The sodium-potassium balance (Pt. 1)
The health of the cell is of utmost importance for the heart. A balance of electrical minerals (electrolytes) both inside and outside the cell provides a flow of energy that allows the heart to beat with the proper rhythm (1). Due to the constant pumping action of the heart, a steady and constant flow of this electrical energy is key for proper heart function. This is made possible by the presence of pumps on the cell membrane that turn each of our cells into a small battery, capable of releasing and storing energy and maintaining an electrical charge.
We saw how an alkaline diet, together with a good nutritional protocol, like the ‘Heart and Body Extract’, are the best sources of these electrolytes, namely, sodium, potassium, calcium and magnesium. We also saw how potassium has a critical role for heart health as pointed out by the ‘National Council on Potassium in Clinical Practice’. Such research represents a new focus in the field of cardiology, and one that is receiving much interest from many health care professionals. One of these health care professionals is Richard D. Moore, M.D., Ph. D., who in his book ‘The salt solution’ (2), goes into deep detail about the importance of balancing sodium and potassium for heart health. He has worked with other doctors and published his research on how the sodium potassium pump influences insulin in the body.
In today’s blog, we will focus on his work. Specifically, we will look at how the sodium-potassium pump works to keep our heart healthy, and how it is needed to keep other important pumps working in the cell, the ‘sodium-acid exchange acid pump’, and the ‘sodium-calcium exchange calcium pump’.
Basics of cell biology
90% of the potassium in the body is found within cells.This compartmentalization depends on its active transport through the cell membrane by the sodium-potassium pump. Before we look deep into this mechanism, we need to understand something basic in cell biology: all cells consist of a surface membrane called ‘plasma membrane’. Across this plasma membrane there is a voltage difference, with the inside of the cell being negative with respect to the outside. This voltage difference is made possible by the presence of the sodium-potassium pump, which acts as a microscopic electric generator of current carried by positive sodium ions.
The main job of this pump is to move sodium out of the cell and move potassium in. The purpose of this distribution is to generate a voltage between the inside and the outside of the cell: With each cycle, the sodium-potassium pump moves more sodium ions out than potassium ions in. The sodium pumped out is positively charged while the inside of the cell is negatively charged.This movement of electric current out of the cell leaves the inside more negative. In this manner, the sodium-potassium pump generates an electrical current, creating a powerful electric field across the cell membrane. The negative charge, and the lower concentration of sodium inside the cell, create a very strong ‘tug’ which makes sodium ‘want’ to leak back into the cell. This acts like a ‘sodium battery’ that is capable of performing work in a manner similar to a car battery.
The energy this battery creates is so crucial, that life could not be possible without it. This is proven by the astonishing number of pumps the body has: each of our 100 trillion cells have between 800,000 and 30 million of these pumps on the cell membrane (4). This great amount of electricity the human body is capable of generating also means that just a slight slowing down of these pumps can mean a tremendous decline in overall health.
It was originally thought that only nerve, muscle and kidney cells made use of the sodium-potassium pump. The reason for this might have been the fact that nerve and muscle cells have the largest potential (70 and 90 Volts respectively). However, it is now known that all cells in the body use the sodium-potassium pump. A nerve impulse, for example, consists of a 1 millisecond switching of the membrane potential from a negative value to a positive value and then back to the negative. This is accomplished by sodium ions rushing into the cell: as sodium rushes into the cell, the positive charge it carries makes the inside more positive. As the inside becomes positive potassium rushes outside the cell. All this process provides the signal for muscles and nerves to contract. When this happens several times, it is the equivalent of ‘running down’ of a battery, which is thought to be responsible for the fatigue we experience when we exercise. The sodium-potassium pump has the key job of restoring the cell’s energy by pushing the extra sodium back out and pulling the missing potassium back into the cell.
The obligatory link between sodium and potassium
Too much focus has been put on just limiting sodium for improving heart health, however, the sodium-potassium pump proves that it is not possible to isolate either sodium or potassium. It is the right ratio of the two that brings cells back into a healthy balance. This is because in the body sodium and potassium oppose one another, when one goes up the other goes down. Increasing potassium causes sodium to be excreted through the kidneys and vice versa. According to Dr. Moore, it makes no sense to talk about one without mentioning the other. He explains that there is a reciprocal relation between the levels of sodium and potassium inside the cell: anything that decreases sodium will increase potassium and vice versa, because the sodium-potassium pump moves sodium and potassium in different directions. In practical terms, without enough potassium, excess sodium cannot be lowered within the cells, in other words, to lower sodium in the cell, it must be replaced by potassium. This is one of the reasons why low salt diets don’t work for people with high blood pressure.
The teeter-totter rule
Dr. Moore refers to this as the ‘teeter-totter rule’. He explains that in the body it is not possible to affect sodium without affecting potassium. Not getting enough potassium and lowering salt intake cannot possibly restore the normal level of potassium and sodium within the cells. This is because sodium and potassium work together: When potassium goes into the cell, sodium must come out and vice versa, because the pressure inside the cells and the pressure outside must remain constant. An indicator of a healthy sodium-potassium pump is a ratio of around 14 to 1 of potassium to sodium inside the cell, and outside the cell the fluid should contain 30 times more sodium than potassium.
We could therefore say that heart health is not a matter of how much sodium or potassium one gets from the diet, but a matter of balance between the two. However, our present diet contains much more salt than our ancestors used to consume, and this has brought an imbalance to the body. Too much salt, without potassium to balance it out, can damage the heart, blood vessels and even bones. Only the right sodium-potassium ratio can reverse this damage.
More roles of the sodium-potassium pump
As we mentioned earlier, the sodium-potassium pump is present in all the cells of the body. Therefore, it has many different and important functions. So far we have explained that the job the sodium-potassium pump has is to move sodium out of the cell while moving potassium in for cells to be able to conduct electricity. But the sodium-potassium pump could do this without generating electricity, and since the body always works to conserve energy, there must be a very important reason for this. What is the purpose for generating electricity?
First of all, this pump helps maintain order in the body, by keeping sodium on one side of the cell and potassium on another side.
Secondly, the strength of this electric field also influences the structure and function of many proteins in the cell, and these proteins, in turn, play an important role in:
- Transporting substances into and out of the cell
- Transmitting hormonal signals, and
- Carrying out a host of enzymatic reactions
Thirdly, the sodium-potassium pump affects a number of functions which in turn influence:
- Cholesterol levels
- How well the heart pumps
- It influences fat metabolism
- It allows nerves and muscles to conduct electrical signals
- It allows sodium to be reabsorbed into the kidneys
- It provides the power for regulation of levels of acid, calcium, and sugar inside the cell (sugar metabolism)
- It governs cell growth and division, which makes it significant for cancer prevention
- It regulates the response to hormones, including insulin
A minor slowing of the sodium potassium pump can affect all of these aspects of health.
Implications for heart energy
Nowhere in the body is the sodium-potassium pump best exemplified than in the heart. Not only because of the number of sodium-potassium pumps heart cells contain, but because the heart is a pump. A pump can be defined as a device that uses energy to move something in a direction opposite to the direction the substance would naturally move if left alone. For any pump to work, energy is required. Both the sodium-potassium pump and the heart use ATP as a source of energy (for more information on ATP please refer to previous blogs). This is the equivalent of a quarter of the energy our body obtains from the food we eat. In this manner, the heart uses energy to move blood against the potential energy force of blood pressure. In the case of the sodium-potassium pump, it also takes energy to move sodium out of the cell, generating an electric current also requires energy. A malfunction of the sodium-potassium pump can mean high blood pressure, stroke, but also osteoporosis, peptic ulcer, stomach cancer, and asthma.