Artic Ground Squirrels

1. Describe I/R injury in your own words
I/R injury is when tissue is damaged due to lack of oxygen.

2. Describe mammalian hibernation, making sure to include specifics on body temperature drops, metabolic rates, and respiratory rates.
Mammalian hibernation is a process the body undergoes when trying to protect against extreme weathers and to help conserve energy for a few weeks or an extended period of time while a food source is scarce. Hibernation is a state where metabolic rate is low or inactive, low heart rate and, slowed breath. Those animals that have small body weights drop drastically in body temps while larger mammals have a smaller change and do not drop as low as an artic ground squirrel can. In artic ground squirrels the
body temperature can drop from 37 degrees Celsius to -3 degrees Celsius.

3. Why are researchers interested in studying mammalian hibernation?
When a mammal enters torpor their bodies experience similar things as one can see with I/R injury, where oxygen levels are decreased significantly but then increased back to normal.

4. In your own words, what is the purpose of this study (hypothesis)?
The purpose of the study is to observe the affects of putting artic ground squirrels and rats into a state of I/R injury. They think that because the artic ground squirrel hibernates, which as stated earlier is a similar thing to I/R injury the myocardial injury will not be as severe as seen on the rats that do not partake in hibernation.

5a. What animal models were used in this study (list all), and which was the experimental and which was the control group?
The animal that were used in this study include, the experimental group, artic ground squirrel excluding juvenile and old squirrels and the control group, adult male Brown Norway and Dahl/Salt Sensitive rats.

5b. Why did the researchers not choose an amphibian (like Xenopus for example) to use for these experiments?
The rats where used for this experiment because they are orthologous to the artic ground squirrel, sections in their genome matched up for the abundance of myocardial protein.
Although amphibians do hibernate the metabolic process they experience is different than those of the squirrel and rat. The rate they burn off energy is much slower and a frog can become frozen but the vital organs do not freeze completely, they don’t breath nor have a beating heart, when they thaw out thy can still be alive.

6. What was the significance of using two different rat models (the Brown Norway and Dahl/salt-sensitive)?
The two different rat models is useful because Brown Norway is a strain that is more resistant against myocardial I/R while the Dahl/salt sensitive rats are more susceptible to myocardial I/R.
This gives the researches a broader view of animals that do not go through what the artic ground squirrel do.

7a. What is troponin?
Troponin is a globular protein that assists in muscle contraction.

7b. What do levels of troponin in the blood suggest?
If there are high levels of troponin suggest that the heart has been damaged. When the heart is damaged this proteins are released into the blood.

8a. In figure 2A, are the results what you would expect to see comparing the arctic ground squirrel (ASG), the Brown Norway rat (RAT (BN)), and the Dahl rat (RAT (SS))? Discuss the results in your own words!
The results are what I would have expected to see comparing the artic ground squirrel, and Brown Norway rat and Dahl rats. The graph shows that rodent with the least amount of heart damage is the artic ground squirrel that hibernates during the winter and that the Dahl Salt sensitive rat has the most levels of troponin in the blood levels meaning that the Dahl Salt sensitive rate had the highest about of heart damage. The artic squirrel is able to provide the most protection for their
hearts.