1. Experiment no. 2 FACTORS AFFECTING DRUG ACTION Influence of Chemical Structure
A. Macasaet, P. Macatangay, G. Madulara, C. Magno, P. Magsino, M. Malig, F. Mallari, S. Mamba, Jr., A. Manguba, Jr., M. Mangubat, S. Mansukhani, A. Manzana, C. Manzano, C. Maranion, K. Marasigan, E. Marayag, P. Marcelo, K. Marcial, E. Martin, M. Matematico, E. Matias, M. Maulion

2. General Objective
To determine the effects of Epinephrine, Dobutamine, and Terbutaline on heart rate and amplitude based on their chemical structure

3. Specific Objectives
To measure the rate and amplitude of baseline contractions of the turtle’s heart
To measure the rate and amplitude of contractions caused by each drug
To evaluate the results of each drug with p value set at 0.05 using one-way ANOVA

4. Animals Materials 8 Turtles per drug Kymograph set-up •Surgical gloves
Dissecting set •Tuberculin syringe
Kymograph paper •Tyrode solution
Paste •Heart hook
Cotton thread • Surgical thread

5. Drugs Dobutamine (250mg/20mL) Terbutaline 2.5mg/mL Epinephrine
(1:1000 ampule)

6. Methodology and Rationale
Apex of turtle’s heart was attached to a kymograph set up
2. Baseline rate and amplitude were obtained for 1 minute.
3. Drugs were directly instilled to the heart muscle (1 mL in 1 minute).
4. Rate and amplitude of contraction were recorded for three minutes from instillation

7. 5. Tyrode or NSS solution was used to wash the heart after each drug administration
6. Results were recorded and subjected to statistical analysis.

9. Drugs Epinephrine sympathomimetic, direct-acting
a potent vasoconstrictor and cardiac stimulant
acts on alpha-1, alpha-2, beta-1, and beta-2 receptors
increase peripheral resistance via alpha-1 vasoconstriction; beta-1 response is increased cardiac rate and output

10. Dobutamine synthetic catecholamine Beta agonist
beta-1 receptors >>> beta-2 receptors
lesser effect on alpha 1 receptors
primary activity: stimulation of the beta-adrenoceptors of the heart
 contractility,  cardiac output
Used often in patients with heart failure
( cardiac output  ventricular filling pressure)

11. used as a fast-acting bronchodilator
Terbutaline
Beta-2 selective
used as a fast-acting bronchodilator
often used as a short-term asthma treatment
tocolytic to delay premature labour.

12. Rationale of Drugs The structure of a sympathomimetic drug influences:
relative affinity for alpha and beta adrenergic receptors
intrinsic activity
pharmacokinetic properties

13. Structure-Activity Relationship
Increase of the size of alkyl substituents on the amino group
increase beta receptor activity :
 activity is further increased if there is an isopropyl substitution at the amino nitrogen.
2 selective agents: typically have a large amino substituent group.
as size of the substituent , activity at  receptors .

14. DOBUTAMINE
EPINEPHRINE
TERBUTALINE

15. Catecholamines have maximal  and  activity.
replacing the -OH groups at the 3 and 4 positions will reduce such activity
In terms of degree of reduction in potency at 3 & 4 positions:
3 position substitution > 4 position
Absence of the -OH groups
increases bioavailability & duration of action because the drug is no longer a substrate for COMT metabolism.
Replacing the -OH groups
also makes the resulting drug more widely distributed in the body

16. DOBUTAMINE
EPINEPHRINE
TERBUTALINE

17. substitution at the  carbon
prevents metabolism of a drug by MAO.
prolongs action of non-catecholamines.
substitution at the  carbon is typical for direct-acting agonists.

18. DOBUTAMINE
EPINEPHRINE
TERBUTALINE

19. Expected Results Rate: Epinephrine>Dobutamine>Terbutaline
Amplitude:

20. HYPOTHESIS
Ho: There are no significant differences among the effects of drugs
Ha: There are significant differences among the effects of drugs

21. Amplitude (% Difference)
GROUPS
EPINEPHRINE
DOBUTAMINE
TERBUTALINE A1
-20.0
-36.36
14.29 A2
-125.0
-30.0 B1
7.69
-50.0
37.5 B2
0.0
5.88 C1
-40.0
55.55
-14.29 C2 D1
-37.5
66.6
-25.0 D2
21.05
8.33

22. ANOVA: Single Factor SUMMARY Groups Count Sum Average Variance
Column 1 8
-24.22
Column 2
-43.17
Column 3
12.5
1.5625
ANOVA
Source of Variation SS df MS F
P-value
F crit
Between Groups 2
3.4668
Within Groups 21
Total 23

23. Since P value is not < 0.05, failed to reject null hypothesis.

24. RATE (% Difference) 15.22 -2.22 6.0 3.85 6.25 -4.08 -8.11 -4.76 2.44
GROUPS
EPINEPHRINE
DOBUTAMINE
TERBUTALINE A1
0.0
15.22
-2.22 A2
-11.63
6.0
3.85 B1
8.16
6.25
-4.08 B2
-8.11
-4.76 C1
8.33
2.44 C2
4.76
6.12 D1
2.08
2.70 D2
-11.90

25. ANOVA: Single Factor SUMMARY Groups Count Sum Average Variance
Column 1 8
-32.69
Column 2
35.06
4.3825
Column 3
-10.53
ANOVA
Source of Variation SS df MS F
P-value
F crit
Between Groups 2
3.4668
Within Groups 21
Total 23

26. Since P value is not < 0.05, failed to reject null hypothesis.

27. SOURCES OF ERROR
Bleeding
Trauma
Error on kymograph set-up

28. CONCLUSION
• Epinephrine, which is a direct acting, mixed alpha and beta adrenergic agonist, has the greatest effect in increasing the rate and amplitude of contractions, followed by Dobutamine, a selective beta-1 agonist, and Terbutaline, a beta-2 selective drug, has the least effect.
The chemical structures of Epinephrine, Dobutamine, and Terbutaline indicates their selectivity and effect on heart rate and amplitude of contraction.
The rate and amplitude of baseline contractions of the turtle’s heart was measured using the kymograph.
Using One-Way ANOVA, the resulting P values of Amplitude and Rate are not less than 0.05, therefore, there are no significant differences among the effects of drugs.

29. Thank you!

30. Heart Rate
Baseline
Epinephrine
Dobutamine
Terbutaline A 36 46 39 45 43 48 50 47 52 B 49 51 37 40 42 C 33 41 D

31. Amplitude 10 12 11 15 14 4 9 13 6 8 5 8.5 7 19 20 A B C D Baseline
Epinephrine
Dobutamine
Terbutaline A 10 12 11 15 14 4 9 13 B 6 8 5
8.5 C 7 D 19 20

32. Recommendation