THE EFFECTS OF EPHEDRINE ON THE HEART RATE OF THE EMBRYO

THE EFFECTS OF EPHEDRINE
ON THE HEART RATE OF THE
120 HOUR EXPLANTED CHICK
EMBRYO
By:
Alana Gutierrez, Scott Radio,
and Dr. Jacqueline McLaughlin
The Electrical and Mechanical
Sequence of a Heartbeat
• Controlled by the sinoatrial
node, or the pacemaker of the
heart. In the chicken heart the
cardiac rhythm is kept by the sinus
venoeous.
• Sets the rate and timing of the
heart through electrical impulses.
• Change in the rate and output
of the heart is affected by the
changes in the autonomic nervous
system.
Figure 1. The Human Heart
Ephedrine
• Alkaloid extract from the Ma
Haung plant which is a smooth
muscle dilator used as a
treatment for respiratory
disorders such as asthma and
bronchitis.
• Used as an herbal dietary
supplement due to its
thermogenic qualities, which
increases caloric expenditure to
promote weight loss.
•
Figure 2. Chemical make-up of Ephedrine
alkaloid.
HO HO
CH2-CH2-NH2 HO_o
:@@, I_ @@ CH2-CH2-NH2 [email protected],
Norepinephrine
• Is a biogenic amine, a neurotransmitter of the sympathetic nervous
system produced from the amino acid tyrosine, and commonly known
as noradreline
• Is an amplifier of the sympathic nervous system that effectuates the
“fight or flight” response of the body.
• Often affect processes within the postsynaptic cell by binding to
receptors on their membranes which, in turn, affects the activities of
specific enzymes of the effector cell.
• Causes widespread vasoconstriction of blood vessels which results in
increased arterial blood pressure
• Binding to Alpha1 receptors, it effectively increases the amount of free
calcium, which leads increased heart rate and cardiac muscle
contraction.
How Ephedrine Works
•
•
•
•
•
A stimulant that acts on the
sympathetic nervous system via the
phrenic nerve. It induces presynaptic terminals norepinephrine
(noradrenaline-NA) into the
synaptic space.
Secondary effect of increasing
circulating adrenaline throughout
the body.
Binds directly to beta-receptors, in
place of norepinephrine, on the
surface of adipocytes.
Results in the increased production
of cyclic AMP within the effector
cell.
Figure 3. Effects of ephedrine in the
production of cyclic AMP
How Ephedrine Works
• The increase in cyclic AMP
increases the inflow of
calcium into the cardiac
muscle cells.
• The calcium influx leads to
an increase in heart rate and
in cardiac muscle
contraction.
• The vasodilatation of
coronary arteries results in
increased cardiac blood flow
as well.
Purpose
•To study the effects of various ephedrine solutions on the
heart rate (bpm) of the 120-hour chicken heart in vitro.
•Furthermore, to investigate any heart irregularities which
may occur following the exposure of ephedrine to the 120hour chicken heart in vitro.
Figure 4
56-hour
Chick Embryo
Methods
•
Three ephedrine solutions in chick saline were prepared from a 20%
ephedrine stock, with concentrations of 0.002%, 0.02%, and 0.2%.
•
An egg of 120-hours was obtained from an incubator and placed into a
cotton filled glass beaker at the lab station.
•
The egg shell was then cut with a scissors to produce a “window” which
was used to both visualize and explant the 120-hour chick embryo
according to the methods of Cruz (1995).
•
An in vivo heart rate was taken immediately and repeated five times, in
order to establish a control for the remainder of the experiment.
Figure 5
Explanting
the heart
Methods continued…
•
Following the methods of Cruz (1993), the embryo was then explanted from the
shell and placed into a chick saline solution.
•
A paper doughnut is used to frame the embryo and the membranes encasing the border
of the doughnut are excised.
•
The embryo is then removed from its shell and placed into a Syracuse dish that
contains a warmed chick saline solution.
•
The gooseneck lamp is used to heat embryo to a temperature that is close to being in
the incubator.
•
The ephedrine concentration being tested, 0.002% is placed into the Syracuse dish
containing the embryo via a pipette and the effects of this solution are recorded.
Figure 6
Figure 7
Donut Method
Embryo In Vitro
Embryo’s In Vivo Heart Rate
200
150
Embryo 1
bpm 100
Embryo 2
Embryo 3
50
Embryo 4
0
1
2
3
4
Number of Trials
5
Embryo’s In Vitro Heart Rate
160
140
120
100
bpm 80
60
40
20
0
Embryo 1
Embryo 2
Embryo 3
Embryo 4
1
2
3
4
Number of Trials
5
0.002% Solution
140
120
100
bpm
Embryo 1
80
60
40
20
0
Embryo 2
Embryo 3
Embryo 4
1
2
3
4
Number of Trials
5
0.02% Solution
140
120
100
bpm
Embryo 1
80
60
40
20
0
Embryo 2
Embryo 3
Embryo 4
1
2
3
4
Number of Trials
5
0.2% Solution
120
100
80
bpm
Embryo 1
60
Embryo 2
40
Embryo 3
20
Embryo 4
0
1
2
3
4
Number of Trials
5
Side Study- Embryo 1 with Alcohol
Solution
100
80
bpm
60
40
20
0
1
• Embryo 1
2
3
4
Number of Trials
5
Overview Data Interpretation
• The heart rate of the chick embryo is indeed
stimulated when the ephedrine concentration is
added.
• The experiment supported the hypothesis that
this increase will lead to observed heart
irregularities, such as arrhythmia's, which
ultimately lead to cardiac arrest.
Figure 6. Chick
Embryo
Conclusion
• The heart irregularities that were observed
lead us to believe that ephedrine is not a
satisfactory option for those looking for a
dietary supplement. While it has been
effective in treating those with respiratory
disorders, it must be medically regulated to
ensure its safe use.
References
Cruz, Y.P. 1993. Laboratory Exercises In Development Biology. Academic Press,
San Diego, California, 241 pages.
Colker, C.I., et al. Journal of American College Nutrition. Pages 16(5): al 16, 1997.
Davis, Ronald M., MD. “AMA Assists in Effort to Ban Ephedra.” February 21,
2003.
McLaughlin, Jacqueline and Elizabeth McCain (1991). “Development and
Physiological Aspects of the Chicken Embryonic Heart.”
Campbell, Neil and Jane Reese (2002). Biology. Benjamin/Cummings: CA. Sixth
Ed.
Prevost, M. (2003). “Ephedrine, Caffeine, and Aspirin”
<http://members.tripod.com/JPE_Sprotsscience/>
Figure 7.
Chick
Embryo