58%, respectively. This study showed that MS222 significantly decreased the heart rate, whereas IBMX increased the heart rate. Moreover, it also demonstrated that MS222 treatment reduced 50% of the stroke volume and cardiac output. While IBMX decreased the stroke volume only. The results are in line with previous studies that used expensive instruments and complicated software analysis to assess cardiovascular function. In conclusion, a simple and low-cost method can be used to study blood flow in zebrafish embryos for compound screening. Furthermore, it could provide a precise measurement of clinically relevant cardiac functions, specifically heart rate, stroke volume, and cardiac output.

Lingual, splanchnic, and systemic hemodynamic and carbon dioxide tension changes during endotoxic shock and resuscitation

2005 ◽  
Vol 98 (1) ◽  
pp. 108-113 ◽  
Author(s):  
Jorge A. Guzman ◽  
Mathew S. Dikin ◽  
James A. Kruse
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Endotoxic Shock ◽  
Mucosal Blood Flow ◽  
Canine Model ◽  
Endotoxin Shock ◽  
Carbon Dioxide Tension ◽  
Systemic Hemodynamic ◽  
Hemodynamic Variables ◽  
Blood Flow Patterns

Sublingual and intestinal mucosal blood flow and Pco2 were studied in a canine model of endotoxin-induced circulatory shock and resuscitation. Sublingual Pco2 (PsCO2) was measured by using a novel fluorescent optrode-based technique and compared with lingual measurements obtained by using a Stowe-Severinghaus electrode [lingual Pco2 (PlCO2)]. Endotoxin caused parallel changes in cardiac output, and in portal, intestinal mucosal, and sublingual blood flow (Q̇s). Different blood flow patterns were observed during resuscitation: intestinal mucosal blood flow returned to near baseline levels postfluid resuscitation and decreased by 21% after vasopressor resuscitation, whereas Q̇s rose to twice that of the preshock level and was maintained throughout the resuscitation period. Electrochemical and fluorescent Pco2 measurements showed similar changes throughout the experiments. The shock-induced increases in PsCO2 and PlCO2 were nearly reversed after fluid resuscitation, despite persistent systemic arterial hypotension. Vasopressor administration induced a rebound of PsCO2 and PlCO2 to shock levels, despite higher cardiac output and Q̇s, possibly due to blood flow redistribution and shunting. Changes in PlCO2 and PsCO2 paralleled gastric and intestinal Pco2 changes during shock but not during resuscitation. We found that the lingual, splanchnic, and systemic circulations follow a similar pattern of blood flow variations in response to endotoxin shock, although discrepancies were observed during resuscitation. Restoration of systemic, splanchnic, and lingual perfusion can be accompanied by persistent tissue hypercarbia, mainly lingual and intestinal, more so when a vasopressor agent is used to normalize systemic hemodynamic variables.

Pulsatile Flow Characteristics in a Stenotic Aortic Valve Model: An In Vitro Experimental Study

2019 ◽  
Author(s):  
Ruihang Zhang ◽  
Yan Zhang
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Aortic Valve ◽  
Pulsatile Flow ◽  
Heart Diseases ◽  
Flow Characteristics ◽  
Aortic Valve Area ◽  
Heart Rates ◽  
Valvular Heart Diseases

Abstract Aortic stenosis (AS) is one of the most common valvular heart diseases around the globe. The accurate assessment of AS severity is important and strongly associated with accurate interpretation of the hemodynamic parameters across the stenotic valve. In this study, we conducted in vitro fluid dynamic experiments to investigate the pulsatile flow characteristics of a stenotic aortic valve as a function of heart rate. An in vitro cardiovascular flow simulator was used to generate pulsatile flow with a prescribed waveform (40% systolic period and 4L/min cardiac output) under varied heart rates (50 bpm, 75 bpm and 100 bpm). The stenotic valve was constructed by molding silicone into three-leaflet aortic valve geometries wrapping around thin fabrics which increases its stiffness and tensile strength. Two-dimensional phase-locked particle image velocimetry (PIV) was employed to quantify the flow field characteristics of the stenotic valve. Pressure waveforms were recorded to evaluate the severity of the stenosis via the Gorlin and Hakki equations. Results suggest that as the heart rate increases, the peak pressure gradient across the stenotic aortic valve increases significantly under the same cardiac output. Analysis also shows the estimated aortic valve area (AVA) decreases as the heart rate increases under the same cardiac output using Gorlin equation estimation, while the trend is reversed using Hakki equation estimation. Under phase-locked conditions, quantitative flow characteristics, such as phase-averaged flow velocity, turbulence kinetic energy (TKE) for the stenotic aortic valve were analyzed based on the PIV data. Results suggest that the peak systolic jet velocity downstream of the valve increases as the heart rate increases, implying a longer pressure recovery distance as heart rate increases. While the turbulence at peak systole is higher under the slower heart rate, the faster heart rate contributes to a higher turbulence during the late systole and early diastole phases. Based on the comparison with no-valve cases, the differences in TKE was mainly related to the dynamics of leaflets under different heart rates. Overall, the results obtained in this study demonstrate that the hemodynamics of a stenotic aortic valve is complex and the assessment of AS could be significantly affected by the pulsating rate of the flow.

Effect of heart rate on myocardial blood flow in dogs with left ventricular hypertrophy

1980 ◽  
Vol 239 (5) ◽  
pp. H621-H627
Author(s):  
T. R. Vrobel ◽  
W. S. Ring ◽  
R. W. Anderson ◽  
R. W. Emery ◽  
R. J. Bache
Keyword(s):  
Heart Rate ◽  
Blood Flow ◽  
Left Ventricular Hypertrophy ◽  
Myocardial Blood Flow ◽  
Ventricular Hypertrophy ◽  
Lateral Wall ◽  
Left Ventricular ◽  
Myocardial Mass ◽  
Previous Suggestion ◽  
Heart Rates

Because of the previous suggestion that subendocardial perfusion may be inadequate in the hypertrophied heart, this study was carried out to examine the response of transmural myocardial blood flow to pacing induced tachycardia in dogs with chronic left ventricular hypertrophy. Myocardial hypertrophy, produced by banding the ascending aorta of puppies at 5-6 wk of age, resulted in an 87% average increase in relative left ventricular mass compared with the control dogs. Myocardial blood flow was examined during ventricular pacing at heart rates of 100, 200, and 250 beats/min using radionuclide-labeled microspheres. Mean blood flow per unit myocardial mass was similar in the two groups of dogs at a heart rate of 100 beats/min and increased regularly during pacing in both groups of animals. Increasing heart rates did not change the transmural pattern of myocardial blood flow in the normal dogs, but in the animals with left ventricular hypertrophy pacing at 250 beats/min resulted in a significant redistribution of perfusion away from the subendocardium, with the ratio of subendocardial/subepicardial blood flow falling from 1.03 +/- 0.08 at 100 beats/min to 0.83 +/0 0.06 at 250 beats/min (P < 0.01). This redistribution of blood flow away from the subendocardium was especially marked in the regions encompassing the papillary muscles and the intervening left ventricular lateral wall.

Orthostatic intolerance after spaceflight

1996 ◽  
Vol 81 (1) ◽  
pp. 7-18 ◽  
Author(s):  
J. C. Buckey ◽  
L. D. Lane ◽  
B. D. Levine ◽  
D. E. Watenpaugh ◽  
S. J. Wright ◽  
...  
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Stroke Volume ◽  
Space Shuttle ◽  
Orthostatic Intolerance ◽  
Peripheral Resistance ◽  
Systemic Hemodynamic ◽  
Vasoconstrictor Response ◽  
Before And After ◽  
Underlying Mechanisms

Orthostatic intolerance occurs commonly after spaceflight, and important aspects of the underlying mechanisms remain unclear. We studied 14 individuals supine and standing before and after three space shuttle missions of 9-14 days. After spaceflight, 9 of the 14 (64%) crew members could not complete a 10-min stand test that all completed preflight. Pre- and postflight supine hemodynamics were similar in both groups except for slightly higher systolic and mean arterial pressures preflight in the finishers [15 +/- 3.7 and 8 +/- 1.2 (SE) mmHg, respectively; P < 0.05]. Postflight, finishers and nonfinishers had equally large postural reductions in stroke volume (-47 +/- 3.7 and -48 +/- 3.3 ml, respectively) and increases in heart rate (35 +/- 6.6 and 51 +/- 5.2 beats/min, respectively). Cardiac output during standing was also similar (3.6 +/- 0.4 and 4.1 +/- 0.3 l/min, respectively). However, the finishers had a greater postflight vasoconstrictor response with higher total peripheral resistance during standing (22.3 +/- 1.2 units preflight and 29.4 +/- 2.3 units postflight) than did the nonfinishers (20.1 +/- 1.1 units preflight and 19.9 +/- 1.4 units postflight). We conclude that 1) the primary systemic hemodynamic event, i.e., the postural decrease in stroke volume, was similar in finishers and nonfinishers and 2) the heart rate response and cardiac output during standing were not significantly different, but 3) the postural vasoconstrictor response was significantly greater among the finishers (P < 0.01).

Cardiovascular and Sympatho-Adrenal Responses to Mental Stress in Primary Hypertension

1993 ◽  
Vol 85 (4) ◽  
pp. 401-409 ◽  
Author(s):  
Madeleine Lindqvist ◽  
Thomas Kahan ◽  
Anders Melcher ◽  
Paul Hjemdahl
Keyword(s):  
Heart Rate ◽  
Blood Flow ◽  
Cardiac Output ◽  
Neuropeptide Y ◽  
Mental Stress ◽  
Forearm Blood Flow ◽  
Primary Hypertension ◽  
Hypertensive Patients ◽  
Control Subjects ◽  
Venous Plasma

1. Eleven untreated men with mild to moderate primary hypertension and 10 normotensive control subjects were studied at rest and during a mental stress test (Stroop colour word conflict test), which has previously been used in studies of hypertensive patients with regard to non-invasive cardiovascular variables and venous plasma catecholamine concentrations. 2. Heart rate, central cardiovascular pressures, cardiac output (thermodilution) and forearm blood flow (strain gauge plethysmography) were determined. Systemic and forearm vascular resistances were calculated. Arterial and venous plasma adrenaline and noradrenaline concentrations were measured by h.p.l.c., and arterial noradrenaline spillover and noradrenaline overflow from the forearm were assessed by isotope methodology ([3H]noradrenaline). Neuropeptide Y-like immunoreactivity was measured by radioimmunoassay. 3. In hypertensive patients heart rate, arterial blood pressure, cardiac output and forearm blood flow increased by 28%, 13%, 37% and 115%, respectively, and forearm and systemic vascular resistances decreased by 48% and 21%, respectively (P <0.001 for all responses), during stress. These responses were not different from those of the control group. 4. Arterial noradrenaline spillover rose by 63% and noradrenaline overflow from the forearm rose by 150% in the hypertensive patients in response to mental stress (P <0.001); no significant group differences could be demonstrated. However, the forearm noradrenaline overflow response to stress tended to be greater in the hypertensive group (P = 0.11). Arterial adrenaline concentrations doubled in both groups (P <0.001). 5. Arterial neuropeptide Y-like immunoreactivity increased slightly and similarly in the two groups (+7% in hypertensive patients and +9% in control subjects, P <0.05 for both) in response to mental stress. No net overflow of neuropeptide-Y-like immunoreactivity could be detected over the forearm. 6. It is concluded that the cardiovascular and sympatho-adrenal responses to mental stress evaluated in this study are similar in hypertensive patients and control subjects. Stress-induced vasodilatation occurs in the forearm despite signs of increased local sympathetic activity, indicating that powerful neurohormonal vasodilator mechanisms are activated by mental stress.

scholarly journals Changes in regional blood volume and blood flow during static handgrip

2007 ◽  
Vol 292 (1) ◽  
pp. H215-H223 ◽  
Author(s):  
Julian M. Stewart ◽  
Leslie D. Montgomery ◽  
June L. Glover ◽  
Marvin S. Medow
Keyword(s):  
Heart Rate ◽  
Blood Flow ◽  
Cardiac Output ◽  
Blood Volume ◽  
Cardiac Contractility ◽  
Peripheral Resistance ◽  
Low Frequencies ◽  
Exercise Pressor Reflex ◽  
Heart Rate Regulation ◽  
Pressor Reflex

Increased blood pressure (BP) and heart rate during exercise characterizes the exercise pressor reflex. When evoked by static handgrip, mechanoreceptors and metaboreceptors produce regional changes in blood volume and blood flow, which are incompletely characterized in humans. We studied 16 healthy subjects aged 20–27 yr using segmental impedance plethysmography validated against dye dilution and venous occlusion plethysmography to noninvasively measure changes in regional blood volumes and blood flows. Static handgrip while in supine position was performed for 2 min without postexercise ischemia. Measurements of heart rate and BP variability and coherence analyses were used to examine baroreflex-mediated autonomic effects. During handgrip exercise, systolic BP increased from 120 ± 10 to 148 ± 14 mmHg, whereas heart rate increased from 60 ± 8 to 82 ± 12 beats/min. Heart rate variability decreased, whereas BP variability increased, and transfer function amplitude was reduced from 18 ± 2 to 8 ± 2 ms/mmHg at low frequencies of ∼0.1 Hz. This was associated with marked reduction of coherence between BP and heart rate (from 0.76 ± 0.10 to 0.26 ± 0.05) indicative of uncoupling of heart rate regulation by the baroreflex. Cardiac output increased by ∼18% with a 4.5% increase in central blood volume and an 8.5% increase in total peripheral resistance, suggesting increased cardiac preload and contractility. Splanchnic blood volume decreased reciprocally with smaller decreases in pelvic and leg volumes, increased splanchnic, pelvic and calf peripheral resistance, and evidence for splanchnic venoconstriction. We conclude that the exercise pressor reflex is associated with reduced baroreflex cardiovagal regulation and driven by increased cardiac output related to enhanced preload, cardiac contractility, and splanchnic blood mobilization.

Leg crossing with muscle tensing, a physical counter-manoeuvre to prevent syncope, enhances leg blood flow

2007 ◽  
Vol 112 (3) ◽  
pp. 193-201 ◽  
Author(s):  
Jan T. Groothuis ◽  
Nynke van Dijk ◽  
Walter ter Woerds ◽  
Wouter Wieling ◽  
Maria T. E. Hopman
Keyword(s):  
Heart Rate ◽  
Blood Flow ◽  
Cardiac Output ◽  
Stroke Volume ◽  
Orthostatic Intolerance ◽  
Peripheral Resistance ◽  
Haemodynamic Effects ◽  
Vascular Conductance ◽  
Leg Blood Flow ◽  
Head Up Tilt

In patients with orthostatic intolerance, the mechanisms to maintain BP (blood pressure) fail. A physical counter-manoeuvre to postpone or even prevent orthostatic intolerance in these patients is leg crossing combined with muscle tensing. Although the central haemodynamic effects of physical counter-manoeuvres are well documented, not much is known about the peripheral haemodynamic events. Therefore the purpose of the present study was to examine the peripheral haemodynamic effects of leg crossing combined with muscle tensing during 70° head-up tilt. Healthy subjects (n=13) were monitored for 10 min in the supine position followed by 10 min in 70° head-up tilt and, finally, for 2 min of leg crossing with muscle tensing in 70° head-up tilt. MAP (mean arterial BP), heart rate, stroke volume, cardiac output and total peripheral resistance were measured continuously by Portapres. Leg blood flow was measured using Doppler ultrasound. Leg vascular conductance was calculated as leg blood flow/MAP. A significant increase in MAP (13 mmHg), stroke volume (27%) and cardiac output (18%), a significant decrease in heart rate (−5 beats/min) and no change in total peripheral resistance during the physical counter-manoeuvre were observed when compared with baseline 70° head-up tilt. A significant increase in leg blood flow (325 ml/min) and leg vascular conductance (2.9 arbitrary units) were seen during the physical counter-manoeuvre when compared with baseline 70° head-up tilt. In conclusion, the present study indicates that the physical counter-manoeuvre of leg crossing combined with muscle tensing clearly enhances leg blood flow and, at the same time, elevates MAP.

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