Interruption of cardiac output does not affect short-term growth and metabolic rate in day 3 and 4 chick embryos

2000 ◽  
Vol 203 (24) ◽  
pp. 3831-3838 ◽  
Author(s):  
W.W. Burggren ◽  
S.J. Warburton ◽  
M.D. Slivkoff
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Body Mass ◽  
Regression Line ◽  
Heart Beat ◽  
Chick Embryos ◽  
Simple Diffusion ◽  
Significant Difference ◽  
Vertebrate Embryos ◽  
Cervical Flexure

The heart beat of vertebrate embryos has been assumed to begin when convective bulk transport by blood takes over from transport by simple diffusion. To test this hypothesis, we measured eye growth, cervical flexure and rates of oxygen consumption (V(O2)) in day 3–4 chick embryos denied cardiac output by ligation of the outflow tract and compared them with those of embryos with an intact cardiovascular system.Eye diameter, used as the index for embryonic growth, increased at a rate of approximately 4.5-5 % h(−)(1) during the observation period. There was no significant difference (P>0.1) in the rate of increase in eye diameter between control (egg opened), sham-ligated (ligature present but not tied) and ligated embryos. Similarly, the normal progression of cervical flexure was not significantly altered by ligation (P>0.1). V(O2) (ml O(2)g(−)(1)h(−)(1)) at 38 degrees C, measured by closed respirometry, was not significantly different (P>0.1) on day 3 in sham-ligated (14.5+/−1.9 ml O(2)g(−)(1)h(−)(1)) and ligated 17.6+/−1.8 ml O(2)g(−)(1)h(−)(1)) embryos. Similarly, on day 4, V(O2) in sham-ligated and ligated embryos was statistically the same (sham-ligated 10. 5+/−2.9 ml O(2)g(−)(1)h(−)(1); ligated 9.7+/−2.9 ml O(2)g(−)(1)h(−)(1)). Expressed as a linear function of body mass (M), V(O2) in sham-ligated embryos was described by the equation V(O2)=−0.48M+24.06 (r(2)=0.36, N=18, P<0.01), while V(O2) in ligated embryos was described by the equation V(O2)=−0.53M+23.32 (r(2)=0.38, N=16, P<0.01). The regression line describing the relationship between body mass and V(O2) for pooled sham-ligated and ligated embryos (the two populations being statistically identical) was V(O2)=−0.47M+23.24. The slope of this regression line, which was significantly different from zero (r(2)=0.30, N=34, P<0.01), was similar to slopes calculated from previous studies over the same range of body mass.Collectively, these data indicate that growth and V(O2) are not dependent upon cardiac output and the convective blood flow it generates. Thus, early chick embryos join those of the zebrafish, clawed frog and axolotl in developing a heart beat and blood flow hours or days before required for convective oxygen and nutrient transport. We speculate that angiogenesis is the most likely role for the early development of a heart beat in vertebrate embryos.

Single-breath breath-holding estimate of pulmonary blood flow in man: comparison with direct Fick cardiac output

1989 ◽  
Vol 76 (6) ◽  
pp. 673-676 ◽  
Author(s):  
A. H. Kendrick ◽  
A. Rozkovec ◽  
M. Papouchado ◽  
J. West ◽  
G. Laszlo
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Pulmonary Blood Flow ◽  
Hold Time ◽  
Normal Subjects ◽  
Breath Holding ◽  
Breath Hold ◽  
Single Breath ◽  
Significant Difference ◽  
Cardiac Disorders

1. Resting pulmonary blood flow (Q.), using the uptake of the soluble inert gas Freon-22 and an indirect estimate of lung tissue volume, has been estimated during breath-holding (Q.c) and compared with direct Fick cardiac output (Q.f) in 16 patients with various cardiac disorders. 2. The effect of breath-hold time was investigated by comparing Q.c estimated using 6 and 10 s of breath-holding in 17 patients. Repeatability was assessed by duplicate measurements of Q.c in the patients and in six normal subjects. 3. Q.c tended to overestimate Q.f, the bias and error being 0.09 l/min and 0.59, respectively. The coefficient of repeatability for Q.c in the patients was 0.75 l/min and in the normal subjects was 0.66 1/min. For Q.f it was 0.72 l/min. There was no significant difference in Q.c measured at the two breath-hold times. 4. The technique is simple to perform, and provides a rapid estimate of Q., monitoring acute and chronic changes in cardiac output in normal subjects and patients with cardiac disease.

Cardiac output and peripheral resistance during larval development in the anuran amphibian Xenopus laevis

1995 ◽  
Vol 269 (5) ◽  
pp. R1126-R1132 ◽  
Author(s):  
P. C. Hou ◽  
W. W. Burggren
Keyword(s):  
Cardiac Output ◽  
Xenopus Laevis ◽  
Larval Development ◽  
Body Mass ◽  
General Pattern ◽  
Peripheral Resistance ◽  
Cardiac Work ◽  
Common Pattern ◽  
Hemodynamic Variables ◽  
Vertebrate Embryos

Stroke volume (SV) and cardiac output (CO) were measured in anesthetized larvae of Xenopus laevis from hatching (3 mg) to the end of metamorphosis (approximately 1 g). CO and SV were calculated from videotaped images of the intact beating heart. SV increased from 2.4 x 10(-3) microliters at 3 mg body mass to 7.6 microliters at 1 g. CO increased from 0.25 microliter/min at 3 mg to 623 microliters/min at 1 g. With use of CO, along with arterial pressures from another study [P.-C. L. Hou and W. W. Burggren. Am. J. Physiol. 269 (Regulatory Integrative Comp. Physiol. 38): R1120-R1125, 1995], peripheral resistance and cardiac work were also calculated. Resistance decreased rapidly from 701 peripheral resistance units (PRU, mmHg.s.mm-3) at 3 mg body mass to 79 PRU at 20 mg and gradually declined toward 0.9 PRU at 1 g. Cardiac work increased from 0.06 dyn.mm at 3 mg body mass to 1.27 dyn.mm at 20 mg and then climbed sharply to 717 dyn.mm at 1 g. The general pattern of change in hemodynamic variables (except heart rate) during larval development is similar in Xenopus laevis and chick embryos, suggesting a common pattern for hemodynamic development in vertebrate embryos/larvae.

The Haemodynamic Effects of Metabolic Acidosis in the Rat

1976 ◽  
Vol 50 (3) ◽  
pp. 177-184 ◽  
Author(s):  
J. Yudkin ◽  
R. D. Cohen ◽  
Barbara Slack
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Blood Flow ◽  
Cardiac Output ◽  
Metabolic Acidosis ◽  
Renal Blood Flow ◽  
Hepatic Blood Flow ◽  
Conscious Rats ◽  
Blood Ph ◽  
Significant Difference

1. The effect of metabolic acidosis of 4–6 h duration on cardiac output, blood pressure, heart rate, and hepatic and renal blood flow has been studied in the rat. 2. In anaesthetized rats, blood pressure and heart rate fell linearly with blood pH in both sham-operated and nephrectomized rats. There was no significant difference between the two groups in the effect of acidosis on either variable. 3. Cardiac output showed a significant fall with increasing acidosis in the conscious rat. 4. Estimated hepatic blood flow in conscious rats showed a significant positive correlation with blood pH in both sham-operated and nephrectomized animals. There was no significant difference in estimated hepatic blood flow between the two groups of animals at any blood pH. 5. In conscious rats, increasing acidosis caused a progressive decrease in estimated renal blood flow. 6. It is concluded that the increase in the previously described apparent renal contribution to lactate removal in the acidotic rat cannot be explained by any circulatory effect mediated by the kidney. The possible relevance of the findings to lactate homeostasis is discussed.

Importance of injection site for coronary blood flow determinations by microspheres in rats

1982 ◽  
Vol 242 (1) ◽  
pp. H94-H97 ◽  
Author(s):  
P. Wicker ◽  
R. C. Tarazi
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Injection Site ◽  
Coronary Blood Flow ◽  
Left Atrial ◽  
Left Ventricular ◽  
Significant Difference ◽  
Standard Deviations

Because coronary blood flow (CBF) determinations require that blood and microspheres be uniformly mixed in the root of the aorta, we developed a technique of left-atrial (LA) catheterization in rats and compared the variability of results obtained by LA injection and left-ventricular (LV) injection as regards systemic [cardiac output (CO)], proximal (coronary), and distal (renal, cerebral) flows in anesthetized animals. CBF values averaged 410 +/- 224 and 358 +/- 99 (SD) ml.min-1.100 g-1 from LV and LA injection, respectively, or 5.7 +/- 2.9 and 4.9 +/- 1.3 (SD) %CO. The variability with LA injection was significantly lower than with LV injection as shown by the marked differences in standard deviations obtained with the two methods (224 vs. 99 ml.min-1.100 g-1 or 2.9 vs. 1.3 %CO, P greater than 0.01). In contrast, no significant difference in variability was found for either CO or more distal regional flows. These results indicate that LV injections might be adequate for systemic flow and regional flows to relatively distal beds but that accurate measurements of CBF require LA injection of microspheres.

scholarly journals Effects of head-down-tilt bed rest on cerebral hemodynamics during orthostatic stress

1997 ◽  
Vol 83 (6) ◽  
pp. 2139-2145 ◽  
Author(s):  
Rong Zhang ◽  
Julie H. Zuckerman ◽  
James A. Pawelczyk ◽  
Benjamin D. Levine
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Cerebral Autoregulation ◽  
Orthostatic Intolerance ◽  
Bed Rest ◽  
Cerebral Hemodynamics ◽  
Orthostatic Stress ◽  
Orthostatic Tolerance ◽  
Mean Velocity ◽  
Significant Difference

Zhang, Rong, Julie H. Zuckerman, James A. Pawelczyk, and Benjamin D. Levine. Effects of head-down-tilt bed rest on cerebral hemodynamics during orthostatic stress. J. Appl. Physiol. 83(6): 2139–2145, 1997.—Our aim was to determine whether the adaptation to simulated microgravity (μG) impairs regulation of cerebral blood flow (CBF) during orthostatic stress and contributes to orthostatic intolerance. Twelve healthy subjects (aged 24 ± 5 yr) underwent 2 wk of −6° head-down-tilt (HDT) bed rest to simulate hemodynamic changes that occur when humans are exposed to μG. CBF velocity in the middle cerebral artery (transcranial Doppler), blood pressure, cardiac output (acetylene rebreathing), and forearm blood flow were measured at each level of a ramped protocol of lower body negative pressure (LBNP; −15, −30, and −40 mmHg × 5 min, −50 mmHg × 3 min, then −10 mmHg every 3 min to presyncope) before and after bed rest. Orthostatic tolerance was assessed by using the cumulative stress index (CSI; mmHg × minutes) for the LBNP protocol. After bed rest, each individual’s orthostatic tolerance was reduced, with the group CSI decreased by 24% associated with greater decreases in cardiac output and greater increases in systemic vascular resistance at each level of LBNP. Before bed rest, mean CBF velocity decreased by 14, 10, and 45% at −40 mmHg, −50 mmHg, and maximal LBNP, respectively. After bed rest, mean velocity decreased by 16% at −30 mmHg and by 21, 35, and 39% at −40 mmHg, −50 mmHg, and maximal LBNP, respectively. Compared with pre-bed rest, post-bed-rest mean velocity was less by 11, 10, and 21% at −30, −40, and −50 mmHg, respectively. However, there was no significant difference at maximal LBNP. We conclude that cerebral autoregulation during orthostatic stress is impaired by adaptation to simulated μG as evidenced by an earlier and greater fall in CBF velocity during LBNP. We speculate that impairment of cerebral autoregulation may contribute to the reduced orthostatic tolerance after bed rest.

Body, eye, and chorioallantoic vessel growth are not dependent on cardiac output level in day 3–4 chicken embryos

2004 ◽  
Vol 287 (6) ◽  
pp. R1399-R1406 ◽  
Author(s):  
Warren Burggren ◽  
Sheva Khorrami ◽  
Alan Pinder ◽  
Tiffany Sun
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Body Mass ◽  
Chorioallantoic Membrane ◽  
Blood Perfusion ◽  
Ventricular Outflow Tract ◽  
Tissue Growth ◽  
Wide Range ◽  
Vessel Growth ◽  
Eye Diameter

Normal aerobic metabolic rates persist in the early chicken embryo after elimination of cardiac output, but the dependence of tissue growth and differentiation on blood flow is unknown in these early stages. We partially ligated (25–50% occlusion) the ventricular outflow tract of Hamburger-Hamilton stage (HH) 16–18 embryos, producing a wide range of cardiac output. For the next ∼48 h (to HH 24), we measured heart rate (HR), stroke volume (SV), and cardiac output (CO), as well as these growth indicators: eye diameter, chorioallantoic vessel density, and body mass. Acutely, HR declined with partial ligation (from 108 to 98 beats/min). Paradoxically, SV and CO decreased sharply in most embryos but increased in others, collectively producing the desired large variation (up to 25-fold) in CO and permitting assessment of tissue growth over a very large range of blood perfusion. Eye diameter doubled (from 0.6 to 1.2 mm) with development from HH 16 to HH 24, but within a developmental cohort there was no significant correlation between eye diameter and CO over a 25-fold range of CO. Similarly, chorioallantoic membrane vessel index was independent of CO over the CO range at all stages. Finally, body mass increase during development was not significantly affected by partial conal truncal ligation. Collectively, these data suggest that normal eye and vessel growth and body mass accumulation occur independent of their rate of blood perfusion, supporting the hypothesis of prosynchronotropy—that the heart begins to beat and generate blood flow in advance of the actual need for convective blood flow to tissues.

scholarly journals Distribution of cardiac output to the brain across the adult lifespan

2016 ◽  
Vol 37 (8) ◽  
pp. 2848-2856 ◽  
Author(s):  
Chang-Yang Xing ◽  
Takashi Tarumi ◽  
Jie Liu ◽  
Yinan Zhang ◽  
Marcel Turner ◽  
...  
Keyword(s):  
Body Mass Index ◽  
Blood Flow ◽  
Cardiac Output ◽  
Cerebral Blood Flow ◽  
Body Mass ◽  
Pulse Wave ◽  
Adult Lifespan ◽  
Output Ratio ◽  
The Brain ◽  
Distribution Of Cardiac Output

A widely accepted dogma is that about 15–20% of cardiac output is received by the brain in healthy adults under resting conditions. However, it is unclear if the distribution of cardiac output directed to the brain alters across the adult lifespan and is modulated by sex or other hemodynamic variables. We measured cerebral blood flow/cardiac output ratio index in 139 subjects (88 women, age 21–80 years) using phase-contrast magnetic resonance imaging and echocardiography. Body mass index, cardiac systolic function (eject fraction), central arterial stiffness (carotid-femoral pulse wave velocity), arterial pressure, heart rate, physical fitness (VO2 max), and total brain volume were measured to assess their effects on the cardiac output–cerebral blood flow relationship. Cerebral blood flow/cardiac output ratio index decreased by 1.3% per decade associated with decreases in cerebral blood flow ( P < 0.001), while cardiac output remained unchanged. Women had higher cerebral blood flow, lower cardiac output, and thus higher cerebral blood flow/cardiac output ratio index than men across the adult lifespan. Age, body mass index, carotid-femoral pulse wave velocity, and arterial pressure all had negative correlations with cerebral blood flow and cerebral blood flow/cardiac output ratio index ( P < 0.05). Multivariable analysis adjusted for sex, age showed that only body mass index was negatively associated with cerebral blood flow/cardiac output ratio index (β = −0.33, P < 0.001). These findings demonstrated that cardiac output distributed to the brain has sex differences and decreases across the adult lifespan and is inversely associated with body mass index.

scholarly journals Head-up suspension in humans: effects on sympathetic vasomotor activity and cardiovascular responses

1998 ◽  
Vol 84 (5) ◽  
pp. 1513-1519 ◽  
Author(s):  
A. S. M. Shamsuzzaman ◽  
Y. Sugiyama ◽  
A. Kamiya ◽  
Q. Fu ◽  
T. Mano
Keyword(s):  
Heart Rate ◽  
Blood Flow ◽  
Cardiac Output ◽  
Stroke Volume ◽  
Left Atrial ◽  
Muscle Sympathetic Nerve Activity ◽  
Cardiovascular Responses ◽  
Left Atrial Diameter ◽  
Calf Blood Flow ◽  
Significant Difference

We hypothesized that muscle sympathetic nerve activity (MSNA) and cardiovascular responses to the conventional head-up tilt (HUT) are different from those to head-up suspension (HUS) because of antigravity muscle activity. The MSNA from the tibial nerve, heart rate, blood pressure, stroke volume, cardiac output, and calf blood flow were measured in 13 healthy young subjects. Left atrial diameter was measured by two-dimensional echocardiography in another nine subjects. The resting MSNA and cardiovascular responses at a low level (20°) of orthostasis were similar during both modes. At higher levels (40 and 60°), the responses of MSNA, heart rate, stroke volume, and cardiac output were significantly stronger and there was a smaller reduction in calf blood flow during HUT than during HUS ( P < 0.05). Left atrial diameter was decreased significantly from the resting values during HUT and HUS without any significant difference between the modes of orthostasis. The results provide evidence that the engagement of antigravity muscles during HUT may have additive effects on sympathetic vasoconstrictor and cardiovascular responses to orthostatic stress.

The Blood Pressure of Giraffes

2021 ◽  
pp. 187-215
Author(s):  
Graham Mitchell
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Blood Flow ◽  
Cardiac Output ◽  
Hydrostatic Pressure ◽  
Left Ventricle ◽  
Stroke Volume ◽  
Body Mass ◽  
The Brain ◽  
Very High

As discussed in this chapter, giraffes have, compared with any other mammal, a very high mean blood pressure of ~250 mmHg. Human blood pressure is ~90 mmHg. Its size is determined by the length of the neck, the height of the head above the heart, by hydrostatic pressure generated by gravity acting on the column of blood in the carotid artery, and contractions of the heart muscles: blood pressure must be high enough to ensure that blood reaches the brain. Uniquely in giraffes blood pressure is regulated by receptors that are located in both the carotid and occipital arteries. Once thought to be ~2.5% of body mass the heart is smaller (~0.5% of body mass) but its muscle walls, especially of the interventricular wall and left ventricle wall, are exceptionally thick (up to 8 cm). The relative cardiac output is the same as in other mammals (~5 L 100 kg–1 of body mass) through a combination of a higher than predicted heart rate (70 b min–1 vs 50 b min–1) and smaller than predicted stroke volume (~0.7 ml kg–1 body mass vs 1.2 ml kg–1). Stroke volume is small because the left ventricle muscle wall is thick. The origin of high blood pressure is the resistance to blood flow, which is about twice what it is in other mammals. The higher resistance results from a combination of the thick muscular walls and narrow lumens of a giraffe’s blood vessels and unique mechanisms that regulate blood flow to the brain.

Post-prandial blood flow to the gastrointestinal tract is not compromised during hypoxia in the sea bassDicentrarchus labrax

2002 ◽  
Vol 205 (18) ◽  
pp. 2891-2896 ◽  
Author(s):  
Michael Axelsson ◽  
Jordi Altimiras ◽  
Guy Claireaux
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Gastrointestinal Tract ◽  
Body Mass ◽  
Relative Proportion ◽  
Splanchnic Blood Flow ◽  
Reflex Regulation ◽  
Local Factors ◽  
Before And After ◽  
Initial Hypothesis

SUMMARYThe hypothesis that the increase in post-prandial splanchnic blood flow will be reduced during hypoxia to prioritise blood flow to other organs was tested by measuring cardiac output and gut blood flow during a stepwise hypoxic challenge (five steps, from 20.6 to 3.9 kPa, 5 min of exposure to each level) before and after feeding (equivalent to 2.9% of body mass). Splanchnic blood flow, both absolute and relative to cardiac output, increased after feeding. Mean post-prandial gut blood flow increased by 71% (from 9.6±1.6 to 14.9±1.6 ml min-1 kg-1, means± S.E.M.). Before feeding, gut blood flow was 24.0% of cardiac output,and this increased significantly 24 h after feeding to 34.0%. The absolute post-prandial increase in gut blood flow (5.3±0.9 ml min-1kg-1) was paralleled by an increase in cardiac output(5.4±2.1 ml min-1 kg-1). Hypoxia decreased gut blood flow significantly from 9.6±1.6 to 3.7±1.1 ml min-1 kg-1, corresponding to a decrease in relative gut blood flow from 24 % to 13%. Contrary to our initial hypothesis, and although post-prandial absolute blood flow decreases during hypoxia, the relative proportion of cardiac output reaching the gut did not decrease (34.6%pre-hypoxia versus 26.7% during hypoxia), unlike the situation in non-feeding fish. We propose that, following feeding, relative gut blood flow is maintained because splanchnic hyperaemia occurs as a result of the release of local factors; consequently the reflex vasoconstriction of the gastrointestinal vasculature during hypoxia is not as effective in decreasing gut blood flow as it was before feeding because local hyperaemia out-competes the reflex regulation.

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