Sodium-Potassium Pump

When you complete a workout, you feel good right? You see veins you didn’t know you had, you’re sweating and you have the infamous muscle “pump. No more of that mush that you felt before you began your workout. It’s great! But have you ever wondered what causes that reaction? What actually gives you that “pump” or makes you look “swole”? You can thank your trainer and amazing ability of sticking to your phenomenal chicken diet. And mom of course. But you know what you’ve forgotten?? To thank SCIENCE! In particularly, the Sodium Potassium Pump! Why you ask? It’s like a distant, twice removed through marriage, cousin who you never see and talk to. But little did you know, that pump is one of the primary reasons for that muscular reaction to all your hard work. Let’s start from the beginning.

      First, we need to completely debunk the myth that salt in your diet is the root of all evil. It’s not. It actually assists more than it hinders, given the proportionally correct amount is ingested based on what the body needs. According to the University of Maryland Medical Center, sodium (Na+) is an element the body needs to work properly by using the positively charged ion to “control blood pressure and blood volume”. This helps to regulate nerve and muscle functions, ensuring they work properly. Too much sodium and too little sodium can both cause the body its fair share of problems and the average adult should intake approximately 2,300 mg of sodium per day. This does not account for active lifestyles. Sodium that leaves the body will need to be replaced, so this amount is subject to vary from person to person.

       Next we need to understand that no one goes anywhere without a friend. In this case, sodium’s friend will be potassium. This is sodium’s partner in crime and is the other reason for the Sodium Potassium Pump. According to the University of Maryland Medical Center, potassium (K+) is “crucial to heart function and plays a key role in skeletal and smooth muscle contraction”. It is also a positively charged ion that regulates property cell, tissue and organ function within the body. Just like sodium, potassium also has a recommended daily value for adults which is approximately 4,700 mg per day and there is such a thing as too much or too little potassium.

      Now for the exciting stuff and what you’ve all been waiting for….the Sodium Potassium Pump. You may be thinking to yourself, “Christie, what does this even have to do with working out?” I’ll tell you! This pump is a protein that helps to regulate and distribute sodium and potassium appropriately across a cell membrane. According to RCSB Protein Data Bank, the pump is “found in our cellular membranes, where it is in charge of generating a gradient of ions”. This is the mother of the cell that separates the kids. You see, in order for a cell to function properly, it needs equilibrium. In this case, the muscular cell functions at its prime with a balanced ratio of potassium inside the cell (cytoplasm) to a ratio of sodium outside of the cell (extracellular fluid). According to the US National Library of Medicine National Institutes of Health, this ratio is a 3:2. The pump will take 3 sodium ions from inside the cell and expel them into the extracellular space, basically kicking them out. Then, it will grab 2 potassium ions and bring them into the cell. It constantly works to maintain that balance. This is the magic ratio, the ultimate guide to cell zen.

     You may be wondering what happens when all the ions are transferred and in their appropriate homes. Then what? Why do we even need this pump anymore? Because little did we know, sodium and potassium are sneaky little bastards. Again, Davidson Colleges comes to the rescue and explains that though active transport, sodium and potassium ions are transported across the cell membrane against their concentration gradients. It’s like telling a child they can’t play on a certain yard. What do they do? They cross the semi permeable fence and into the yard they were banned from playing in. This is where the pump is continuously using its efforts and energy to put everyone back in their place. It’s a never ending cycle of taking the children out of the neighbors yard and putting them back in their own.

     So what? Why is this so important that we maintain this ratio and that the pump functions how it’s suppose to? I’m glad you asked! Aarhus University explained it perfectly when they said the pump “is very important in our lives because it acts as a generator that provides the cells with electricity and thus entirely controls both our movement apparatus and our thought apparatus.” Since both sodium and potassium are positively charged ions, they create and electrical current within our muscle fibers. WHAT?! No one said anything about electricity! Oh yes. Electricity. This is how the pump functions. This is what makes it go back and forth like a enclosed seesaw, taking in and spitting out ions. By using a high energy molecule called Adenosine Triphosphatase (ATP), the pump does just that. Almost like a magnetic pull, sodium is pulled from inside the cell and takes a seat in the pump. Once the pump is filled to maximum capacity with 3 sodium ions, an ATP molecule attaches a phosphate molecule onto the enzyme. As the US National Library of Medicine National Institutes of Health says when this molecular transfer occurs, “voltage jumps elicit brief charge movements, consistent with displacement of ions along the ion pathway while one gat is open but the other is closed.” This basically means it an electric shock causes the pump to close and sodium enjoys a ride while the pump changes shape and opens up in the opposite direction. Once opened toward the extracellular fluid of the cell, sodium is booted off the ride and makes room for 2 potassium ions. When they are comfortable and in their seats, the phosphate molecule dislodges from the pump. This in turn, causes it to close once again and open toward the cytoplasm of the cell. There it remains until the process is repeated over and over again. It’s like a biased ride that only allows one type of ion on the ride at a time.

       I know, this information is just thrilling. Riveting actually. But wait, there’s more! Now that you have a better understanding of how the Sodium Potassium pump works, what does this mean to you and why is it important? This is where those ratios really start to matter. If there are an excess or deficit of one or both ions, there are consequences. These vary from migraines to muscle spasms to paralysis of the pump. The human body doesn’t like to be anything else except for perfect. So what does it do? It makes up for the inconsistencies by adding water to whatever side is lacking ions. When the deficit is inside the cell, Nobel Prize winner Jens C. Skou tells us, “since the membrane is permeable to water, water will flow in, and as the lipid bilayer cannot resist a hydrostatic pressure the cell will swell and finally burst.” This destruction of the cell will thus render some of the above side effects.

     However, when the body is taking in the proper amounts of potassium and sodium, this is where the beneficial side effects occur. The combination of the water and sodium in the extracellular fluid produce what we all know and love as the “pump”. This is done through the combination of the fluid and the cell volume pairing like peanut butter and jelly. This, ladies and gentlemen, is when perfect harmony is present. When sodium and potassium work in unison with the pump, not to mention the help of proper hydration, and produce the holy “pump”.

     

http://www.nobelprize.org/nobel_prizes/chemistry/laureates/1997/skou-lecture.pdf