The Effects of Caffeine On the 4-Day Old Chicken Embryonic Heart Rate

Mazin Albert

Introduction Chicken Heart Development Heart forms from precardiac

mesodermal tubes 4 distinct regions 2 chambers

Figure 1- 33-Hour Chick Embryo

Figure 2- 48-Hour Chick Embryo

Figure 3- 72-Hour Chick Embryo

http://www.lv.psu.edu/jxm57/chicklab/outline.html

Chicken Heart Development

Caffeine The most commonly used

pharmacologic substance. Caffeine increases heart rate during

sleep (Bonnet, et. al. 2005) Caffeine increases blood pressure,

stroke volume, and cardiac output (Hartley, et. al. 2004).

Why Does Caffeine Do This?

Caffeine blocks adenosine on the surface of the heart causing higher HR.

Adenosine is an antiarrythmic agent. Caffeine also inhibits enzymes that

play a role in “turning off” stimulatory signals.

Purpose To determine the effects of various

concentrations of exogenously added caffeine on the 4-day in vitro chicken embryo heart.

Hypothesis The effects of exogenously added

caffeine at various concentrations to the in vitro 4-day chicken embryo heart will greatly increase the heart rate (bpm).

Figure 4- Chicken Embryo

Methods Prepared a stock 2% caffeine

solution. Then serial diluted the solution with chick saline to yield concentrations of 0.02, 0.002, 0.0002.

Methods Windowed a 4-day chick embryo

according to the methods of Cruz, et. al., 1993.

Determined the in vivo heart rate. Explanted the 4-day chick embryo

according to the methods of Cruz, et. al., 1993.

http://www.lv.psu.edu/jxm57/biol240.html#labsyl Figure 5- Windowed Egg

Methods Application of Caffeine

Administered 3 mL of each dilution to the in vitro chick embryo using the least concentration first.

Determined the in vitro heart rate of the chick embryo.

Repeated these steps in the order of increasing concentration.

Repeated these methods on at least six embryos.

Control The in vivo and in

vitro heart rates of a 4-day chick embryos before caffeine is exogenously applied.

Figure 6- In Vitro Chicken Embryo

Results

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Embryo 1 Embryo 2 Embryo 3 Embryo 4 Embryo 5 Embryo 6 Embryo 7 Average

Embryo Number

In Vivo Heart Rates (bpm)

Trial 1

Trial 2

Trial 3

Results

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Embryo 1 Embryo 2 Embryo 3 Embryo 4 Embryo 5 Embryo 6 Embryo 7 Average

Embryo Number

In Vitro Heart Rates w/o Caffeine

Trial 1

Trial 2

Trial 3

Results

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Embryo 1 Embryo 2 Embryo 3 Embryo 4 Embryo 5 Embryo 6 Embryo 7 Average

Embryo Number

In Vitro Heart Rates - .0002

Trial 1

Trial 2

Trial 3

Results

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Embryo 1 Embryo 2 Embryo 3 Embryo 4 Embryo 5 Embryo 6 Embryo 7 Average

Embryo Number

In Vitro Heart Rates - 0.002

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Trial 2

Trial 3

Results

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Embryo 1 Embryo 2 Embryo 3 Embryo 4 Embryo 5 Embryo 6 Embryo 7 Average

Embryo Number

In Vitro Heart Rates - 0.02

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Trial 2

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Caffeine Concentration

Average Heart Rate (bpm)

Average 124 82 106 89 62

In VivoIn Vitro w/o

CaffeineIn Vitro - 0.0002

In Vitro - 0.002

In Vitro - 0.02

Data Interpretation In vivo heart rate is higher than the in

vitro heart rate. 5 out of 7 embryos had an increase in

heart rate between in vitro w/o solution to in vitro with 0.0002.

3 out of 7 embryos had an increase in heart rate between in vitro with 0.0002 and in vitro with 0.002.

Arrhythmias were noted, mostly tachycardia and atrial flutter.

Conclusion Data did not support the hypothesis. Although the initial concentration

caused an increase in heart rate, higher concentrations of caffeine did not always result in a higher heart rate.

Overall trend showed a decrease in heart rate.

Siamese Twins

Figure 7- Siamese Twins Chick Embryo

Future Experiments After applying caffeine, incubate

embryo, until it has fully developed to see if there were any adverse effects on the overall development of the chicken.

Questions Thank you for

listening to my presentation.

Are there any questions?

Figure 8- Caffeine Molecule

References “Adenosine”. 2006. Wikipedia Foundation Inc. 22 March 2006.

<http://en.wikipedia.org/wiki/Adenosine#Action_on_the_heart.> Bonnet, Michael, Ph.D., Manuel Tancer, M.D., Thomas Uhde, M.D., Vikram

K. Yeragani, M.D. “Effects of caffeine on heart rate and QT variability during sleep.” Depression and Anxiety. 2005. Vol. 22, Issue 3. pgs 150-155.

Cruz, Y.P. 1993. Laboratory exercises in developmental biology. Academic Press, San Diego, California, 241 pages. [ISBN 0-12-198390-0] [book]

Hartley, Terry, Lovallo, Wiliam, Whitsett, Thomas. “Cardiovascular Effects of Caffeine in Men and Women.” The American Journal of Cardiology. 2004. Vol. 93. pgs. 1022-1026.

Hebert, Terry. “Re: How, and why does caffeine affect the rate of a daphnia’s heart rate?”. 1999. MadSci Network. 22 March 2006. <http://www.madsci.org/posts/archives/jul99/931925101.Zo.r.html.>

McLaughlin, Jacqueline and McCain, Elizabeth. Development and Physiological Aspects of the Chicken Embryonic Heart. 1996. 12 Feb. 2005. <http://www.lv.psu.edu/jxm57/chicklab/outline.html>