Tag Archives: sympathetic nervous system

Beats & Breathing
Thomas Asama
Senior
Human physiology major
University of Iowa

My Research Project

Healthy amounts of oxygen are necessary for almost every tissue in the body. Refined mechanisms function to keep oxygen levels within healthy and functioning ranges. A key player in this oxygen regulation, known as the peripheral chemoreflex, acts to sense oxygen in the blood by way of the carotid bodies. Carotid bodies are small structures located next to the carotid arteries in the neck. When the carotid bodies sense that oxygen levels have fallen below normal values, the body responds by activating the sympathetic nervous system (SNS).

The SNS responds to many different bodily stressors and works to increase oxygen uptake to restore oxygen levels. Diseases, however, can disturb this carefully calibrated system. In obstructive sleep apnea (OSA), for example, the airway becomes blocked periodically during sleep, resulting in episodic cessations of breathing and consequential drops in oxygen levels. These frequent periods of low oxygen can cause two issues: first, increased stimulation of the carotid bodies also increased their sensitivity so that normally nonproblematic decreases in oxygen can trigger their activity; second, increased frequency of low oxygen periods and increased sensitivity of the carotid bodies result in an overactive SNS.

The SNS is one of the body’s general response pathways and works to increase oxygen levels while simultaneously increasing blood pressure. Overactivity of the SNS can lead to chronic high blood pressure which places individuals at risk of stroke, heart failure and many other health issues. By looking for possible ways to alleviate these issues, some animal research has suggested that the molecule nitric oxide (NO) has the ability to desensitize the carotid bodies. Additionally, significant literature has demonstrated that supplementing nitrate (NO3) serves as a way to increase NO availability in the body. Our study intends to assess if supplementation of nitrate in the form of beetroot juice has the ability to decrease the sensitivity and over-responsiveness to low oxygen levels in patients with OSA. Beetroot juice is a relatively cheap and readily available supplement and provides an easily accessible treatment for the general population. If a strong correlation is found, this study will open the field to further research projects pursuing beetroot juice supplementation as adjunct therapy to decrease high blood pressure in the OSA population.

Realities of Research

Research is the epitome of the ability to be dynamic; no complication or problem has one solution. A general image of research provides an image of a lab coat-clad scientist in a sterile silver lab with seemingly perfect and exact run experiments. However, while strongly ordered and rational, the research was often far more less sterile than I had originally planned. Because I was working with human research, a large part of my time in the lab was dependent on recruiting subjects. We had various study days throughout the summer working on collecting data for analysis. I quickly realized there wasn’t one way to view or process our results. I spent many hours spent organizing and reorganizing data in excel, trying to find the best way to compare the different data sets we had been collecting. As the summer went on, I found cleaner and clearer ways to assess and group the data we collected. Ultimately, a large portion of research functions as a product of experience. This summer’s fellowship provided significant time where I could devote myself specifically to this end.

Life as a Scientist

Some children say they want to be an astronaut or a ballerina, and then the nerdier contingent always goes for scientist. Yet, it is seldom true that we know what that kind of life entails. I was amazed by the endless room for growth. On a broader level, there was a vast range of autonomy working and planning as a scientist. What were the next steps? How did today’s data play into the future’s experiments? Each possibility demanded a pursuit of deeper knowledge and expertise in the field. I had the opportunity to attend several research presentations throughout the summer and was constantly amazed by the level at which the professors and researchers considered and analyzed the presentations.

While the opportunity to learn was constant, I was not a fan of the variability of pace in the lab. A big part of this is unique to human research, but the recruitment process meant that some weeks we had no studies and others we had seven or eight. This made it difficult to routinize my work, as each week was different from the last. Nonetheless, during my time in the lab, I had significant opportunities to discuss the content and implications of our research with others. Having this opportunity to discuss physiology solidified my understanding and clarified my misunderstandings of many topics. Likewise, working as a team, each member made up for and filled the needs of others on the team. In this way, together we strove for excellence and efficiency throughout the summer. 

References:

Beets, Border, Diet [Online]. Prexels. https://www.pexels.com/photo/beets-border-diet-food-533298/ [16 Jul. 2019].

Thomas Asama is in his final year of pursuing a bachelor of science in human physiology at the University of Iowa in Iowa City. His undergraduate research experience has been under the mentorship of Dr. Darren Casey, Human Integrative Cardiovascular Physiology Laboratory in the department of physical therapy and rehabilitation science at the University of Iowa. Thomas received funding for his summer research as an Undergraduate Summer Research Felllow (UGSRF) from the American Physiological Society. After completing his undergraduate studies, Thomas plans to attend graduate school for a doctorate in physical therapy, with hopes of pursuing a career in clinical physical therapy.

Learning to Become a Researcher

When people or animals feel threatened, their sympathetic nervous system, a.k.a. ‘fight-or-flight’ system, releases chemicals that increase their blood pressure and heart rate to prepare for fighting or fleeing danger.  Unfortunately, when someone is obese or eats a chronically high-fat diet, their fight-or-flight system can be in an almost permanent state of overdrive.  This can place too much strain on the heart and blood vessels, potentially leading to hypertension (high blood pressure) and subsequent cardiovascular disease such as a heart attack or stroke.  My research project for the summer was to identify specific pathways in the mouse brain that influence the fight-or-flight response.  More specifically, I aimed to determine how inhibition of the dorsomedial hypothalamus (an area of the brain) by neuropeptide-Y (a brain-specific chemical messenger) leads to decreased activity in the fight-or-flight system.  By determining how various chemicals and pathways in the body and brain influence the fight-or-flight system, we may be able to find new treatments for people who have hypertension, hopefully increasing their longevity by decreasing their risk for serious conditions like heart attack or stroke.

 

Working in a research lab is simply amazing.  There is an almost endless amount of techniques, equipment, and software available to learn how to use.  This summer I have learned how to perform immunohistochemistry, how to use a confocal microscope, and how to utilize different analysis software programs to interpret results from fluorescent images.  If time permits, I may even learn how to perform microinjection surgery on a mouse and how to use RNAscope to complement my immunohistochemistry experiments.

 

Two things that surprised me about working in a research lab were how time-consuming experiments can be, and how expensive research supplies are.  For instance, it takes a minimum of sixteen days post-injection before the mouse brains are ready for me to begin processing them.  The brains must then be frozen, sectioned, immunohistochemically treated, mounted onto slides, then imaged, all of which adds up to around thirty hours of processing for a set of three or four brains.  Additionally, much of the processing utilizes expensive solutions and equipment, such as the $400 primary antibody used in the immunohistochemistry, or the fluorescent microscope which costs around $55/day to use for imaging.  This experience helped me to realize the importance of organization, precision, and time-management when conducting an experiment, since any mistake could result in hundreds of dollars wasted and countless hours lost.  Thankfully the experiments I’ve conducted so far this summer have turned out great, and I look forward to starting my next large batch of experiments next week.

 

The day-to-day life of a scientist is highly variable based on my experience this summer.  During any one week I might complete a variety of different tasks based on the needs of my research project as well as the needs of my lab colleagues. While there are general deadlines to be met for certain things and some experiments that require assistance from others, for the most part I am free to schedule which tasks I will be working on for any given day.  One downside to working in research is that since certain equipment is too expensive for each lab to have one of their own, it must be purchased and shared by the whole department.  For instance, the fluorescent microscope that I use is a very popular tool for the type of research done in our department, so you must make a reservation in order to use it.  Unfortunately, if your imaging is taking longer than expected and you didn’t reserve enough time on the microscope to finish, you could end up waiting an entire week before another reservation is available.  Thankfully, with careful planning, this problem can usually be avoided.

 

Overall, working in research as part of a team with the members of my lab has been wonderful.  Each person has their own unique background in research, and since I’m the most junior member of the lab there is a wealth of knowledge I can learn from each of them.  I truly appreciate how much each of my lab colleagues is willing to teach me what they know, provide answers to my questions, and give me guidance for not only my research project, but for my education and career goals as well.

 

Alyssa Bonillas is a senior at Portland State University in Portland, OR, majoring in both Biology and Psychology.  She is a Hearst Fellow working in Dr. Virginia Brooks’ lab at the Oregon Health & Science University in Portland, OR.  Alyssa’s fellowship is funded by APS through a grant from the Hearst Foundation.  After graduation, Alyssa plans to further her education by completing an MD/PhD program, and continuing on to become a physician-scientist at an academic research institution.