scholarly journals Effects of preload and afterload on the performance of the in situ perfused portal heart of the New Zealand hagfish Eptatretus cirrhatus

1996 ◽  
Vol 199 (2) ◽  
pp. 401-405 ◽  
Author(s):  
M Johnsson ◽  
M Axelsson ◽  
W Davison ◽  
M Forster ◽  
S Nilsson
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
New Zealand ◽  
Stroke Volume ◽  
Power Output ◽  
Chronotropic Response ◽  
Beta Adrenoceptor ◽  
Output Pressure ◽  
Adrenoceptor Antagonist

The portal heart of the New Zealand hagfish (Eptatretus cirrhatus) was perfused in situ. Stroke volume, cardiac output and power output increased in response to increased preload, in accordance with Starling's law of the heart. A positive chronotropic effect was found when the input pressure increased from 0.05 to 0.1 kPa. Increased afterload decreased stroke volume and cardiac output. Power output peaked at an output pressure of 0.22 kPa, after which it decreased. There was no change in heart rate in response to increased afterload. In unanaesthetized resting animals, the pressure in the supraintestinal vein, which supplies the portal heart, ranged from 0.025 to 0.07 kPa (mean 0.040±0.005 kPa). The beta-adrenoceptor antagonist sotalol did not affect the response to different input and output pressures. Sotalol produced a significant decrease in heart rate and abolished the pressure-sensitive increase in heart rate. Bolus injections of adrenaline produced a transient increase in portal heart rate. The negative chronotropic response to sotalol and the response to adrenaline indicate the presence of an endogenous beta-adrenergic tonus on the portal heart.

MECHANICAL PERFORMANCE OF AN IN SITU PERFUSED HEART FROM THE TURTLE CHRYSEMYS SCRIPTA DURING NORMOXIA AND ANOXIA AT 5 C AND 15 C

1994 ◽  
Vol 191 (1) ◽  
pp. 207-229 ◽  
Author(s):  
A Farrell ◽  
C Franklin ◽  
P Arthur ◽  
H Thorarensen ◽  
K Cousins
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Stroke Volume ◽  
Power Output ◽  
Mechanical Performance ◽  
Perfused Heart ◽  
Inotropic Effects ◽  
Ventricular Mass

We developed an in situ perfused turtle (Chrysemys scripta) heart preparation to study its intrinsic mechanical properties at 5°C and 15°C using normoxic and anoxic perfusion conditions. The in situ preparation proved durable and stable. At 15°C and a spontaneous heart rate of 23.4 beats min-1, maximum stroke volume was 2.54 ml kg-1 body mass, maximum cardiac output was 62.5 ml min-1 kg-1 and maximum cardiac myocardial power output was 1.50 mW g-1 ventricular mass. There was good agreement between these values and those previously obtained in vivo. Furthermore, since the maximum stroke volume observed here was numerically equivalent to that observed in ventilating C. scripta in vivo, it seems likely that C. scripta has little scope to increase stroke volume to a level much beyond that observed in the resting animal through intrinsic mechanisms alone. The ability of the perfused turtle heart to maintain stroke volume when diastolic afterload was raised (homeometric regulation) was relatively poor. At 5°C, the spontaneous heart rate (8.1 beats min-1) was threefold lower and homeometric regulation was impaired, but maximum stroke volume (2.25 ml kg-1) was not significantly reduced compared with the value at 15°C. The significantly lower maximum values for cardiac output (18.9 ml min-1 kg-1) and power output (0.39 mW g-1 ventricular mass) at 5°C were largely related to pronounced negative chronotropy with only a relatively small negative inotropy. Anoxia had weak negative chronotropic effects and marked negative inotropic effects at both temperatures. Negative inotropy affected pressure development to a greater degree than maximum flow and this difference was more pronounced at 5°C than at 15°C. The maximum anoxic cardiac power output value at 15°C (0.77 mW g-1 ventricular mass) was not that different from values previously obtained for the performance of anoxic rainbow trout and hagfish hearts. In view of this, we conclude that the ability of turtles to overwinter under anoxic conditions depends more on their ability to reduce cardiac work to a level that can be supported through glycolysis than on their cardiac glycolytic potential being exceptional.

Control of the systemic heart and the portal heart of Myxine glutinosa

1996 ◽  
Vol 199 (6) ◽  
pp. 1429-1434 ◽  
Author(s):  
M Johnsson ◽  
M Axelsson
Keyword(s):  
Heart Rate ◽  
Stroke Volume ◽  
Myxine Glutinosa ◽  
Beta Adrenoceptor ◽  
Output Pressure ◽  
In Situ Perfusion ◽  
Adrenoceptor Antagonist ◽  
Heart Preparation ◽  
Spontaneous Contractions ◽  
Systemic Heart

The effects of preload and afterload on the performance of the systemic heart of the hagfish Myxine glutinosa were investigated before and during sotalol treatment using an in situ perfusion technique. Elevation of input pressure (preload) increased flow by means of increased stroke volume and heart rate in accordance with Starling's law of the heart, while increased output pressure (afterload) decreased flow mainly because of decreased stroke volume. Treatment with the beta-adrenoceptor antagonist sotalol did not change the quality of the responses to increased preload or afterload, although power output decreased by 40 % and flow rate was reduced by 35 % mainly due to a decrease in heart rate. Isolated preparations of the systemic heart and the portal heart provided information on the chronotropic effects of different agonists and antagonists. Both the systemic heart and the portal heart were insensitive to adrenergic and cholinergic agonists, adrenocorticotropic hormone and the cholinoceptor antagonist atropine. Sotalol treatment lowered the rate of spontaneous contractions by 30 % in the systemic heart preparation and by 21 % in the portal heart preparation. This study has given further evidence for the existence of a tonic beta-adrenoceptor stimulation of the hagfish systemic heart and portal heart, and demonstrated the importance of that stimulation in maintaining systemic heart performance.

scholarly journals Mechanisms responsible for the enhanced pumping capacity of the in situ winter flounder heart (Pseudopleuronectes americanus)

2007 ◽  
Vol 293 (5) ◽  
pp. R2112-R2119 ◽  
Author(s):  
Paula C. Mendonça ◽  
A. Gaylene Genge ◽  
Eric J. Deitch ◽  
A. Kurt Gamperl
Keyword(s):  
Cardiac Output ◽  
Power Output ◽  
High Volume ◽  
Filling Pressure ◽  
Winter Flounder ◽  
Mass Ratio ◽  
Pseudopleuronectes Americanus ◽  
Output Pressure

In situ Starling and power output curves and in vitro pressure-volume curves were determined for winter flounder hearts, as well as the hearts of two other teleosts (Atlantic salmon and cod). In situ maximum cardiac output was not different between the three species (∼62 ml·min−1·kg−1). However, because of the small size of the flounder heart, maximum stroke volume per milliliter per gram ventricle was significantly greater (2.3) compared with cod (1.7) and salmon (1.4) and is the highest reported for teleosts. The maximum power output of the flounder heart (7.6 mW/g) was significantly lower than that measured in the salmon (9.7) and similar to the cod (7.8) but was achieved at a much lower output pressure (4.9 vs. 8.0 and 6.2 kPa, respectively). Although the flounder heart could not perform resting levels of cardiac function at subambient pressures, it was much more sensitive to filling pressure, a finding supported by pressure-volume curves, which showed that the flounder's heart chambers were more compliant. Finally, we report that the flounder's bulbus:ventricle mass ratio (0.59) was significantly higher than in the cod (0.37) and salmon (0.22). These data, which support previous studies suggesting that the flatfish cardiovascular system is a high-volume, low-pressure design, show that vis-à-fronte filling is not important in flatfish, and that some fish can achieve high levels of cardiac output by vis-à-tergo filling alone; and suggest that a large compliant bulbus assists the flounder heart in delivering extremely large stroke volumes at pressures that do not become limiting.

The effects of preload, after load, and epinephrine on cardiac performance in the sea raven, Hemitripterus americanus

1982 ◽  
Vol 60 (12) ◽  
pp. 3165-3171 ◽  
Author(s):  
A. P. Farrell ◽  
K. MacLeod ◽  
W. R. Driedzic
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Stroke Volume ◽  
Work Load ◽  
Inotropic Effects ◽  
Fourfold Increase ◽  
Intrinsic Factors ◽  
Sea Raven

The preparation of the in situ heart was accomplished without any physical disturbance to the heart. The heart generated an intrinsic rhythm which was steady throughout the experiment and apparently was derived from the sinoatrial pacemaker. The power output developed by the in situ heart at physiological preloads and after loads was comparable to in vivo values. The effect of increasing preload (0 to 3 cmH2O) was a fourfold increase in stroke volume with little or no change in heart rate. When after load was changed (25 to 45 cmH2O) heart rate was unchanged and stroke volume was usually maintained. As a consequence, cardiac output was maintained by intrinsic factors alone at a higher work load. Epinephrine (10−9 to 10−5 M) in the perfusate produced relatively weak positive chronotropic and inotropic effects. The increase in cardiac output produced by epinephrine was small compared with the intrinsic changes evoked when preload was raised.

Physiological factors associated with the lower maximal oxygen consumption of master runners

1989 ◽  
Vol 66 (2) ◽  
pp. 949-954 ◽  
Author(s):  
A. M. Rivera ◽  
A. E. Pels ◽  
S. P. Sady ◽  
M. A. Sady ◽  
E. M. Cullinane ◽  
...  
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Stroke Volume ◽  
Maximal Oxygen Consumption ◽  
Maximal Heart Rate ◽  
Distance Runners ◽  
Physiological Factors ◽  
Factors Associated ◽  
Older Athletes ◽  
Maximal Cardiac Output

We examined the hemodynamic factors associated with the lower maximal O2 consumption (VO2max) in older formerly elite distance runners. Heart rate and VO2 were measured during submaximal and maximal treadmill exercise in 11 master [66 +/- 8 (SD) yr] and 11 young (32 +/- 5 yr) male runners. Cardiac output was determined using acetylene rebreathing at 30, 50, 70, and 85% VO2max. Maximal cardiac output was estimated using submaximal stroke volume and maximal heart rate. VO2max was 36% lower in master runners (45.0 +/- 6.9 vs. 70.4 +/- 8.0 ml.kg-1.min-1, P less than or equal to 0.05), because of both a lower maximal cardiac output (18.2 +/- 3.5 vs. 25.4 +/- 1.7 l.min-1) and arteriovenous O2 difference (16.6 +/- 1.6 vs. 18.7 +/- 1.4 ml O2.100 ml blood-1, P less than or equal to 0.05). Reduced maximal heart rate (154.4 +/- 17.4 vs. 185 +/- 5.8 beats.min-1) and stroke volume (117.1 +/- 16.1 vs. 137.2 +/- 8.7 ml.beat-1) contributed to the lower cardiac output in the older athletes (P less than or equal 0.05). These data indicate that VO2max is lower in master runners because of a diminished capacity to deliver and extract O2 during exercise.

Cardiovascular changes in the exercising emu

1983 ◽  
Vol 104 (1) ◽  
pp. 193-201 ◽  
Author(s):  
B. Grubb ◽  
D. D. Jorgensen ◽  
M. Conner
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Oxygen Consumption ◽  
Stroke Volume ◽  
Oxygen Content ◽  
Body Mass ◽  
Fold Increase ◽  
Exercise Heart Rate ◽  
Rate Of Oxygen Consumption ◽  
Cardiovascular Variables

Cardiovascular variables were studied as a function of oxygen consumption in the emu, a large, flightless ratite bird well suited to treadmill exercise. At the highest level of exercise, the birds' rate of oxygen consumption (VO2) was approximately 11.4 times the resting level (4.2 ml kg-1 min-1). Cardiac output was linearly related to VO2, increasing 9.5 ml for each 1 ml increase in oxygen consumption. The increase in cardiac output is similar to that in other birds, but appears to be larger than in mammals. The venous oxygen content dropped during exercise, thus increasing the arteriovenous oxygen content difference. At the highest levels of exercise, heart rate showed a 3.9-fold increase over the resting rate (45.8 beats min-1). The mean resting specific stroke volume was 1.5 ml per kg body mass, which is larger than shown by most mammals. However, birds have larger hearts relative to body mass than do mammals, and stroke volume expressed per gram of heart (0.18 ml g-1) is similar to that for mammals. Stroke volume showed a 1.8-fold increase as a result of exercise in the emus, but a change in heart rate plays a greater role in increasing cardiac output during exercise.

Cardiac Response During Trumpet Playing

2010 ◽  
Vol 25 (1) ◽  
pp. 16-21 ◽  
Author(s):  
Donald U Robertson ◽  
Lynda Federoff ◽  
Keith E Eisensmith
Keyword(s):  
College Students ◽  
Heart Rate ◽  
Heart Rate Variability ◽  
Cardiac Output ◽  
Stroke Volume ◽  
Cardiac Response ◽  
Physiological Efficiency ◽  
Rest Periods ◽  
Upper Register

Heart rate, heart rate variability, stroke volume, and cardiac output were measured while six college students and six professionals played trumpet. One-minute rest periods were followed by 1 minute of playing exercises designed to assess the effects of pitch and articulation. Heart rate and heart rate variability increased during playing, but stroke volume decreased. Changes in heart rate between resting and playing were greater for students, although beat-to-beat variability was larger for professionals in the upper register. These results suggest that expertise is characterized by greater physiological efficiency.

In the Loop—Left Ventricular Pressures

2011 ◽  
pp. 42-47
Author(s):  
James R. Munis
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Aortic Valve ◽  
Left Ventricle ◽  
Stroke Volume ◽  
Cardiovascular System ◽  
Aortic Root ◽  
Left Ventricular ◽  
Root Pressure ◽  
The Third

We've already looked at 2 types of pressure that affect physiology (atmospheric and hydrostatic pressure). Now let's consider the third: vascular pressures that result from mechanical events in the cardiovascular system. As you already know, cardiac output can be defined as the product of heart rate times stroke volume. Heart rate is self-explanatory. Stroke volume is determined by 3 factors—preload, afterload, and inotropy—and these determinants are in turn dependent on how the left ventricle handles pressure. In a pressure-volume loop, ‘afterload’ is represented by the pressure at the end of isovolumic contraction—just when the aortic valve opens (because the ventricular pressure is now higher than aortic root pressure). These loops not only are straightforward but are easier to construct just by thinking them through, rather than by memorization.

Hemodynamic Changes During Discontinuation of Mechanical Ventilation in Medical Intensive Care Unit Patients

2006 ◽  
Vol 15 (6) ◽  
pp. 580-593 ◽  
Author(s):  
Susan K. Frazier ◽  
Kathleen S. Stone ◽  
Debra Moser ◽  
Rebecca Schlanger ◽  
Carolyn Carle ◽  
...  
Keyword(s):  
Heart Rate ◽  
Mechanical Ventilation ◽  
Cardiac Output ◽  
Continuous Positive Airway Pressure ◽  
Stroke Volume ◽  
Cardiac Dysfunction ◽  
Airway Pressure ◽  
Positive Airway Pressure ◽  
Plasma Catecholamine ◽  
Medical Intensive Care

• Background Cardiac dysfunction can prevent successful discontinuation of mechanical ventilation. Critically ill patients may have undetected cardiac disease, and cardiac dysfunction can be produced or exacerbated by underlying pathophysiology. • Objective To describe and compare hemodynamic function and cardiac rhythm during baseline mechanical ventilation with function and rhythm during a trial of continuous positive airway pressure in medical intensive care patients. • Methods A convenience sample of 43 patients (53% men; mean age 51.1 years) who required mechanical ventilation were recruited for this pilot study. Cardiac output, stroke volume, arterial blood pressure, heart rate, cardiac rhythm, and plasma catecholamine levels were measured during mechanical ventilation and during a trial of continuous positive airway pressure. • Results One third of the patients had difficulty discontinuing mechanical ventilation. Successful patients had significantly increased cardiac output and stroke volume without changes in heart rate or arterial pressure during the trial of continuous positive airway pressure. Unsuccessful patients had no significant changes in cardiac output, stroke volume, or heart rate but had a significant increase in mean arterial pressure. The 2 groups of patients also had different patterns in ectopy. Concurrently, catecholamine concentrations decreased in the successful patients and significantly increased in the unsuccessful patients during the trial. • Conclusions Patterns of cardiac function and plasma catecholamine levels differed between patients who did or did not achieve spontaneous ventilation with a trial of continuous positive airway pressure. Cardiac function must be systematically considered before and during the return to spontaneous ventilation to optimize the likelihood of success.

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.

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