Effect of Environmental Hypothermia on Vitelline Artery Blood Pressure and Vascular Resistance in the Stage 18, 21, and 24 Chick Embryo

Nakazawa, Makoto; Clark, Edward B.; Hu, Norman; Wispé, Jon R

doi:10.1203/00006450-198507000-00003

Cited by 26 publications

(17 citation statements)

References 8 publications

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“…In the control group the observed hemodynamic changes after the 4 min period were due to minor handling and to cooling of the embryo. It is known that chick embryo hemodynamics is greatly influenced by temperature (Nakazawa et al, 1985(Nakazawa et al, , 1986Wispé et al, 1983). Prolonged incubation at low temperatures can even give rise to cardiac malformations (de la Cruz et al, 1966).…”

Section: Discussionmentioning

confidence: 99%

“…For each clipped embryo a control embryo was measured, matched for the exact time interval between the first measurement before clipping and the second measurement directly after clipping. This was important since cooling of the embryo would take place despite the use of a thermoelement, and cooling influences the outcome of the measurements (Nakazawa et al, 1985;Wispé et al, 1983). The third measurement was performed 30 min after clipping, and the fourth to eighth recordings at 1, 2, 3, 4 and 5 h after clipping, respectively.…”

Section: Measurementsmentioning

confidence: 99%

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Acutely altered hemodynamics following venous obstruction in the early chick embryo

Vos

Ursem

Hop

et al. 2003

Journal of Experimental Biology

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SUMMARYIn the venous clip model specific cardiac malformations are induced in the chick embryo by obstructing the right lateral vitelline vein with a microclip. Clipping alters venous return and intracardiac laminar blood flow patterns,with secondary effects on the mechanical load of the embryonic myocardium. We investigated the instantaneous effects of clipping the right lateral vitelline vein on hemodynamics in the stage-17 chick embryo. 32 chick embryos HH 17 were subdivided into venous clipped (N=16) and matched control embryos(N=16). Dorsal aortic blood flow velocity was measured with a 20 MHz pulsed Doppler meter. A time series of eight successive measurements per embryo was made starting just before clipping and ending 5h after clipping. Heart rate, peak systolic velocity, time-averaged velocity, peak blood flow,mean blood flow, peak acceleration and stroke volume were determined. All hemodynamic parameters decreased acutely after venous clipping and only three out of seven parameters (heart rate, time-averaged velocity and mean blood flow) showed a recovery to baseline values during the 5h study period. We conclude that the experimental alteration of venous return has major acute effects on hemodynamics in the chick embryo. These effects may be responsible for the observed cardiac malformations after clipping.

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Section: Discussionmentioning

confidence: 99%

Section: Measurementsmentioning

confidence: 99%

Acutely altered hemodynamics following venous obstruction in the early chick embryo

Vos

Ursem

Hop

et al. 2003

Journal of Experimental Biology

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“…Hu et al (1) attempted to control for cycle length-dependent effects by selecting embryos with similar heart rates. The similarity of heart rate may have resulted from embryo temperature change during study; this is important because hypo-and hyperthermia affect cardiac output, arterial pressure, and afterload and thereby may affect filling characteristics (7,8). By using the thermal probe technique (3), isolated heart rate effects could be studied.…”

Section: Discussionmentioning

confidence: 99%

Heart Rate–Dependent Characteristics of Diastolic Ventricular Filling in the Developing Chick Embryo

1995

Pediatr Res

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The contributions of the early (passive) and late (active) components of ventricular filling have been reported to decrease and increase, respectively, during chick embryo cardiac development. We hypothesized that the observed changes in ventricular filling during early cardiac development results from a decrease in cycle length. We studied the effect of development and cycle length on atrioventricular inflow in 28 chick embryos, Hamilton-Hamburger stages 17, 24, and 26. Cycle length was perturbed (range 240-1040 ms) in ovo by transiently heating or cooling the sinus venosus. Atrioventricular inflow and dorsal aortic velocities were obtained by 20-MHz pulsed Doppler flowmeter and digitally recorded at 500 samples per second. Stroke volume was calculated from dorsal aortic velocity and crosssectional area. The atrioventricular inflow wave form was inte-The diastolic filling characteristics of the chick embryo ventricle change during developmental stages 12 through 27; the contributions of the early (passive) and late (active) components of ventricular filling have been reported to decrease and increase, respectively (1). Previous studies of altered embryonic heart rate using environmental temperature (I), cardiac pacing (2), and the thermal probe technique (3) have shown that early diastolic filling is heart rate dependent. This study further analyzes the differences in early ventricular filling velocities and flows resulting from heart rate perturbation. We found ventricular filling characteristics to be both developmentally determined and cycle length dependent. METHODSTwenty-eight fertile white Leghorn chicken eggs were incubated blunt end up at 38OC in a forced draft incubator to Hamburger-Hamilton stages 17 (n = 7, 3 d), 23-24 (n = 10, grated and partitioned by area and percentage of total into early (passive) and late (active) components using three methods. Regardless of method, the proportion of filling volume due to the early and late components was cycle length and stage dependent ( p < 0.05). The early and late filling volumes were large in the older embryos, and during cycle length decrease (heart rate increase) the early filling volume decrease was greater than the late filling volume decrease. When compared with the percentage of intrinsic heart rate, the percentage of stroke volume due to early filling decreased as heart rate increased and was greater in younger embryos at all heart rates. That due to late filling increased as the percentage of intrinsic heart rate increased. Ventricular filling characteristics are both developmentally determined and cycle length dependent. (Pediah. Res 37: 289-293, 1995) 4 d), and 25-26 (n = 11, 5 d) (4). Because of the similarity between adjacent stages, stage 23 (n = 1) and stage 24 (n = 9) embryos were consolidated into one group referred to as stage 24 (n = 10). Likewise, stages 25 (n = 2) and stage 26 (n = 9) were combined into stage 26 (n = 11). Eggs were placed in a heated sand bath (Bioengineering Department, Medical College of Georgia, Augusta, GA) under ...

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“…It is possible that temperatureinduced changes in afterload (9,10) may affect the rate and extent of ventricular relaxation (2) and, thereby, affect the ventricular filling characteristics. Alternatively, alterations in myocardial temperature may directly affect the calcium transport system (1 1) and, thereby, affect ventricular filling characteristics.…”

Section: Discussionmentioning

confidence: 99%

Relationship between Cardiac Cycle Length and Ventricular Relaxation Rate in the Chick Emhryo

1992

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ABSTRACI'. We hypothesized that during chick embryo cardiac development, cycle length decrease (heart rate increase) may be associated with developmental changes in the ventricular relaxation rate constant, T, which can be estimated from ventricular pressure decrease by the function P(t) = Pee-'", where Po = pressure at the time of minimum time derivative of ventricular pressure and t = time. Natural logarithm conversion results in a linear relation between In P(t) and t with slope of -117. We determined T in Hamburger-Hamilton stage 17-27 (d 3-5) embryos (n = 35) at intrinsic cycle length and in stage 24 embryos (n = 5) during cardiac cycle length perturbations with the hot-cold probe technique. Regression analysis of In P(t) from the minimum dP/dt until t = 30 ms was used to estimate r. Intrinsic cycle length decreased during development from stage 17 to 27 and T decreased linearly as cycle length decreased (r = 0.39, p < 0.005). Thus, during early development, both T and cycle length decrease (relaxation rate and heart rate increase). In stage 24 embryos, cycle length perturbation yielded a nonlinear cycle lengthdependent relation with T, with a plateau at cycle lengths less than intrinsic, i.e. T decreased with cycle length decrease to intrinsic cycle length, then r plateaued with further cycle length decrease. These findings demonstrate that ventricular relaxation rate is both maturation and cycle length dependent. The plateau effect of the T-cycle length relationship may be due to developmental limitations of the calcium transport system. (Pediatr Res 31: 480-482, 1992) Abbreviations dP/dt, time derivative of ventricular pressureIn the chick embryo, cardiac cycle length decreases (i.e. heart rate increases) during development and the associated changes in systolic cardiac performance (e.g. aortic blood flow, stroke volume, and cardiac work) have been well described (1). However, the relationship between diastolic function and develop mental heart rate changes has not been completely evaluated in the chick embryo.Ventricular relaxation rate is an important attribute of diastolic ventricular function, and we wondered if there might be developmental changes in ventricular relaxation as characterized by T, the time constant for isovolumic pressure decline (2). We hypothesized that the developmental changes in the relaxation rate are directly related to changes in cardiac cycle length. To test this hypothesis, we evaluated the relationship between cycle length and ventricular relaxation rate in chick embryos during early cardiac development. We found T to be dependent on both developmental stage and cardiac cycle length. MATERIALS AND METHODSFertile White Leghorn chicken eggs were incubated blunt end up at 38°C in a forced-draft incubator to Hamburger-Hamilton stages 17 (d 3) to 28 (d 5) (3). An egg was removed from the incubator and placed in a heated sand bath (Bioengineering Department, Medical College of Georgia) under a radiant warmer to maintain a constant egg temperature of 37-38°C throughout the ...

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Effect of Environmental Hypothermia on Vitelline Artery Blood Pressure and Vascular Resistance in the Stage 18, 21, and 24 Chick Embryo

Cited by 26 publications

References 8 publications

Acutely altered hemodynamics following venous obstruction in the early chick embryo

Acutely altered hemodynamics following venous obstruction in the early chick embryo

Heart Rate–Dependent Characteristics of Diastolic Ventricular Filling in the Developing Chick Embryo

Relationship between Cardiac Cycle Length and Ventricular Relaxation Rate in the Chick Emhryo

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