PHYS20009 Research Based Physiology

PART 1:
Scenario:
In the Marvel Research Laboratory Dr Hulk has been coming up with a secret
formula to turn any animal (human or any mammal) into a super
powerful force. This magic elixir will give the recipient super speed
and super strength. He has finally come up with a compound that
he wants to test. Indeed, when he gave the compound to his first
laboratory rats Dr Hulk observed the rats had:
1. faster reaction times when stimulated,
2. they could carry greater weight (greater strength)
3. and they could carry weight for a longer period of time
(greater endurance).
Dr Hulk wants to test this formula further to determine the site of action for his compound. He
wants to determine where the compound might be producing its effects. He wants to identify
the site of action and the mechanism by which his compound is producing its effects
He has recruited you to his laboratory to help him determine the
i) site of action and
ii) mechanisms of action
of his elixir. You are intrigued by this compound and agree to work with him.
Question 1) (20 marks)
Using your knowledge of physiology, identify 4 potential mechanisms including their site of
action where this formula could be working to produce any of the effects observed by Dr Hulk.
Note: You can choose from any of the observations above. You need to make it clear in your
description which observation your proposed mechanism relates to.
! The physiological mechanisms must be accurate.
! You may choose any, or all of the observations recorded by Dr Hulk.
! You do not have to propose mechanisms for each observation but you must identify 4
mechanisms that relate to the observations.
! For example, you may choose to propose 4 mechanisms on how the formula might
increase strength. Or you may propose 2 mechanisms for faster reaction time, and 2
mechanisms on greater endurance. The choice is all yours!
You will be assessed on the appropriateness and accuracy of the mechanism to the
observation indicated, and the explanation for how this mechanism relates to the observation.
To study this potion further, you will need to conduct a number of experiments.
Question 2) (15 marks)
Write a manipulation hypothesis for your study, using one of the mechanisms you have
identified in Question 1.
! It should be obvious from your hypothesis which mechanism you have chosen to
examine so you do not need to repeat it here.
! Remember the components that goes into a good hypothesis.
Question 3) (15 marks)
a) To test your hypothesis, describe what type of preparation (see note below) you would
choose to use in your experiment. 5 marks
b) Explain in detail your rationale for choosing this preparation.
! Justify how will this preparation allow you to test your chosen mechanism. You should be
specific on the sites of action and the mechanism that you are examining. 10 marks
Note: You don’t need to know the exact name of the preparation, but you need to describe
whether you wish to use cells, tissue, organ or whole organism.
! You should identify the exact components you wish to include in your experimental model.
! Justify how this preparation will allow you to test your proposed mechanism in your
hypothesis in Question 2.
! You should explain what you want to test and whether cells, tissue, organ or organism will
allow you to test your proposed mechanism.
! You should clearly specify how and why this chosen preparation will allow you to test your
proposed mechanism.
Since the observation was initially made in a rat, you will continue your experiment in rats
too.
You will be assessed on your logic and explanation for your choice of preparation. You will also
be assessed on the continuity with your proposed mechanism (i.e. does your chosen
preparation actually test the proposed mechanism).
Example from using preparations from Week 3 in-class task:
The proposed mechanism is that Drug X produces an increase in arterial blood pressure by
causing vasoconstriction as it activates the alpha-adrenergic receptors. An isolated blood
vessel was chosen as this preparation allows us to determine if drug X is acting directly at the
alpha-adrenergic receptors on the arteriole smooth muscles. An isolated blood vessel
preparation will also allow us to measure vasoconstriction in arterioles.
[Reflect on the example given above, can it be more detailed? What additional information or
explanation could be provided to better explain how an isolated blood vessel might allow you to
specifically test the proposed mechanism?]
Question 4) (25 marks)
Design an experiment to test your hypothesis.
Include (but not limited to) the following points in your experimental design:
! Consider whether you would use serial or parallel controls and explain your reasoning.
! What factors should be controlled for in the experiments and why?
! What will you measure and when?
! Provide a brief experimental timeline of your experimental design.
Be sure to revisit the notes on experimental design and study the feedback provided in your
Week 3 In-Class Group Task.
Note: Dr Hulk has an amazing laboratory and has all the equipment you might need. However,
this is not a magical lab and reality of what you can observe still applies.
! You should limit your measurements to factors and mechanisms discussed in Workshop 3 -
Model Systems.
! Do not worry about HOW you will measure it, or what equipment you will use.
! Focus on WHAT you will measure and how this will address your proposed mechanism, and
the factors that you should control for in your experimental design.
! The limitations identified in Week 3 Workshop should be considered and applied in your
experimental design.
! You will be assessed on the detail of what you are measuring and whether this addresses
your proposed mechanism in Question 2. The appropriateness of your experimental design
in answering your hypothesis will also be important.
Continuity from Question 1 to 4 is essential
PART 2:
Your lab mate, Carly Kul, has been studying the effect of another compound, Lavblod, on the
arterial blood pressure of rats. She has some preliminary data that suggests this drug may
lower blood pressure and thus has potential as an anti-hypertensive drug.
She wants your advice on how she should go about presenting and analysing her data to
determine if Lavblod is indeed lowering blood pressure. Carly would like to know if the
application of Lavblod is decreasing arterial blood pressure in rats.
Read through her experimental protocol below, look at her data and answer the questions
that follow.
Mean arterial pressure (mmHg)
Days Rat 1 Rat 2 Rat 3 Rat 4
1 133 140 130 143
2 132 143 135 141
3 131 139 133 140
4 134 141 134 142
5 135 144 136 143
6 140 140 133 142
7 133 143 132 142
8 (start feeding
Lavblod)
135 140 135 142
9 134 141 134 143
10 132 139 132 140
11 131 138 132 138
12 125 135 129 136
13 123 132 126 130
14 120 130 125 131
Experimental Protocol:
The rats were kept in a constant temperature environment while they were provided with free
access to food and water. For 7 consecutive days, the mean arterial pressure of the rats was
measured daily using a non-invasive method (tail cuff). The tail cuff method allowed the
researchers to measure blood pressure in a conscious rat quickly. The new compound Lavblod
was given to the rat in their food from day 8 for another 7 days, while mean arterial pressure
continued to be measured from each rat daily.
Experimental Data:
The data table is available on LMS as an Excel Download.
Question 5 (20 marks)
Using GraphPad Prism, present Carly’s data graphically and analyse her data statistically.
In your answer you should:
! Include the Graph plotted from GraphPad Prism (export as a JPG image and insert into your
submission)
A. Explain why you have chosen to present her data in the way that you have chosen
B. State the type of data analysis that you have included (consider what type of statistical
analysis is appropriate for this type of data)
! Justify your choice with a detailed explanation of the rationale for the statistical
analysis chosen
C. Report the P-value from the statistical analysis you have conducted using GraphPad Prism.
D. From your statistical analysis, what is your conclusion from Carly’s preliminary data about
the efficacy of her drug Lavblod?
In your answer, you should explain any manipulation (if any) you have done to the data to
produce your graphs and statistics. If you have grouped data together, you should identify
what data were grouped and how.
In this question ~10 marks is allocated to the graphical presentation of the data including
the rationale, ~10 marks is allocated to the statistical analysis and the relevant explanation.
Note: You will need to think about the organisation of the data and how you copy and paste
this data into GraphPad Prism.
First, consider the type of data that is collected and what is the most appropriate type of graph
and statistics to present and analyse this data, respectively. Consider the message or
information that Carly may be trying to communicate with her data. What is she trying to
show? Will your selected graph show that information?
Second, make sure you use the Appendix 3 in the lab manual to help you navigate GraphPad
Prism.